H Using chemistry Unit guide - Physicslocker 3/Unit H.pdf · H Using chemistry Unit guide ... a list into two groups: natural and man-made. Brainstorming Pupils work in groups to

H Unit guideUsing chemistry

Sheet 1 of 1© Harcourt Education Ltd 2004 Catalyst 3This worksheet may have been altered from the original on the CD-ROM.

Where this unit fits in Prior learningThis unit builds on:unit 9E Reactions of metals and metal compounds and unit 9F Patterns of reactivity. This unit providesopportunities to revisit and revise topics met in other units in Years 7 and 8. With some pupils, teachersmay wish to concentrate on some of the new topics, extending activities, and with others to spend moretime on revision of previous work.

The concepts in this unit are: chemistry forms the basis of living processes, product manufacture and most forms of energy production.

This unit leads onto:work in key stage 4 on using chemical reactions to make new materials.

This unit relates to:other units, particularly to aspects of photosynthesis and respiration in unit 8B Respiration and unit 9CPlants and photosynthesis, and to units about energy – unit 8I Heating and cooling and unit 9I Energyand electricity.

To make good progress, pupils startingthis unit need to:• have carried out a test for carbon

dioxide• know that burning involves a reaction

with oxygen in which oxides are formed• know that new materials are formed

when chemical reactions occur and canidentify evidence of these

• have used symbols and formulae andword and/or symbol equations

• recognise an order of reactivity ofmetals.

Framework yearly teaching objectives – Particles• Identify evidence which indicates that a chemical reaction has taken place, such as the association of energy transfer with chemical change.• Recognise that chemical reactions can be modelled by assuming that atoms can rearrange themselves, and that this can happen in only a limited

number of ways, for example: A + B → AB, AB + CD → AD + CB.• Use the particle rearrangement model to:– predict the names and formulae for products that might be formed from given reactants;– write word and symbol equations for some simple reactions;– explain why mass is conserved in chemical reactions.

Expectations from the QCA Scheme of Work At the end of this unit …

… most pupils will … … some pupils will not have made so muchprogress and will …

… some pupils will have progressed furtherand will …

in terms of scientific enquiry NC Programme of Study Sc1 2g, i, j, k, l, m

• make measurements of temperature and massadequate for the investigation they arecarrying out

• describe some of the stages in development ofa new product.

• make measurements of temperature and mass• identify some products that have recently

been developed.

• explain the stages of development of a newproduct.

in terms of materials and their properties NC Programme of Study Sc2 5a; Sc3 1e, f, 2a, g, h, i, 3b, h; Sc4 5a

• describe how chemical reactions are used tomake new products and as a source of energy

• use the particle model to explain how mass isconserved during chemical reactions and otherchanges

• represent chemical reactions by wordequations.

• name some products produced by chemicalreactions and identify burning as a reactionwhich produces energy.

• reconcile observations in which mass appearsto be lost with the principle of conservationof mass, and represent some reactions bysymbol equations.

Suggested lesson allocation (see individual lesson planning guides)Direct route

H1Products fromreactions

H2Energy fromreactions

H3Reactions inbalance

H4The story of burning – Thinkabout what happens inburning and how we found out

Booster 4Focus on particles 2 –Chemical changes

Extra lessons (not in Pupil book)

Much extra practice of writing word equations (green) and balancing chemical equations (red). Review and assess progress (distributed appropriately)

MisconceptionsMany pupils think that chemistry is a strange pastime that is only important to people in white coats – in fact almost everything in our lives relies on it.

Additional informationMany more examples could be added of the ways in which chemistry ‘touches the lives’ of the students.

Health and safety (see activity notes to inform risk assessment)Risk assessments are required for any hazardous activity. In this unit pupils use flammable liquids and solutions which may be hazardous. They alsoobserve some reactions between elements, use gas syringes and observe burning magnesium.

G-I-Unit Guides.qxd 16-Jun-04 3:12 PM Page 8

H1Lesson

planning guideProducts from reactions


Learning objectivesi Chemistry forms the basis of living processes, product manufacture and energy production.ii Identify some products that have recently been developed.

Scientific enquiryiii Describe some positive and negative effects of scientific and technical developments. (Framework YTO Sc1 9a)

Learning outcomes

Suggested alternative plenary activities (5–10 minutes)

Review learning

Pupils match chemicalproducts with their uses.

Sharing responses

Card game to useinformation gained fromActivity H1a to match thenames of jobs to theproducts produced.

Group feedback

Pupils report to the classtheir ideas from ActivityH1b. These are summarisedinto a flow chart on theboard.

Word game

Wordsearch using wordsfrom the activities.

Looking ahead

Show video of the burningand use of a range of fuels,e.g. natural gas, wood,coal, petrol, fuel oil. Catalyst InteractivePresentations 3

Suggested alternative main activitiesActivity

Textbook H1

Activity H1a Discussion

Activity H1b Paper

Learningobjectivessee above

i and ii

i

i, ii and iii

Description

Teacher-led explanation and questioning OR Pupils work individually,in pairs or in small groups through the in-text questions and thenonto the end-of-spread questions if time allows.

Scientists’ jobs Pupils look at different jobs that involve chemistry.

Development of aspirin Pupils make a summary of the key stages indevelopment from information provided on a worksheet.

Approx. timing

20 min

20 min

15 min

Target group

C H E S

R/G G R S

✔

✔ (✔)

Key wordsraw materials

Out-of-lesson learningHomework H1Textbook H1 end-of-spread questionsActivity H1b

Most pupils will ...

• understand the importance of chemistry intheir everyday lives

• know some key examples of this.

Some pupils, making less progress will ...

• understand how chemistry effects our lives.

Some pupils, making more progress will ...

• have an understanding of some productmanufacturing processes.

Suggested alternative starter activities (5–10 minutes)

Introduce the unit

Unit map for Usingchemistry.

Share learning objectives

• Describe how most productsare made from chemicalreactions.

• Describe the key stages inthe development of a newproduct.

• Identify some positive andnegative effects of newproducts. (Sc1)

Problem solving

Pupils separate products ina list into two groups:natural and man-made.

Brainstorming

Pupils work in groups tobrainstorm the question‘What everyday productshave been made bychemists?’

Capture interest

Show photos and packagingto demonstrate to pupilsthe vast range of materials obtained fromchemical reactions. Catalyst InteractivePresentations 3


H2Lesson planning

guideEnergy from reactions


Learning objectivesi Appreciate that chemical reactions, including combustion and displacement, can release energy, including voltaic cells. (red only)ii Understand combustion reactions of various fuels.

Scientific enquiryiii Make measurements of temperature.iv Use information from secondary sources to draw conclusions. (Framework YTO Sc1 8d)


Textbook H2

Activity H2aPractical

Activity H2bDiscussion


i and ii

i, ii and iii

i and iv

Description

Teacher-led explanation and questioning OR Pupils work individually, in pairsor in small groups through the in-text questions and then onto the end-of-spread questions if time allows.

Measuring energy change Pupils measure the energy changes for some metaldisplacement reactions.

The right fuel for the job Pupils look at different scenarios in which a fuelis used and decide what fuel is best for the job.

Approx.timing

20 min

30 min

20 min

Target group

C H E S

R/G G R S

✔ ✔

✔

Learning outcomes


• know the basic fuel reactions and be able towrite word equations for them

• have some understanding of the relativeadvantages/disadvantages of different fuels.


• appreciate that chemistry is used to providemuch of our energy.


• be able to write balanced chemical equationsfor the key reactions

• know that electrical energy can be producedfrom a voltaic cell.

Key wordsNone

Out-of-lesson learningHomework H2Textbook H2 end-of-spread questions


Recap last lesson

Pupils match jobs todefinitions/descriptions.


• Describe how chemicalreactions can releaseenergy.

• Make measurements oftemperature. (Sc1)

Problem solving

Pupils work in groups toanswer the question ‘Whatevidence do we have thatsome chemical reactionsrelease heat?’

Capture interest (1)

Demo of lighting a match.


Demo of a voltaic cellshowing voltage and lamp lit.


Review learning

Pupils write a definition ofthe word ‘fuel’. Individualsread out their definitions to the class.

Sharing responses

Pupils report results ofActivity H2a to the class.Results are summarised onthe board and discussed.

Group feedback

Pupils work in groups using information fromActivity H2b to produce anadvertising poster for afuel, designed to appeal tothose who might purchasethe fuel.

Word game

Pupils use cards toconstruct word equationsfor the reactions in Activity H2a.

Looking ahead

Demo adding barium nitratesolution a little at a timeto sodium sulphatesolution, each time gettingmore precipitate. Ask pupils‘Could we go on doing thisforever?’


H3Lesson planning

guideReactions in balance


Learning objectivesi Understand what happens to the particles in a chemical reaction.ii Know that and understand why mass is conserved in a chemical reaction.iii Learn how to balance chemical equations. (red only)

Scientific enquiryiv Make measurements of mass. (Framework YTO Sc1 9d)v Describe patterns in data. (Framework YTO Sc1 9f)


Recap last lesson

Pupils match names of fuelswith descriptions of fuelappearance and/or use.

Share learningobjectives

• Describe what happens toatoms in chemicalreactions.

• Explain that mass isconserved during chemicalreactions.

• Describe patterns in data.(Sc1)

Problem solving

Demo of a precipitationreaction of barium nitratesolution added to sodiumsulphate solution on abalance to show no masschange.

Brainstorming

Pupils work in groups tobrainstorm the question‘How can we show thatmagnesium gains mass as itburns?’ Groups report ideasto the class, leading toActivity H3b.

Capture interest

Demo of a piece ofmagnesium ribbon burning.Ask pupils the question ‘Doyou expect the ash to belighter or heavier than themagnesium metal?’


Textbook H3

Activity H3a Practical

Activity H3b Practical


i, ii and iii

i, iii, iv and v

i and v

Description


What happens to the mass? Pupils learn that the mass of theproducts of a chemical reaction is the same as the mass of thereactants.

Burning magnesium Pupils measure mass of magnesium before andafter burning.

Approx.timing

20 min

25 min

30 min

Target group

C H E S

R/G G R S

✔

✔ ✔


Review learning

Role play of magnesiumburning, with pupils actingas magnesium atoms andoxygen molecules.

Sharing responses

Groups report their resultsfrom Activity H3a to theclass. Discussion leads toideas of conservation ofmass.

Group feedback

Groups report their resultsfrom Activity H3b. A‘perfect’ set of results isused to write a symbolequation. Pupils suggestwhy their results do not fitthe equation exactly.

Word game

Pupils work in groups toplay game of ‘Taboo’ usingwords relevant to theseactivities.

Looking back

Pupils revise andconsolidate knowledge fromthe unit.

Learning outcomes


• understand chemical reactions in terms of therearrangement of particles

• appreciate why this means that the mass isconserved.


• learn that ‘mass stays the same’ in a reaction• have had some reinforcement of the ‘particle

model’.


• be able to balance simple chemical equations.

Key wordsconservation (of mass)

Out-of-lesson learningHomework H3Textbook H3 end-of-spread questions


H4Lesson planning

guideThe story of burning – Thinkabout what happens in burningand how we found out


Learning objectivesi Understand what happens when things burn.ii Follow a logical sequence of ideas.The structure of this lesson is based around the CASE approach. The starter activities give concrete preparation. The main activities move away from theconcrete towards a challenging situation, where pupils need to think. The extended plenary gives pupils time to discuss what they have learnt, tonegotiate a method to commit to paper and express their ideas verbally to the rest of the class.

Scientific enquiryiii Explain how scientific ideas have changed over time. (Framework YTO Sc1 9a)iv Describe how evidence does or does not support a conclusion. (Framework YTO Sc1 9g)


Bridging to the unit

Pupils look at photos showing theuse of oxygen in oxyacetylenewelding and/or cutting.Catalyst Interactive Presentations 3

Setting the context

Pupils work in groups tobrainstorm the question ‘Howdo we know that the aircontains oxygen?’

Concrete preparation (1)

Demo of burning a candle floating on a Petri dish in a trough of water underan upside-down beaker to show thatsome of the air is used up.


Measure mass of candle before andafter burning. Ask pupils where themass has gone.


Textbook H4

Activity H4a Practical

Activity H4b ICT


i, ii and iii

i and iv

i and iii

Description


Combustion of a candle Pupils are shown that the combustion of acandle produces carbon dioxide and water.

The discovery of oxygen Pupils search the Internet for informationabout early theories of combustion and the work of Priestley andLavoisier.

Approx.timing

30 min

15 min

20 min

Target group

C H E S

R/G G R S

✔ (✔)

✔


Group feedback

Groups report their results from Activity H4a to the class for discussion.They then compare what they have learned from practical evidence withthe ideas of Priestley and Lavoisier. They see that evidence helps toconfirm or change people’s ideas.

Bridging to other topics

Show video or photos of space rockets taking off. Explain that the fuel isthe gas hydrogen, and ask them to suggest how it is stored in the rocketand where the oxygen for burning comes from. Catalyst Interactive Presentations 3

Learning outcomes


• be able to follow the development of ourideas about burning

• appreciate why some combustion reactionsappear to show mass loss whilst others showa mass gain

• have some understanding of the importance ofscientific hypotheses and the predictions thatare made from these in the development ofour scientific ideas.


• appreciate that scientific ideas have changedwith time – we did not always know what weknow now.


• gain greater insight into the workings ofscience: its strengths and limitations; the wayit has developed over time and hopefully theinference that it will continue to develop.

Key wordsNone

Out-of-lesson learningTextbook H4 end-of-spread questions


H Unit mapUsing chemistry


Copy the unit map and use these words to help you complete it.You may add words of your own too.

alcoholatomsbalanced equation Rcarbon dioxidecarbon monoxide Rcoalcombustioncrude oildigestionethanolfermentation

foodfossil fuelsfuelsglasshydrocarbonshydrogenironmetalsmethanenatural gaspetrol

phlogistonphotosynthesisplasticspollutionproductsraw materialsreactantsrespirationrubbersteelwater

Chemicalreactions

Useful productsfrom reactions

The discovery of oxygen

Conservation of massEnergy from reactions

Unitmaps.qxd 18-Jun-04 11:36 AM Page 8


H1 StartersProducts from reactions

Introduce the unit� Either draw the outline of the unit map on the board then ask pupils to give

you words to add, saying where to add them. Suggest some words yourselfwhen necessary to keep pupils on the right track.

� Or give out the unit map and ask pupils to work in groups deciding how to addthe listed words to the diagram. Then go through it on the board as each group gives suggestions.

Share learning objectives� Ask pupils to write a list of FAQs they would put on a website telling people

about everyday chemistry. Collect suggestions as a whole-class activity, steeringpupils towards those related to the objectives. Conclude by highlighting thequestions you want them to be able to answer at the end of the lesson.

Problem solving� Pupils work in groups to separate a list of chemical substances under two new

headings: ‘Natural substances’ and ‘Man-made substances’.� Each group in turn reports some of the items in each of their lists to the class.

Write up correct lists on the board as each group has their turn.� Discuss and explain the correct classification for any substances placed in the

wrong list.� Some items are not easy to classify, and may lead to quite active class discussion.

Brainstorming� Pupils work in groups to brainstorm the question ‘Which everyday products

have been made by chemists?’� Each group chooses three products from their ideas.� Each group in turn reports their three products to the class for discussion. Make

a list of the products on the board.� For any products incorrectly attributed to chemists, explain why they are

incorrect. Because the definition is ‘made by chemists’, a chemical reactionmust be involved for the material to be classified in this way. Products made bypurely mechanical or physical process are not ‘made by chemists’.

Capture interest� Show pupils photographs and packaging of products produced by chemical

reactions.� Discuss the use of each product.� Relate how raw materials are obtained and then made into useful products by

chemical reactions.� Give a brief but more detailed description of the raw materials used to make

some of the example products from the photographs or packaging.� Emphasise the wide range of useful materials that are produced by chemical

reactions.

➔ Unit map

➔ Pupil sheet

➔ Teacher sheet

➔ Catalyst InteractivePresentations 3


Introduce the unit

Complete unit map forUsing chemistry.


• Describe how most products aremade from chemical reactions.

• Describe the key stages in thedevelopment of a new product.

• Identify some positive andnegative effects of newproducts. (Sc1)

Problem solving

Pupils separateproducts in a list intotwo groups: naturaland man-made.

Brainstorming

Pupils work in groups tobrainstorm the question‘Which everyday productshave been made bychemists?’

Capture interest

Show photos andpackaging to demonstrateto pupils the vast range ofmaterials obtained fromchemical reactions. Catalyst InteractivePresentations 3

H-Starters.qxd 08-Jun-04 1:18 PM Page 1


Problem solving

Here is a list of chemical substances. Divide up this list to maketwo new lists under the headings ‘Natural substances’ and ‘Man-made substances’.

air copper petrol

alcohol crude oil polystyrene

aluminium glass rubber

bread gold water

cabbage hydrogen wood

coal iron


Sheet 1 of 1

StartersH1 Products from reactions

Problem solving

Here is a list of chemical substances. Divide up this list to maketwo new lists under the headings ‘Natural substances’ and ‘Man-made substances’.

air copper petrol

alcohol crude oil polystyrene

aluminium glass rubber

bread gold water

cabbage hydrogen wood

coal iron

© Harcourt Education Ltd 2004 Catalyst 3This worksheet may have been altered from the original on the CD-ROM.



Problem solvingTeacher sheet

Natural substances

air

cabbage

coal

crude oil

gold

water

wood

Man-made substances

alcohol

aluminium

bread

copper

glass

hydrogen

iron

petrol

polystyrene

rubber

� There may be some confusion amongst pupils as to whether metals such asaluminium and iron should be placed in the man-made list. Because they donot occur naturally as metals, and therefore have to be made from their oresby chemical reactions, this is the correct list. The position of gold and copperare more problematic. Gold does occur naturally as the metal, and isextracted largely by mechanical processes. Copper can be found naturally,but this is rare. Almost all copper is made by chemical reaction from an ore.

� There may also be some discussion about which list petrol should be placedin. It occurs naturally as part of crude oil, but not on its own. It is extractedby fractional distillation, a process that does not involve a chemical reaction.It is not found naturally on its own.

� Many pupils may think that hydrogen is present in the air. Hydrogen ismanufactured by chemical reactions, e.g. cracking of ethane, electrolysis.




H2 StartersEnergy from reactions

Recap last lesson� Pupils work individually or in groups to match jobs to definitions.

� Pupils in turn report their word to definition matches to the class fordiscussion. Write words with agreed definitions on the board.

Share learning objectives� Ask pupils to write a list of FAQs they would put on a website telling

people about the release of energy from chemical reactions. Collectsuggestions as a whole-class activity, steering pupils towards thoserelated to the objectives. Conclude by highlighting the questions youwant them to be able to answer at the end of the lesson.

Problem solving� Pupils work in groups to answer the question ‘What evidence do we

have that some chemical reactions release heat?’

� Each group makes a list of their evidence.

� Groups in turn report their ideas to the class for discussion. Write a listof evidence on the board.

Capture interest (1)� Pupils watch a demonstration of a match being struck.

� After a few seconds of burning, blow out the match and show pupilswhat it now looks like.

� Ask pupils to write down what evidence they have seen that thereaction taking place when the match was struck released energy.

� Choose individual pupils to read out their ideas to the rest of the class.

� Write a list of ‘evidence’ on the board.

Capture interest (2)� Pupils watch a demonstration of a voltaic cell.

� They look for evidence that the reaction is releasing energy.

➔ Pupil sheet

➔ Teacher sheet


Recap last lesson

Pupils match jobs todefinitions/descriptions.


• Describe how chemical reactionscan release energy.

• Make measurements oftemperature. (Sc1)

Problem solving

Pupils work in groups toanswer the question ‘Whatevidence do we have thatsome chemical reactionsrelease heat?’


Demo of lighting a match.


Demo of a voltaic cellshowing voltage andlamp lit.


H2 StartersEnergy from reactions

Recap last lessonTwo lists are given below, one showing four job titles and another showing definitions ofthese jobs.

Match each job title with the correct definition.

You may be asked to explain to the rest of the class why you think a particular definitionmatches the job you have chosen.

Jobs

Machine operator Materials scientistPharmacist Chemical engineer

Definitions

A person who dispenses drugs that have been prescribed by a doctor.A person who designs and runs the manufacturing processes that make substances by chemical reactions.A person who chooses materials with the right properties for a particular product.A person who uses a machine to make a product from one or more materials.


Sheet 1 of 1

StartersH2 Energy from reactions

Recap last lessonTwo lists are given below, one showing four job titles and another showing definitions ofthese jobs.

Match each job title with the correct definition.

You may be asked to explain to the rest of the class why you think a particular definitionmatches the job you have chosen.

Jobs

Machine operator Materials scientistPharmacist Chemical engineer

Definitions

A person who dispenses drugs that have been prescribed by a doctor.A person who designs and runs the manufacturing processes that make substances by chemical reactions.A person who chooses materials with the right properties for a particular product.A person who uses a machine to make a product from one or more materials.



H2


StartersEnergy from reactions

Capture interest (2)Teacher sheetEquipment

� ammeter� 400 cm3 beaker� copper rod� lamp� porous pot� rheostat� switch� voltmeter� zinc rod� copper sulphate solution

Set up the voltaic cell shown in the diagram.

Show pupils the construction of the cell, pointing out the zinc and copper rods,and the copper sulphate solution.

Connect the switch. Point out that the lamp has lit, and that the ammeter andvoltmeter show readings.

Tell pupils that a chemical reaction is taking place, in which the more reactivezinc metal is displacing the less reactive copper from the solution.

Ask pupils what evidence they can see that this reaction releases energy.

ammeter rheostat

voltmeter

switch

voltaic cell

Cu2+ (aq)

Zn2+ (aq)

porous pot

Cu(s)Zn(s)

A

V



H3 StartersReactions in balance

Recap last lesson� Pupils work in groups to match names of fuels with their appearance

and/or use.

� Ask groups in turn to report their matches to the class.

� Discuss and explain any errors. Write the agreed matches on the board.

Share learning objectives� Ask pupils to write a list of FAQs they would put on a website telling people

about what happens to atoms and mass during chemical reactions. Collectsuggestions as a whole-class activity, steering pupils towards those related to the objectives. Conclude by highlighting the questions you want them to beable to answer at the end of the lesson.

Problem solving� Pupils watch a demonstration of the addition of barium nitrate solution to

sodium sulphate solution, with apparatus standing on a top pan balance.

� Ask pupils to note whether the mass changes as the precipitate of bariumsulphate is formed.

� Explain that the total amount of each element present is the same, althoughthe barium and sulphate are now in a solid instead of in solution.

Brainstorming� Pupils work in groups to brainstorm the question ‘How can we show that

magnesium gains mass as it burns?’

� Ask each group in turn to report their ideas to the class for discussion.

� Steer discussion towards ideas of measuring the mass of a piece ofmagnesium before and after burning.

� Ask pupils to suggest what apparatus to use. This leads into Activity H3b.

Capture interest� Demonstrate to pupils the burning of a piece of magnesium.

� Show pupils a piece of unburned magnesium and the ash left after a piece ofmagnesium has burned.

� Ask pupils the question ‘Do you expect the ash to be lighter or heavier thanthe magnesium metal?’

� Expect that most pupils will think that the ash is lighter, but some shouldthink it is heavier. Ask these pupils to explain why.

� If no pupils think the ash is heavier than the magnesium, then suggest this.

➔ Pupil sheet

➔ Teacher sheet

➔ Teacher sheet


Recap last lesson

Pupils match names offuels with descriptionsof fuel appearanceand/or use.


• Describe what happens toatoms in chemical reactions.

• Explain that mass isconserved during chemicalreactions.

• Describe patterns in data.(Sc1)

Problem solving

Demo of a precipitationreaction of barium nitratesolution added to sodiumsulphate solution on abalance to show no masschange.

Brainstorming

Pupils work in groups tobrainstorm the question ‘How can we show thatmagnesium gains mass as itburns?’ Groups report ideas to the class, leading toActivity H3b.

Capture interest

Demo of a piece ofmagnesium ribbon burning.Ask pupils the question ‘Do you expect the ash to be lighter or heavier than the magnesium metal?’



Recap last lesson

For each of the fuels given in the first list, choose the bestdescription of it from the second list.

Fuels

alcohol

coal

crude oil

fossil fuels

hydrogen

natural gas

petrol

propane

wood

Descriptions

A gas obtained from crude oil and used by some people who arenot connected to mains gas.

A black solid consisting largely of carbon.

A liquid used to power motor vehicles.

Fuels that have been formed over millions of years from plants oranimals.

A liquid produced by fermentation and used in some countries asan alternative or additive to petrol.

A solid, renewable fuel.

A gas that burns to form no pollution.

A mixture of hydrocarbons that is separated to provide severaldifferent fuels.

A fuel that is mostly the gas methane.




Problem solvingTeacher sheetEquipment

� 1 mol/dm3 barium nitrate solution

� 1 mol/dm3 sodium sulphate solution

� 2 × 100 cm3 beakers

� top pan balance

1 Pour about 40 cm3 of barium nitrate solution into one 100 cm3 beaker andapproximately the same volume of sodium sulphate solution into a secondbeaker.

2 Place both beakers onto a top pan balance. Ask pupils to note the total mass.

3 Pour the barium nitrate solution into the sodium sulphate solution.

4 Ask pupils to again note the total mass.

5 Remind pupils of the chemical reaction that has taken place.

barium nitrate + sodium sulphate → barium sulphate + sodium nitrate

6 Ask pupils to explain why the mass has not changed.




Capture interestTeacher sheetEquipment

� magnesium ribbon� tongs� Bunsen burner� heatproof mat� watch glass

This experiment should be carried out with the nearest pupil about 2 metres away.The teacher should wear eye protection.

1 Warn pupils that burning magnesium gives out an intensely bright light.Advise that they should look to one side rather than directly at the burningmagnesium.

2 Show pupils the appearance of magnesium ribbon.

3 Grip a piece of magnesium ribbon approx. 10 cm long in a pair of tongs andput it into a hot Bunsen flame.

4 When the magnesium ignites, move the burning metal slightly to one sideof the Bunsen flame.

5 When burning is complete, place the ash onto a watch glass.

6 Show pupils an unburned piece of magnesium ribbon and the ash, for themto make a comparison.




H4 StartersThe story of burning – Think about

Bridging to the unit� Show pupils photographs of an oxyacetylene torch being used for welding or

cutting. Ask pupils to suggest what is in the two gas cylinders being used to supplythe torch. Lead pupils to the idea that one must be a fuel and the other oxygen.

� Ask pupils to suggest why oxygen is mixed with the fuel before it is burned, ratherthan burning simply using oxygen from the air.

� Explain how mixing oxygen with acetylene before burning helps to give a moreefficient burning and so produce a very hot flame.

Setting the context� Ask pupils to work in groups to brainstorm the question ‘How do we know that the

air contains oxygen?’ They should suggest evidence.

� Ask each group in turn to report their ideas to the rest of the class.

Concrete preparation (1)� Demonstrate a burning candle floating on water covered by a beaker.

� Ask pupils why the candle goes out. Elicit the answer that all of the oxygen is used up.

� Ask pupils why the level of water rises. Elicit the answer that it is taking the placeof the oxygen that has been used.

� Ask pupils to suggest what happens to the carbon dioxide that is produced by theburning candle. Tell pupils that carbon dioxide dissolves in water.

Concrete preparation (2)� Measure the mass of a candle before and after burning. Work out the mass lost.

� Ask pupils to suggest what material is being burned when a candle is burning.Expect some pupils to say ‘the wick’. Explain that the wax melts, travels up thewick, evaporates into a gas and then burns with oxygen in the air. Some pupilsmay need to be convinced that the wax does not just melt. Explain that the candle gets smaller as it burns so the wax is being ‘used up’.

� Ask pupils to recall what happened to the mass of magnesium when it burned.Elicit the answer that mass increased.

� Ask pupils to explain why the two burning experiments produced different resultsin terms of mass.

� Remind pupils of ideas of oxygen joining to magnesium for a solid product withincreased mass.

� Lead the discussion to ideas of oxygen joining to carbon and hydrogen in thehydrocarbon wax of the candle to produce carbon dioxide and water.

� Ask pupils where carbon dioxide and water have gone. Elicit the answer that theyare now in the air, not in the candle, so that the candle has lost mass to the air.

➔ CatalystInteractivePresentations 3

➔ Teacher sheet

Equipmentcandle; top pan balance;heatproof mat


Bridging to the unit

Pupils look at photos about the use of oxygen in oxyacetylenewelding and/or cutting. Catalyst Interactive Presentations 3

Setting the context

Pupils work in groups tobrainstorm the question ‘Howdo we know that the aircontains oxygen?’


Demo of burning a candle floating ona Petri dish in a trough of water under an upside-down beaker to showthat some of the air is used up.


Measure the mass of a candle beforeand after burning. Ask pupils wherethe mass has gone.


H4 StartersThe story of burning

Concrete preparation (1)Teacher sheetEquipment� trough� 400 cm3 beaker� half Petri dish� candle (about 3 cm high)

1 Pour water into a trough to about 2 cm depth.

2 Stick a short candle onto a half Petri dish.

3 Float the candle and half Petri dish on the water.

4 Light the candle.

5 Place the beaker upside-down over the burning candle.

6 Wait for the candle to go out and the water to rise.

Ideas can be extended by measuring the rise in water level and using this tocalculate the approximate percentage of oxygen in the air. The calculationshould give an answer of about 20%.

7 If calculation of % oxygen in air is required, repeat the experiment, but thistime noting the following:

a = water height in beaker before candle goes outb = maximum water height in beaker after candle goes outc = total volume of beaker (400 cm3)% oxygen = 100 × (b – a) / (c – a)



H1aTeacher

activity notesScientists’ jobs

Running the activityChoose four people in the class to act out the roles of mystery guests on thepanel. The rest of the class will be the members of the audience. The teacheracts as the presenter.

Give job description cards from the Resource sheet to the panel members, whohave to keep their identities secret. Give an activity sheet to each pupil in theaudience. This sheet contains questions for members of the audience to ask.They can also devise their own questions.

Choose members of the audience to ask questions in turn. Each member of thepanel has a turn at answering all of their questions. You might like to have abrief tutorial with the panel beforehand to help them prepare their answers tothe questions on the activity sheet.

Each time, after the mystery guest has replied to their questions, the pupils inthe audience have to decide which job that member of the panel does. Amember of the audience can ask the member of the panel if they do aparticular job. The panel member can reply Yes or No. Members of the audiencecan then ask more questions before another has a try at guessing the job.

The winner in each case will be the first person to guess the mystery guest’s jobcorrectly.

PitfallsSome vetting of questions from the audience may be necessary. You may alsohave to suggest further questions yourself.

AnswersThe identities of panel members are given on the Resource sheet.


Type Purpose DifferentiationDiscussion Pupils learn about chemical processes in manufacturing by acting out a TV quiz show. Core

Resource

H-Teachers.qxd 08-Jun-04 1:45 PM Page 1

H1aActivity

CoreScientists’ jobs

In this activity, you are going to find out how people indifferent careers depend on chemical reactions to manufactureuseful products. You will act out a TV quiz show where youhave to guess the jobs of four mystery guests.

Your teacher will be the TV presenter, and will choose four of youto be the ‘mystery guests’ on the panel. Each of these four will begiven details of the job that they do. All of the jobs involvechemistry. The rest of the class will be members of the audience,and can ask each of the mystery guests in turn the questions listedbelow.

1 What is your name?2 What do you do each day?3 Has your job always existed?4 Why do we need people to do your job?

You may also think of other questions to ask the mystery guests tofind out what their jobs are.

After the first mystery guest has answered the questions, you willhave the opportunity to guess the job of this panel member. If theguess is wrong, more questions can be asked before anothermember of the audience has a guess at the job.

The winner each time is the first person to guess the mysteryguest’s job correctly.


H-Activities.qxd 08-Jun-04 1:43 PM Page 1

H1aActivityResourceScientists’ jobs


Name: Mick SlaterJob: Machine operator

‘The machine I operate seals the polythene bags around rolls of kitchenpaper. I suppose I would be out of a job, if it wasn’t for the chemistsat ICI. In 1933 these chemists heated up a gas called ethene underpressure and the molecules joined together to make long chains anda new white substance. That’s what we call polythene today. Wherewould we be without it?’

Name: Shahida BegumJob: Pharmacist

‘Our shop is very busy on a Saturday. It is not unusual for meto dispense over 100 drugs in one day. It is amazing to think that atthe time of Queen Victoria’s death in 1901, doctors had only aspirin or afew herbal remedies available to them. We handle a lot of antibiotics,which are very effective against bacterial infections. Alexander Flemingstarted it all in 1928. He discovered that Penicillium mould killed bacteria.Chemists were able to extract the first antibiotic drug, called penicillin.’

Name: Trish BarkerJob: Materials scientist

‘We make bristles for tooth brushes out of nylon. They have to bemade out of a material that retains its stiffness when it is wet. Partof my job is selecting the right material for the job. The chemicalprocess for making the first nylon was invented by Wallace Carothersat the DuPont Experimental Station, Delaware, in 1930.’

Name: Diana HillJob: Chemical engineer

‘I work in a factory that manufactures ammonia. One of my jobs is todesign systems for efficient production. We produce ammonia to makefertilisers. The process we use is called the Haber Process. In 1905,Fritz Haber discovered that iron speeds up the reaction betweennitrogen and hydrogen to make ammonia. Haber was really looking fornew ways of making explosives for war-time use, but this method ofmaking ammonia for fertilisers has actually saved people world-widefrom starvation.’


H1bTeacher

activity notesDevelopment of aspirin

Running the activityPupils read carefully the Resource sheet describing the development of aspirin.

They then use information from the Resource sheet to summarise the keystages in the development of aspirin.

Core: Pupils are given headings for their summary.

Extension: Pupils are expected to devise their own headings.

PitfallsSome pupils may need help to organise their summaries.

ICT opportunitiesPupils could search the Internet for further information about aspirin.

AnswersMark the summaries by impression. Pupils should include essential informationunder each heading and not include irrelevant information.


Type Purpose DifferentiationPaper Pupils look at the origins of the drug aspirin, and the key stages in the development of

its use a patent medicine.Core (Extension)


Resource

Sheet 1 of 1

ActivityExtensionH1b Development of aspirin

Aspirin is possibly the most widely taken medicine in the world. In thisactivity, you will look at the origins of the drug, and the key stages inthe development of its use as a patent medicine.

Read carefully the Resource sheet describing the development of aspirin.

When any new product is developed, progress is made through a numberof stages from discovery through to sale to the public.

Use information from the Resource sheet to summarise the key stages inthe development of aspirin.

Give a heading, followed by a brief description, for each crucial stage inthe development of aspirin.


H1bActivity

CoreDevelopment of aspirin

Aspirin is possibly the most widely taken medicine in the world. In thisactivity, you will look at the origins of the drug, and the key stages inthe development of its use as a patent medicine.

Read carefully the Resource sheet describing the development of aspirin.

When any new product is developed, progress is made through a numberof stages from discovery through to sale to the public.

Use information from the Resource sheet to summarise the key stages inthe development of aspirin.

You should write your summary under the following headings.

DiscoveryMaking an effective productMass productionTestingMarketing the product



H1bActivityResourceDevelopment of aspirin

The story of the drug aspirin began over 2000 years ago. In ancient Greece,Hippocrates gave women willow leaf tea to relieve the pain of childbirth.

The modern use of aspirin began in 1763 when Reverend Edward Stone ofChipping Norton near Oxford used dried willow bark to relieve the symptomsof some of his parishioners who were suffering from rheumatic fever. ReverendStone described his findings in a letter to the Royal Society of London.

In 1823, the active ingredient was extracted from willow by chemists in Italy.They named the compound salicin.

French scientists made salicylic acid from salicin in 1853. Salicylic acid wasmass-produced and sold to the public. It was effective in reducing pain andlowering the temperature of fevers, but was found to irritate the digestive system.

German scientists working in 1893 made a small chemical change to salicylicacid – they added another molecule. The new compound, called acetylsalicylic acid, caused much less irritation of the digestive system.

In 1897, a scientist called Felix Hoffmann, working in the laboratories of a largeGerman company called Bayer & Co., developed and got a patent for the processfor producing acetyl salicylic acid or aspirin on a large scale. It is said that he firsttried out aspirin on his father, who suffered from arthritis.

Clinical trials were then carried out. Aspirin was tested on human volunteersto see how effective it was at relieving pain, lowering temperature and reducinginflammation, and to see if it had any unwanted side-effects.

After the clinical tests were successfully completed, aspirin was launchedfor sale in 1899.

The product was soon used by many leading doctors. They prescribed it totheir patients and reported on its beneficial effects. As more doctors supportedits use, the drug became more popular.

Since then aspirin has become the favourite drug to relieve pain. It also reducesthe excess body temperature that accompanies many infections, and reducesinflammation. In addition to being sold as aspirin tablets, the drug is containedin many other remedies. More recently, aspirin has also been discovered to haveother benefits, such as reducing strokes and heart attacks.

Glossaryactive ingredient the only substance in a mixture that has an effect on the symptoms

clinical trials the testing of a new drug on volunteers

patent a document giving the right to own an invention or process so noone else can use it without paying for the right



H2aTeacher

activity notesMeasuring energy changes

Running the activityPupils use a measuring cylinder to measure copper sulphate solution into a polystyrene cup.

They use a thermometer to measure the temperature of this solution before and afterstirring in a spatula measure of a metal powder.

In turn, iron filings, magnesium powder and zinc powder are added, each to a freshsolution of copper sulphate.

Results are noted in a table.

Core: Pupils are provided with a blank results table to copy.

Extension: Pupils devise their own table format.

Expected outcomesCore/Extension: Pupils find that the order of size of temperature rise follows the order of theadded metals in the reactivity series.

PitfallsThe amount of powder added and/or the volume of copper sulphate solution used mayhave to be modified to give a significant temperature change.

Pupils who are slow to place the polystyrene lid on the cup may lose much of the heatenergy released into the air.

Pupils may need to be reminded to record the highest temperature reached.

Safety notesPupils must wear eye protection.

Copper sulphate is very poisonous. Care should be taken that none enters the mouth.Hands should be washed when the activity has been completed.

Magnesium powder is flammable, and must be kept away from Bunsen flames.

The magnesium powder must be kept securely to avoid theft; especially a problem if pupilshave seen the thermite reaction.

AnswersCore:

1 Order of metals: magnesium, zinc, iron.

2 A polystyrene cup and lid were used to reduce heat loss into the air.

3 The order of the metals is the same as that in the reactivity series.

Extension:

1 – 3 As Core.

4 The greater the difference in reactivity between the metal of the powder and the copperin solution, the more energy is released when they react in the displacement reaction.More energy raises the temperature of the mixture to a higher value.

5 Mg + CuSO4 → Cu + MgSO4Zn + CuSO4 → Cu + ZnSO4


Type Purpose DifferentiationPractical Pupils measure the energy changes for some metal displacement reactions. Core, Extension


H2aTechnician

activity notesMeasuring energy changes

EquipmentFor each group:

� polystyrene cup� polystyrene lid� –10 to 50°C thermometer� 250 cm3 beaker� 50 cm3 measuring cylinder� fine iron filings� magnesium powder� zinc powder� copper sulphate solution

The copper sulphate solution should be 0.4 mol/dm3.Iron filings must be as fine as possible.

For your informationRunning the activityPupils use a measuring cylinder to measure copper sulphate solution into apolystyrene cup.

They use a thermometer to measure the temperature of this solution before andafter stirring in a spatula measure of a metal powder.

In turn, iron filings, magnesium powder and zinc powder are added, each to afresh solution of copper sulphate.

Results are noted in a table.

Core: Pupils are provided with a blank results table to copy.

Extension: Pupils devise their own table format.

Expected outcomesCore/Extension: Pupils find that the order of size of temperature rise follows theorder of the added metals in the reactivity series.

PitfallsThe amount of powder added and/or the volume of copper sulphate solutionused may have to be modified to give a significant temperature change.

Pupils who are slow to place the polystyrene lid on the cup may lose much ofthe heat energy released into the air.

Pupils may need to be reminded to record the highest temperature reached.

Safety notesPupils must wear eye protection

Copper sulphate is very poisonous. Care should be taken that none enters themouth. Hands should be washed when the activity has been completed.

Magnesium powder is flammable, and must be kept away from Bunsen flames.

The magnesium powder must be kept securely to avoid theft; especially aproblem if pupils have seen the thermite reaction.


Type Purpose DifferentiationPractical Pupils measure the energy changes for some metal displacement reactions. Core, Extension

H-Technician.qxd 26-May-04 11:56 AM Page 1

H2aActivity

CoreMeasuring energy changes

When chemical reactions take place, thermal energy is often given out. In this activity, you will measure the energy changes for some metal displacement reactions.

Equipment

� polystyrene cup � fine iron filings� polystyrene lid � magnesium powder� –10 to 50°C thermometer � zinc powder� 250 cm3 beaker � copper sulphate solution� 50 cm3 measuring cylinder

Obtaining evidence

11 Copy this table for your results.

2 Use a measuring cylinder to measure 50 cm3 of copper sulphate solution into apolystyrene cup.

3 Use a thermometer to measure the temperature of this solution. Note this down.4 Pour one spatula measure of fine iron filings into this copper sulphate solution.

Immediately place the polystyrene lid on the cup.5 Insert the thermometer through the hole in the polystyrene lid and gently stir the

mixture.6 Observe the highest temperature that the thermometer shows. Note this down.7 Wash out the polystyrene cup.8 Repeat the experiment using magnesium powder instead of iron filings, and then repeat

again using zinc powder. Use a fresh 50 cm3 of copper sulphate solution each time.

Considering the evidence

1 Place the three metals, iron, magnesium and zinc, in order of the size of temperaturechange, from largest to smallest.

Evaluating

2 During this experiment heat given out in the reaction is lost into the air. How did youmake sure that as little as possible of this heat was lost from the mixture?

3 Look at your answer to 1 . What is the connection between your answer and thereactivity series of metals?


Wear eyeprotection.

Copper sulphateis very poisonous.Care should be

taken that none enters themouth. Hands should bewashed when the activityhas been completed.

Solid Temperature Highest Temperaturemetal at start (°C) temperature change (°C)used reached (°C)

iron

magnesium

zinc

thermometer–10 to 50 °C

polystyrenefoam cupand lid

reactionmixture

beaker


H2aActivity

ExtensionMeasuring energy changes

When chemical reactions take place, thermal energy isoften given out. In this activity, you will measure theenergy changes for some metal displacement reactions.

Equipment� polystyrene cup � fine iron filings� polystyrene lid � magnesium powder� –10 to 50 °C thermometer � zinc powder� 250 cm3 beaker � copper sulphate solution� 50 cm3 measuring cylinder

Obtaining evidence1 Draw a table to record your results. Show the change in

temperature for each of the three experiments.2 Use a measuring cylinder to measure 50 cm3 of copper

sulphate solution into a polystyrene cup.3 Use a thermometer to measure the temperature of this

solution. Note this down.4 Pour one spatula measure of fine iron filings into this copper

sulphate solution. Immediately place the polystyrene lid on the cup.5 Insert the thermometer through the hole in the polystyrene lid and gently stir the

mixture.6 Observe the highest temperature that the thermometer shows. Note this down.7 Wash out the polystyrene cup.8 Repeat the experiment using magnesium powder instead of iron filings, and then repeat

again using zinc powder. Use a fresh 50 cm3 of copper sulphate solution each time.

Considering the evidence1 Place the three metals, iron, magnesium and zinc, in order of the size of temperature

change, from largest to smallest.

Evaluating2 During this experiment heat given out in the reaction is lost into the air. How did

you make sure that as little as possible of this heat was lost from the mixture?3 Look at your answer to 1 . What is the connection between your answer and the

reactivity series of metals?4 Use ideas of reactivity of metals to explain the differences in temperature increase in

the three experiments.5 The symbol equation for the first reaction is

Fe + CuSO4 → Cu + FeSO4

Write symbol equations for the other two reactions.


thermometer–10 to 50 °C

polystyrenefoam cupand lid

reactionmixture

beaker

Wear eyeprotection.

Copper sulphateis very poisonous.Care should be

taken that none enters themouth. Hands should bewashed when the activityhas been completed.


H2bTeacher

activity notesThe right fuel for the job

Running the activityCore:

Resource sheets 1 and 2 contain nine ‘challenges’. Each challenge is about theuse of one particular fuel or a number of fuels.

Resource sheets 3 and 4 contain some details about different fuels.

Pupils use the information in Resource sheets 3 and 4 to answer the questionson one of the nine challenges.

The challenges vary in difficulty, so use your knowledge of the class to assignthe challenges appropriately. Challenges 1–3 are the easiest. The pupils shouldbe given a limited amount of time before feeding back to the class.

Extension:

More able pupils may be given the more difficult challenges (7–9).

PitfallsSome pupils may need guidance in matching fuel to job.

AnswersChallenge 1

1 dung

Challenge 2

1 Burn the peat to heat home and cook.2 Yes – it is their traditional way and traditional crafts should be preserved as

part of history or no – it is destroying the peat bog habitat and they havealternative methods of heating, e.g. electricity.

Challenge 3

1 Petrol, diesel, rape seed oil fuel, methane, propane, ethanol, hydrogen.2 Hydrogen – all the others produce carbon dioxide when they burn.3 Explosive when mixed with oxygen; a gas so difficult to store and transfer.

Challenge 4

1 All the solids: peat, smokeless fuel, wood, charcoal, dung, blubber, coal.2 blubber

Challenge 5

1 Both liquids, both made from crude oil, both burn to give carbon dioxideand water.

2 High energy, but expensive and only available at airports or in largeamounts from a supplier.

3 Easily available from petrol stations and cheaper than kerosene, but has lessenergy.


Type Purpose DifferentiationPaper Pupils learn about the properties of different fuels by matching fuels to uses. Resource 1

Resource 2Resource 3Resource 4


H2bTeacher

activity notesThe right fuel for the job (continued)

Challenge 6

1 Not able to plant and grow crops, not able to harvest wood and othermaterials that grow locally.

2 Would have to make the methane from rubbish; harder to store because it isa gas; need a special burner/cooker to burn methane, not just a fire.

Challenge 7

1 The supply is unreliable, particularly in bad weather.2 Coal, smokeless fuel, fuel oil, propane, methane, wood.3 The liquids and gases: fuel oil, propane and methane.4 The solids: coal, smokeless fuel, wood.5 Methane and propane, as these produce only carbon dioxide and water

when burned.6 Not methane as no gas supply. Smokeless fuel is too expensive and it would

not be in a smokeless zone if isolated. Any other choice is acceptable if pupilgives reasons, e.g. propane because it is so clean, wood because it is locallyavailable, coal because it is easier to store than propane, fuel oil because it iseasy to pipe from an underground storage tank.

Challenge 8

1 Methane, propane (gas burner type cookers), coal, smokeless fuel, fuel oil,wood (Aga-type cookers).

2 propane3 Not methane, as no gas supply. Not a solid fuel, as bulky and difficult to

store. Not fuel oil, as too bulky. Propane is available in quite small, portabletanks (e.g. Calorgas).

Challenge 9

1 Petrol, diesel, propane, methane, ethanol, rape seed oil fuel, hydrogen.2 petrol3 Not an experimental fuel, as this would make the car too expensive, so not

hydrogen or rape seed oil fuel. Not a fuel that needed the car to be speciallymodified to make it run, like methane, propane and ethane. Not diesel, asthis turns into a solid at low temperatures. That leaves petrol.



H2bActivity

Resource 1The right fuel for the job

Challenge 1

You are a Bedouin tribesman. The Bedouins are nomads who live in the deserts ofnorthern Africa. There are no trees in the desert and you have no machines. Thereis no electricity, and no piped fuels. All your wealth is in your camels and yourother animals.

1 Which fuel would you use?

Challenge 2

You live in an isolated part of Ireland. You do have electricity, but you think it isvery expensive. Your father and grandfather worked as peat-cutters. Lately a youngman has been talking to you about conserving the peat but you think a few local‘cottagers’ should be allowed to continue using it.

1 How do the cottagers use the peat?2 Do you think they should be allowed to keep using it?

Challenge 3

You are an engineer in the future designing a car. In the future, there are no fossilfuels because we have used them all up. This means there is no crude oil. It isillegal to use a fuel that produces any pollution when it burns, even carbon dioxide.

1 What fuels are used in cars today?2 Which of these fuels will the engineer choose? Give your reasons.3 What are the disadvantages of this type of fuel?

Challenge 4

You are an Inuit living in Alaska. The ground is frozen all year round and no plantsgrow. You are an excellent hunter. You think that Inuits should live in the traditionalway, so you do not use much technology. There is no electricity supply in your area.

1 What fuels can be used to make a traditional fire?2 Which of these fuels would you use as the Inuit hunter?

Challenge 5

You are an engineer designing a small aircraft. You want ordinary people who livein isolated areas to buy the aircraft. You have to decide between using kerosene orpetrol for the fuel.

1 In what ways are kerosene and petrol alike?2 What are the advantages of kerosene? Does it have any disadvantages?3 What are the advantages of petrol? Does it have any disadvantages?



H2bActivity


Challenge 6

You are an African tribeswoman. Your people have always used wood astheir fuel. A scientist has told you that trees are needed to keep the soiltogether and stop it being washed away in the rains. The scientist wantsyou to use waste to make methane and burn that.

1 What will happen if all the soil is washed away?2 What would be the problems of using methane instead of wood?

Challenge 7

You have moved into an old, isolated house that has no boiler or centralheating. The local people tell you stories about how the electricity supply tothe houses can be cut off for days after a storm. There is no natural gassupply to the house, because it is so isolated. You are going to install aboiler and central heating.

1 Why is electricity a poor choice for heating this house?2 Which fuels are used to heat water in houses?3 Which of these fuels could be piped into the boiler?4 Which of these fuels would be tipped or shovelled into the boiler?5 Which of these fuels is the cleanest? Give your reasons.6 Which fuel would you use to heat the isolated, old house? Explain your

decision.

Challenge 8

You design caravans and motor homes. A modern caravan or motor homehas lots of appliances, including a cooker. You want the cooker to workeverywhere, even if there is no electricity or natural gas supply.

1 What fuels are used in cookers?2 What fuel would you choose for this cooker?3 Explain why you chose this fuel rather than any of the others.

Challenge 9

You live in northern Finland. During the winter, it is very cold. You arebuying a new car.

1 Which fuels can be used in cars?2 Which of these fuels would you choose for a car in northern Finland?3 Explain why you chose this fuel and rejected the others.



H2bActivity



Propane� Gas (but liquid when in the storage tank).� Made from crude oil. Crude oil is found deep in the

ground and has to be drilled for.� Used in boilers to heat water, and in fires and for

cookers. It is more expensive than natural gas and isonly used by people who do not have gas pipescoming to their homes. It is supplied in large bottlesor tanks. Cars, lorries and buses can be altered sothey will run on propane.

� A very clean fuel, producing no smoke and ash. Itproduces carbon dioxide and water when burned.

Ethanol� Liquid.� Made from sugar by fermentation.� Can be used as a fuel for cars. It is cheaper than

petrol in countries that have big factories that make it (like Brazil). The cars have to be modified to run on ethanol.

� Ethanol is a clean fuel. It produces only carbon dioxide and water when burnt.

Paraffin� Liquid.� Made from crude oil by an expensive process.

Crude oil is found deep in the ground and has to be drilled for.

� Paraffin is used mainly in small heaters. It is about the same price as fuel oil.

� A smoky fuel but makes no ash. It burns to makecarbon dioxide and water.

Rape seed oil fuel� Liquid.� Made from rape seed oil.� Fuel made from rape seed oil is still experimental.

It is very like diesel and it can be used in lorries andcars as fuel.

� A clean fuel that burns producing mainly carbondioxide and water.

Hydrogen� Gas.� Made from water.� Cars have been made that use hydrogen as a fuel,

but they are still experimental. Hydrogen is quitecheap, but is very explosive when mixed with oxygen and must be stored at very low temperature.

� Hydrogen is a very clean fuel – it produces only water when burned.

Coal� Solid.� A fossil fuel that has to be dug out of the ground

by miners.� Used in boilers for heating water, or for fires. Less

expensive than fuel oil, more expensive than natural gas.

� Most coal burns to make unpleasant gases likesulphur dioxide. Carbon dioxide, water, smoke andash are also produced.

Peat� Found just below the surface and is very easy to

dig up.� Peat is dried out and burnt as a fuel. By digging it

up people are destroying peat bogs. Peat bogs are very rare and have a unique set of plants and animals found on them.

� Burns to give carbon dioxide, water, ash and lots of smoke.

Methane� Gas.� Found underground or made from rotting rubbish.

Methane from underground is called natural gas and has to be drilled for.

� Used in boilers to heat water, in fires and for cookers. It can be used as a fuel in cars and buses,but these have to be modified to use it. It is cheaperthan coal or fuel oil.

� A very clean fuel, producing no smoke or ash. Itproduces carbon dioxide and water when burned.

Smokeless fuel� Solid.� Made from coal.� Used in boilers for heating water, and for fires.

More expensive than coal, fuel oil or natural gas.� Burns with little smoke, so it can be used in

‘smokeless zones’. Makes carbon dioxide, water and a small amount of unpleasant gases like sulphur dioxide when it burns. Burns to ash.


H2bActivity



Kerosene� Liquid.� Make from crude oil by an expensive process. Crude

oil is found underground and has to be drilled for.� Used in aeroplanes because it turns into gas easily

in the engine. It is very high in energy. It is veryexpensive. Airports buy tankers of kerosene fromsuppliers and owners of small planes buy theirkerosene from airport owners.

� Burns to give mainly carbon dioxide and water.

Fuel oil� Liquid.� Made from crude oil by an expensive process. Crude

oil is found deep in the ground and is drilled for.� Used in boilers for heating water. Usually more

expensive than natural gas (methane) or coal.� Produces unpleasant gases like sulphur dioxide

when it burns, as well as carbon dioxide and water.Can be smoky.

Petrol� Liquid.� Made from crude oil by an expensive process.


� Used in cars because it turns into petrol gas very easily in the engine. This means it works even at lowtemperatures. Petrol is available from petrol stations all over the country.

� Burns to give mainly carbon dioxide and water.

Diesel� Liquid.� Made from crude oil by an expensive process.


� Used in cars and lorries because it can be turned into gas in the engine. Does not work at lowtemperatures as it turns into a solid. It is cheaper than petrol.

� Burns to give mainly carbon dioxide and water, butcan make smoke.

Charcoal� Solid.� Made from wood.� Use mainly for barbecues. Expensive.� Burns with little smoke and little ash. Burns at a very

high temperature. Produces carbon dioxide and water when it burns.

Blubber� Solid.� Blubber is the fat from seals. Seal fat is a thick layer

under the skin. It is only available to people who hunt seals.

� Blubber can be burned in fires.� It is a smoky fuel. Carbon dioxide and water are

produced when it burns.

Dung� Solid.� Made from animal droppings. The droppings are

collected and dried.� Used in fires. It is cheap because the droppings are

a waste product.� Makes smoke and ash when burning. Produces

mainly carbon dioxide and water.

Wood� Solid.� Collected from woods or forests, or bought.� Used in boilers to heat water, and for fires.� Can be cheap if collected by the person who is

going to burn it. Less cheap if it has to be bought.� Makes lots of smoke and ash when burning.


H3aTeacher

activity notesWhat happens to the mass?

Running the activityPupils pour two solutions into different test tubes, stand them in a beaker andfind their combined mass. The solutions are then mixed and the massmeasured again. Any changes in appearance are noted. Three differentreactions are studied. In the third reaction the temperature of solutions andfinal mixture are also measured.

Expected outcomesIn each of the three experiments pupils will find that the mass of reactants isthe same as the mass of the products (to within the limits of accuracy of themeasurements). They will observe formation of a white precipitate in the firstreaction, formation of a pink colour in the second (the indicator changescolour as conditions go from acid to alkaline), and a rise in temperature in thethird.

PitfallsPupils may spill some of the mixture whilst mixing and then get a spuriousdecrease in mass. A small mass change may be noted in the third reaction,caused by some liquid being lost on the thermometer. Pupils should be guidedas to what is a significant change in mass and what is acceptable experimentalerror.


Barium nitrate is poisonous. Contact with the mouth should be avoided.

Answers1 The first two reactions involved a change in appearance (formation of

precipitate, change of indicator colour) and the third involved a change intemperature.

2 None of the three reactions involved a significant change in mass.

3 An observable change each time showed that a new substance was formed,and therefore a chemical reaction had taken place.

4 In a chemical reaction the mass of the products is equal to the mass of thereactants.


Type Purpose DifferentiationPractical Pupils learn that the mass of the products of a chemical reaction is the same as the

mass of the reactants.Core


H3aTechnician

activity notesWhat happens to the mass?


� six test tubes� 250 cm3 beaker� –10 to 50°C thermometer� sodium sulphate solution� barium nitrate solution� citric acid solution� potassium hydroxide solution� hydrochloric acid� sodium hydroxide solution� phenolphthalein solution� access to a top pan balance

Normal bench concentrations of reagents may be used (1.0 mol/dm3).

For your informationRunning the activityPupils pour two solutions into different test tubes, stand them in a beaker andfind their combined mass. The solutions are then mixed and the massmeasured again. Any changes in appearance are noted. Three differentreactions are studied. In the third reaction the temperature of solutions andfinal mixture are also measured.

Expected outcomesIn each of the three experiments, pupils will find that the mass of reactants isthe same as the mass of the products (to within the limits of accuracy of themeasurements). They will observe formation of a white precipitate in the firstreaction, formation of a pink colour in the second (the indicator changescolour as conditions go from acid to alkaline), and a rise in temperature in the third.

PitfallsPupils may spill some of the mixture whilst mixing and then get a spuriousdecrease in mass. A small mass change may be noted in the third reaction,caused by some liquid being lost on the thermometer. Pupils should be guidedas to what is a significant change in mass and what is acceptable experimentalerror.


Barium nitrate is poisonous. Contact with the mouth should be avoided.


Type Purpose DifferentiationPractical Pupils learn that the mass of the products of a chemical reaction is the same as the mass of

the reactants.Core

H-Technician.qxd 26-May-04 11:56 AM Page 2

H3aActivity

CoreWhat happens to the mass?

When a chemical reaction takes place one or more changesoccur. These may include changes in appearance andtemperature. In this activity you will find out what happens to the mass of the reactants and products.

Equipment

� six test tubes � potassium hydroxide solution� 250 cm3 beaker � hydrochloric acid� –10 to 50 ºC thermometer � sodium hydroxide solution� sodium sulphate solution � phenolphthalein solution� barium nitrate solution � access to a top pan balance� citric acid solution

Obtaining evidence

1 Copy the table and use it to record your results.

2 Pour sodium sulphate solution into a test tube until about one-quarter full. Stand this test tube in a 250 cm3 beaker sothat it does not fall over.

3 Pour barium nitrate solution into a second test tube until thisalso is about one-quarter full. Stand this test tube in the samebeaker.

4 Use a top pan balance to measure the mass of the beaker,including the test tubes and solutions. Note down this massbefore the reaction.

5 Pour the liquid in one test tube into the liquid in the other testtube. Mix the two solutions by holding the top of the test tube firmly with one hand and tapping the bottom of the testtube sharply with a finger of the other hand. Be careful not tospill any of the mixture. Note down any changes that youhave seen. Also note down if the tube begins to feel hot.


Wear eyeprotection.

Barium nitrateis poisonousand care

should be taken that itdoes not enter themouth.

Solutions Mass Mass Other observationsbefore after or measurements

sodium sulphate and barium nitrate

citric acid and potassium hydroxide

hydrochloric acid and sodiumhydroxide


H3aActivity

CoreWhat happens to the mass? (continued)

6 Place both test tubes back into the beaker and measure themass of beaker, tubes and mixture. Note down this mass afterthe reaction.

7 Using two clean test tubes, repeat steps 2 to 6, but this timeuse a solution of citric acid to which you have added a fewdrops of the indicator phenolphthalein in one test tube, and asolution of potassium hydroxide in the other test tube.Phenolphthalein is colourless in acid and pink in alkali.

8 Using two clean test tubes, repeat steps 2 to 6, but this timeuse a solution of hydrochloric acid in the one test tube and asolution of sodium hydroxide in the other test tube. Before youmeasure the mass each time, use a thermometer to measurethe temperature of the solutions and of the mixture.


1 In each of these three chemical reactions the reactantschanged to form the products. In which reactions did thisinvolve a change in appearance? In which reaction was achange in temperature involved?

2 Did any of the three reactions involve a significant change in mass?

3 How do you know that a chemical reaction took place each time?

4 Write a sentence about the mass of reactants and the mass ofproducts in a chemical reaction.



H3bTeacher

activity notesBurning magnesium

Running the activityCore: Pupils burn a known mass of magnesium in a crucible. They find the mass of magnesium oxideformed, and from this the mass of oxygen that joined to the magnesium in the reaction.

Help: Provides a table in which to enter results and make calculations.

Extension: Pupils are expected to organise their own recording of results and calculations.

Other relevant materialSkill sheet 34: Balancing equations

Expected outcomesCore: Pupils will relate their mass measurements and calculations to the idea that, in a chemical reaction,the mass of reactants is always the same as the mass of the products.

Help: Pupils calculate the masses of product and of oxygen that reacted with the magnesium. They realisethat the ‘extra’ mass in the magnesium oxide has come from the air.

Extension: Pupils relate their mass measurements and calculations to the Law of Conservation of Mass.

PitfallsIf the crucible lid is lifted too high or removed too early, much of the magnesium oxide will be lost into the air.

If not enough air is admitted to the crucible, some of the magnesium will remain unburned. It is best to windthe magnesium ribbon around a pencil to form a coil that will allow better contact with air in the crucible.

Safety notesMagnesium burns with a very hot and bright flame. Do not allow pupils to burn the magnesium ribbon infree air.

The crucible will get very hot during the experiment. It will need to stand for several minutes before it cansafely be handled.

AnswersCore:

1 Magnesium is a shiny silver metal. The product of the reaction (magnesium oxide) is a dull grey powder.2 The magnesium oxide had a higher mass than the magnesium.3 The extra mass was oxygen from the air.4 The mass of the product, magnesium oxide, was the same as the combined mass of the two reactants,

magnesium and oxygen.5 magnesium + oxygen → magnesium oxide

Help:

1 Shiny, silver metal. 2 Dull, grey powder.3 The product (magnesium oxide) weighed more than the magnesium that was burned.4 The extra mass came from (oxygen in) the air.

Extension:

1 – 5 As Core. 6 Yes. The magnesium and oxygen atoms always join together in the same ratio, 1:1.7 During a chemical reaction mass is neither lost nor gained. 8 2Mg + O2 → 2MgO


Type Purpose DifferentiationPractical Pupils burn magnesium and measure the increase in mass. They relate this to the Law of

Conservation of Mass.Core (Extension)Help

H-Teachers.qxd 21-Jul-04 3:58 PM Page 7

H3bTechnician

activity notesBurning magnesium


� magnesium ribbon � Bunsen burner� crucible and lid � heatproof mat� pipe clay triangle � tongs� tripod � access to a top pan balance

The magnesium ribbon should be cleaned with abrasive paper and cut into10 cm strips.

Other relevant materialSkill sheet 34: Balancing equations

For your informationRunning the activityCore: Pupils burn a known mass of magnesium in a crucible. They find the massof magnesium oxide formed, and from this the mass of oxygen that joined tothe magnesium in the reaction.

Help: Provides a table in which to enter results and make calculations.

Extension: Pupils are expected to organise their own recording of results andcalculations.

Expected outcomesCore: Pupils will relate their mass measurements and calculations to the ideathat, in a chemical reaction, the mass of reactants is always the same as themass of the products.

Help: Pupils calculate the masses of product and of oxygen that reacted with themagnesium. They realise that the ‘extra’ mass in the magnesium oxide hascome from the air.

Extension: Pupils relate their mass measurements and calculations to the Law ofConservation of Mass.

PitfallsIf the crucible lid is lifted too high or removed too early, much of themagnesium oxide will be lost into the air.

If not enough air is admitted to the crucible, some of the magnesium willremain unburned. It is best to wind the magnesium ribbon around a pencil toform a coil that will allow better contact with air in the crucible.

Safety notesMagnesium burns with a very hot and bright flame. Do not allow pupils toburn the magnesium ribbon in free air.

The crucible will get very hot during the experiment. It will need to stand forseveral minutes before it can safely be handled.


Type Purpose DifferentiationPractical Pupils burn magnesium and measure the increase in mass. They relate this to the Law of

Conservation of Mass.Core (Extension)Help

H-Technician.qxd 21-Jul-04 4:04 PM Page 3

H3bActivity

CoreBurning magnesium

Magnesium metal burns in air to form the compound magnesiumoxide. In this activity you will find what happens to the mass of themagnesium as it reacts with oxygen to form magnesium oxide.

Equipment� magnesium ribbon � tripod � tongs� crucible and lid � Bunsen burner � access to a top pan� pipe clay triangle � heatproof mat balance

Obtaining evidence1 Weigh the crucible and its lid. Note down this mass.2 Take a 10 cm piece of clean magnesium ribbon.

Fold it or coil it so that it will fit into the crucible.3 Weigh the crucible, lid and magnesium. Note down

the mass.4 Place the crucible containing the magnesium, with its lid, on a pipe clay triangle.5 Use a Bunsen burner to heat the crucible. Heat gently at first, then strongly.6 Every few minutes use tongs to lift the crucible lid a little. If the magnesium flares up,

put the lid back down. When no flaring is seen, remove the lid and place it on aheatproof mat.

7 Stop heating and leave the crucible to cool.8 Re-weigh the crucible, lid and contents. Note down this mass.9 Use your mass measurements to calculate the following values:

� mass of magnesium � mass of oxygen in the magnesium oxide.� mass of magnesium oxide

Considering the evidence1 Describe the difference in appearance of the magnesium before burning and the

magnesium oxide produced afterwards.2 How did the mass of the magnesium oxide differ from the mass of magnesium that

was burned?3 Where did this extra mass come from?4 The mass of the products of a reaction is the same as the mass of reactants. Explain

how this is true for the burning of magnesium.5 Write a word equation for the reaction of magnesium with oxygen.

6 This experiment could be repeated using different massesof magnesium. Would you expect the ratio of mass ofmagnesium to mass of oxygen (in the magnesium oxide)to be the same each time? Explain why.

7 The relationship of mass of products and mass of reactants is described in the Law ofConservation of Mass. This law applies to all reactions. Suggest what this law says.

8 Write a symbol equation for the reaction of magnesium with oxygen.


Wear eyeprotection.

In thisexperiment thecrucible gets

very hot. After heating,you must allow it to coolfor several minutes, untilit can be handled safely.

crucible lidcrucible

magnesium ribbon

tripod

pipe clay triangle

heat

Extension


H3bActivity

HelpBurning magnesium

Use this sheet to record your results and do mass calculations.

Presenting the results

1 Record your results in the mass column below.

2 Complete the bottom three rows of the mass column in thetable by working out the mass of magnesium used, the massof magnesium oxide made, and the mass of oxygen in thismagnesium oxide.

The ‘calculation’ column in the table shows you how to workthese out using the masses from the other rows.



1 What did the magnesium look like before it was burned?2 What did the product look like after the magnesium had been

burned?3 Did the product, magnesium oxide, weigh more or less than the

magnesium that you burned?4 Where did this extra mass come from?

Items on top pan balance Mass Calculation Row letter

crucible and lid a

crucible, lid and magnesium b

crucible, lid and magnesium oxide c

magnesium b – a d

magnesium oxide c – a e

oxygen in magnesium oxide e – d


H4aTeacher

activity notesCombustion of a candle

Running the activityCore/Extension: A pump is used to draw the gases produced by a burning candlethrough the apparatus. After a few seconds the limewater goes cloudy as carbondioxide reacts with the calcium hydroxide to produce a white precipitate. After afew minutes the pump is turned off, and the U-tube disconnected. Water hascondensed in the U-tube. Anhydrous copper sulphate turns from white to blue,proving that this liquid is water.

Other relevant materialCatalyst Interactive Presentations 3 contains an animation of this demonstration,should you wish to avoid a practical demonstration.

Skill sheet 34: Balancing equations

Expected outcomesCore: Pupils will learn that candle wax burns to produce the products carbondioxide and water. They will write a word equation for the reaction.

Extension: Pupils will also write a symbol equation for the reaction. They willextend ideas of combustion to produce carbon dioxide and water to otherhydrocarbons.

PitfallsAfter the pump has been run for a few minutes with the candle alight, theprecipitate in the limewater will disappear. This happens because insolublecalcium carbonate reacts with more carbon dioxide (and water) to produce solublecalcium hydrogen carbonate. You may wish to explain this to more able pupils.

The pump must be run for about 10 minutes with the candle alight for areasonable amount of water to collect in the U-tube.

If the filter funnel is positioned too close to the candle, the air supply is restricted.Some incomplete combustion takes place introducing soot into the apparatus.

Safety notesThe inverted funnel may shatter when heated by the candle flame. Use a ‘Pyrex’type funnel and lower it slowly over the flame allowing it to heat up uniformly.

AnswersCore:

1 The limewater went cloudy.2 This shows that carbon dioxide was produced by the burning candle.3 A colourless liquid.4 The anhydrous copper sulphate changed from white to blue.5 This shows that water was produced by the burning candle.6 hydrocarbon + oxygen → carbon dioxide + water

Extension:

1 – 6 As Core. 7 C25H52 + 38O2 → 25CO2 + 26H2O8 Carbon dioxide and water.


Type Purpose DifferentiationPractical Pupils are shown that the combustion of candle produces carbon dioxide and water. Core (Extension)

H-Teachers.qxd 21-Jul-04 3:58 PM Page 8

H4aTechnician

activity notesCombustion of a candle

EquipmentFor the demonstration:

� candle� glass filter funnel� U-tube� side arm tube� glass connecting tubes� limewater� ice� anhydrous copper sulphate

Other relevant materialCatalyst Interactive Presentations 3 contains an animation of this demonstration,should you wish to avoid a practical demonstration.

Skill sheet 34: Balancing equations

For your informationRunning the activityCore/Extension: A pump is used to draw the gases produced by a burning candlethrough the apparatus. After a few seconds the limewater goes cloudy as carbondioxide reacts with the calcium hydroxide to produce a white precipitate. Aftera few minutes, the pump is turned off, and the U-tube disconnected. Water hascondensed in the U-tube. Anhydrous copper sulphate turns from white to blue,proving that this liquid is water.

Expected outcomesCore: Pupils will learn that candle wax burns to produce the products carbondioxide and water. They will write a word equation for the reaction.

Extension: Pupils will also write a symbol equation for the reaction. They willextend ideas of combustion to produce carbon dioxide and water to otherhydrocarbons.

PitfallsAfter the pump has been run for a few minutes with the candle alight, theprecipitate in the limewater will disappear. This happens because insolublecalcium carbonate reacts with more carbon dioxide (and water) to producesoluble calcium hydrogen carbonate. You may wish to explain this to moreable pupils.

The pump must be run for about ten minutes with the candle alight for areasonable amount of water to collect in the U-tube.

If the filter funnel is positioned too close to the candle, the air supply isrestricted. Some incomplete combustion takes place, introducing soot intothe apparatus.

Safety notesThe inverted funnel may shatter when heated by the candle flame. Use a‘Pyrex’ type funnel and lower it slowly over the flame allowing it to heat upuniformly.


Type Purpose DifferentiationPractical Pupils are shown that the combustion of candle produces carbon dioxide and water. Core (Extension)

H-Technician.qxd 21-Jul-04 4:04 PM Page 4

H4aActivity

CoreCombustion of a candle

When a candle is lit the wax burns. In this demonstration you will find out whatproducts are made during this reaction.

Equipment

For the demonstration:

� candle � glass connecting tubes� glass filter funnel � limewater� U-tube � ice� side arm tube � anhydrous copper sulphate

Obtaining evidence

Your teacher will demonstrate an experiment using the apparatus shown in the diagram.

1 The pump is switched on to draw air through the apparatus. Air can be seen bubblingthrough the limewater. The candle is lit.

2 Look carefully what happens to the limewater. Note down what you see.3 After a few minutes the pump is switched off and the U-tube removed. Note down

what you can see in the U-tube.4 A spatula measure of anhydrous copper sulphate is added to the U-tube. Note down

what happens.5 Write a summary of what you observed during the experiment.


1 What change took place in the limewater?2 What does this prove about the products of combustion of the candle?3 What did you see in the U-tube?4 What happened to the anhydrous copper sulphate when it was added to the U-tube?5 What does this prove about the products of combustion of a candle?6 Candle wax is made of hydrocarbons.

Write a word equation for the complete combustion of a hydrocarbon.

7 One of the hydrocarbons in candle wax has the formula C25H52.Write a symbol equation for the complete combustion of this hydrocarbon.

8 Candle wax is a hydrocarbon, which means that it is a compound made from theelements carbon and hydrogen only.Petrol is a mixture of hydrocarbons. Suggest the products of combustion of petrol.


limewater

glasstube

glassfunnel U-tube

rubbertubing

to pump

candle

ice

Extension


H4bTeacher

activity notesThe discovery of oxygen

Running the activityPupils search the Internet to find information about the early theories ofcombustion (phlogiston theory) and the work of Joseph Priestley and AntoineLavoisier.

They summarise what they have found out in a time chart.

Some useful websites are suggested on the pupil sheet.

Other relevant materialSkill sheet 4: Web searches

Expected outcomesPupils will see how scientific ideas change as additional evidence is gained.

PitfallsSome pupils may have difficulty in deciding what information is relevant andirrelevant to the task.

Answers1 In the phlogiston theory it was thought that all combustible materials

contained a substance called phlogiston. When these materials were burnedthe phlogiston was thought to be given off. Presence of phlogiston in theair was then thought to make this air unable to support furthercombustion.

2 Both Priestley and Lavoisier thought that burning used up a gas that waspart of the air, so that when all of this gas had been used up substancescould no longer burn.

3 Antoine Lavoisier isolated a gas that reacted with substances as theyburned. As these substances burned they formed acidic products. Lavoisiertherefore named the gas oxygen, from the Greek words meaning ‘acidmaker’.


Type Purpose DifferentiationICT Pupils search the Internet for information about early theories of combustion and the

work of Priestley and Lavoisier.Core


H4bActivity

CoreThe discovery of oxygen

In this activity you will use the Internet to find information about theearly ideas of combustion, and the most important scientists involvedin the discovery of oxygen: Joseph Priestley and Antoine Lavoisier.

1 Use the Internet to search for information about early ideas of combustionand about the discovery of oxygen. Some useful websites are listed below:

Phlogiston TheoryInformation on Joseph PriestleyMore information on Joseph PriestleyInformation on Antoine LavoisierMore information on Antoine Lavoisier

2 Make notes about:

� early ideas of what happens when a substance burns: the ‘phlogistontheory’

� the experiments carried out by Joseph Priestley� the theories of combustion put forward by Joseph Priestley� the experiments carried out by Antoine Lavoisier� the theories of combustion put forward by Antoine Lavoisier� the discovery and naming of the gas oxygen

Make sure your information answers the questions below.

1 What is the ‘phlogiston theory’?2 How were the ideas of Priestley and Lavoisier different from this theory?3 Why did Lavoisier name his newly discovered gas oxygen?

3 Write a time chart to summarise what you have found out.



http://www.heinemann.co.uk/hotlinks/url.asp?urlid=9596






H1 PlenariesProducts from reactions

Review learning� Pupils work in groups or individually to match cards showing chemical

products with cards showing uses of these products.

� Pupils or groups in turn report their ‘matches’ for discussion by the class.Write correct matches on the board.

Sharing responses� Pupils work in groups of four. Each group is given a set of cards. Four cards

contain the jobs from Activity H1a, and the remainder contain products orother terms associated with these jobs.

� Pupils shuffle the product/term cards and deal them to the four members ofthe group.

� One job card chosen at random is placed on the desk.

� Pupils take turns to match a products/terms card to the job card.

� When no pupil in the group can find a card to match, the next job card ischosen at random and the process repeated.

� The winner is the first pupil to have no cards left.

� Groups report their ‘matches’ back to the class for discussion.

Group feedback� Choose one pupil to begin the reporting back of ideas from Activity H1b.

� Ask this pupil to read to the class the first part of his/her summary of the keystages in the development of aspirin.

� Discuss these ideas with the class to decide on a final summary to be writtenon the board.

� Choose a second pupil to continue the reporting back, and so on, until acomplete summary is on the board.

� Ask pupils to comment on which ideas are relevant only to the developmentof aspirin, and which are relevant to the development of all new products.

Word game� Pupils complete a word-search using words from the activities.

Looking ahead� Show pupils a video demonstrating a range of fuels being burned for

different uses.

� Ask pupils to comment on similarities and differences in the way thatdifferent fuels are used.

➔ Pupil sheet

➔ Pupil sheet

AnswersMachine operator:ethane, polythene,polymerisation, plasticPharmacist: drugs,aspirin, antibiotic,penicillinMaterials scientist:useful materials, hard-wearing, stiff, resistant to waterChemical engineer:ammonia, Fritz Haber,fertilisers, explosives

➔ Pupil sheet

Answersaluminium, ammonia,aspirin, combustion,fertiliser, food, Fritz,fuel, Haber, iron,polythene, rubber

➔ Catalyst InteractivePresentations 3


Review learning

Pupils match chemicalproducts with theiruses.

Sharing responses

Card game to use informationgained from Activity H1a tomatch the names of jobs tothe products produced.

Group feedback

Pupils report to the classtheir ideas from Activity H1b.These are summarised into aflow chart on the board.

Word game

Word-search usingwords from theactivities.

Looking ahead

Show video of burning and use of arange of fuels, e.g. natural gas,wood, coal, petrol, fuel oil.Catalyst Interactive Presentations 3

H-Plenaries.qxd 08-Jun-04 1:46 PM Page 1



Review learning

You have two sets of cards.

The first set contains a number of chemical products.

The second set contains some uses of these products.

Match each chemical product with one of the uses.

Write down your matched pairs so that you can report them back to the class.

Chemical products Uses

used to make car bodies

aluminium used to make car tyres

copper

used to make electrical cablesglass

used to make light framesfor bicycles

polythene

used to make packaging forelectrical equipment

polystyrene

used to make car windscreensPVC

used to make tables and chairsrubber

used to make compact discssteel (iron)

used to make supermarketcarrier bags

wood




Sharing responses

You have a set of cards. These cards contain the jobs you looked at in Activity H1a, andproducts or other terms associated with these jobs.

There are four ‘job’ cards and sixteen product/term cards.

Play a matching-card game.

1 Shuffle the product/term cards and deal four to each player.

2 Shuffle the job cards and put one card face up on the desk.

3 Each player now takes a turn at matching a product/term card with this job card.

4 If a player has no matching card he says ‘pass’ and the next player has a go.

5 When all four players say ‘pass’ turn the next job card face up on the desk.

6 Continue playing until one player has no cards. He/she is the winner.

Make a note of which cards match each job so that you can report this back to theclass later.

Job cards Product/term cards

ammonia

antibiotic

aspirin

drugs

ethane

explosives

fertilisers

Fritz Haber

hard-wearing

penicillin

plastic

polythene

polymerisation

resistant to water

useful materials

stiff

Machine operator

Pharmacist

Chemical engineer

Materials scientist



Word game

Twelve words to do with this topic are hidden in this wordsearch.

How many can you find?


F E R T I L I S E R

A V A O W I S P J Y

P O L Y T H E N E L

A T U H F U E L M A

C A M M O N I A U S

N D I R O N Y F F P

C X N T D E R V O I

F R I T Z H A B E R

X R U B B E R Z L I

C O M B U S T I O N



H2 PlenariesEnergy from reactions

Review learning� Pupils work individually or in groups to write a definition of the word

‘fuel’. Ask pupils in turn to read out their definitions to the class.

� Write a final class definition, agreed by the class, on the board. ‘Asubstance that is burned to provide a source of energy’.

Sharing responses� Pupils report their results from Activity H2a to the rest of the class. Ask

pupils to describe their observations and answers to the questions.

� Discuss these with the class, and summarise them on the board.

Group feedback� Pupils work in their groups from Activity H2b, using the questions and

discussion from the activity to produce an advertising poster for a fuel.

� Tell pupils that the poster must appeal to those who might purchase thefuel, and encourage them to purchase this fuel.

Word game� Pupils work in groups, using a set of cards to help them construct word

equations for the reactions that took place in Activity H2a.

� Ask them to construct a word equation for the first reaction in ActivityH2a, between iron filings and copper sulphate solution.

� Ask one group to tell the rest of the class the equation they haveconstructed.

� Write this equation on the board. Continue with the other equations.

Looking ahead� Pupils watch a demonstration in which barium nitrate solution is added

to sodium sulphate solution.

� In a boiling tube half filled with sodium sulphate solution, add fewdrops of barium nitrate. Filter out the resulting white precipitate fromthe solution. Then add more barium nitrate to the clear filtrate. Repeatthis at least two more times. The precipitate is barium sulphate.

� Ask pupils ‘Could we go on doing this forever?’

� Elicit the idea that eventually all of the sulphate in the solution willhave been removed as barium sulphate, so no further reaction will takeplace when more barium nitrate is added.

➔ Pupil sheet

Answers1 iron + copper sulphate →

copper + iron sulphate2 magnesium +

copper sulphate →copper + magnesiumsulphate

3 zinc + copper sulphate →copper + zinc sulphate

Equipment1.0 mol/dm3 barium nitrate solution;1.0 mol/dm3 sodiumsulphate solution;four boiling tubes; stand forboiling tubes; three filterfunnels, each with filterpaper; dropping pipette


Review learning

Pupils write a definitionof the word ‘fuel’.Individuals read out theirdefinitions to the class.

Sharing responses

Pupils report results ofActivity H2a to the class.Results are summarisedon the board anddiscussed.

Group feedback

Pupils work in groups usinginformation from Activity H2b toproduce an advertising poster for afuel, designed to appeal to thosewho might purchase the fuel.

Word game

Pupils use cardsto constructword equationsfor the reactionsin Activity H2a.

Looking ahead

Demo adding barium nitrate solutiona little at a time to sodium sulphatesolution, each time getting moreprecipitate. Ask pupils ‘Could we goon doing this forever?’


H2 PlenariesEnergy from reactions

Word game

In Activity H2a three chemical reactions took place.

The first was when you added iron filings to copper sulphate solution.

1 Look back and see what happened in this reaction.

2 Use the cards to construct a word equation for the reaction.

3 Your teacher may ask you to tell the rest of the class what you have done, and willwrite the correct equation on the board.

4 When instructed by your teacher, use the cards to construct word equations for theother two reactions that took place in Activity H2a.


iron

magnesium

zinc

copper

sulphate

+

+

→



H3 PlenariesReactions in balance

Review learningUse the Teacher sheet to direct the role play.

Sharing responses� Ask groups in turn to report to the rest of the class their results from Activity H3a.

� Discuss these results with the class, and ask for explanations.

� Lead the discussion to ideas that chemical reactions do not involve an overall changein mass. Instead they involve ‘re-arrangement’ of atoms to form different compounds.

� Mention the idea of ‘conservation of mass’ during chemical reactions.

Group feedback� Ask groups in turn to report to the rest of the class their results from Activity H3a.

� Ask pupils if these results contradict the idea of conservation of mass duringchemical reactions.

� Explain, or get pupils to explain, that the total mass is the same since the massgained by the magnesium has been lost from the air.

� Choose a good set of results, or present a ‘perfect’ set of results to show that each 24 g of magnesium reacts with 16 g of oxygen.

� For more able pupils relate these masses to the relative atomic masses of magnesiumand oxygen, showing that the atoms have joined in a 1:1 ratio.

� Use this idea to write a symbol equation for the reaction.

� Ask pupils to suggest why their results are not the same as the perfect resultsexpected from the equation.

� Lead pupils to the idea that not all magnesium is burning and/or there is loss ofmagnesium oxide as ‘smoke’ when the crucible lid is lifted.

Word game� Pupils play Taboo using cards cut out from the pupil sheet.

� Give one pupil a card with a mystery word on it. The pupil offers clues to the classto allow them to identify the mystery word, but is not allowed to use the given‘taboo’ words in their clues.

� You can adjust the level of challenge by banning the use of just the first, or first andsecond words in the taboo list, and then increase the number later.

Looking back� Pupils revise and consolidate work from the unit. They can use the Unit map, Pupil

checklist, or the Test yourself questions.

➔ Teacher sheet

➔ Pupil sheet

➔ Unit map

➔ Pupil checklist

➔ Test yourself


Review learning

Role play of magnesiumburning, with pupilsacting as magnesiumatoms and oxygenmolecules.

Sharing responses

Groups report their resultsfrom Activity H3a to theclass. Discussion leads toideas of conservation ofmass.

Group feedback

Groups report their results fromActivity H3b. A ‘perfect’ set ofresults is used to write asymbol equation. Pupilssuggest why their results donot fit the equation exactly.

Word game

Pupils work in groups toplay game of ‘Taboo’using words relevant tothese activities.

Looking back

Pupils revise and consolidateknowledge from the unit.




Review learningTeacher sheet� Divide the class in half. Ask half of the pupils to stand in a group. These

pupils are modelling magnesium molecules. Ask the other half to stand inpairs holding hands, in random arrangement around the first group. Thesepupils are modelling oxygen molecules.

� Tell pupils that when you say ‘go’, the oxygen molecules are to movearound randomly. When they meet the magnesium atoms they let go ofeach other and each holds hands with a magnesium atom to formmagnesium oxide. Each magnesium oxide pair then moves a little to allowoxygen to get to the magnesium in the middle of the group.

� Tell pupils that when you say ‘stop’ they must stop moving.

� Stop pupils at stages during the ‘reaction’ so that you can point out to themthe way that magnesium on the outside burns first, and that it takes time forall of the magnesium to be burned.

� Point out that the magnesium oxide formed will be heavier than themagnesium (more pupils).

� The modelling can be extended to include the effect of raising the cruciblelid during the reaction. To do this, ask some of the pupils who are modellingoxygen molecules to stand in a corner away from the magnesium atoms.When all, or nearly all, of the other oxygen molecules have reacted, say‘raise the lid’ at which time the oxygen molecules move from the corner tothe magnesium for the reaction to continue.




Word game

Combustion

� burning� heat� oxygen

TabooAtom

� element� molecule� particle

Taboo

Reaction

� reactant� product� chemical

TabooMolecule

� atom� element� particle

Taboo

Reactant

� reaction� product� chemical

TabooMass

� weight� measurement� amount

Taboo

Product

� reaction� reactant� chemical

TabooEquation

� symbol� word� reactant� product

Taboo



H4 PlenariesThe story of burning – Think about

Group feedback� Ask each group in turn to report to the class their

observations from Activity H4a.

� Ask pupils to compare the ideas that they have gainedfrom the activity with the ideas of Priestley andLavoisier.

� Give each group a few minutes to discuss thiscomparison.

� Ask each group in turn to present their comparison tothe class.

� Ask pupils whether the evidence from Activity H4aconfirms or changes the ideas of Priestley and Lavoisier.

� Ask pupils whether the ideas of Priestley and Lavoisierconfirmed or changed the ideas of most scientists atthat time.

Bridging to other topics� Show pupils a video and/or photographs of a space

rocket taking off.

� Tell pupils that the fuel used by these rockets is the gashydrogen. Tell them that hydrogen has a boiling pointof –253 ºC. Tell pupils that there is no oxygen in space.

� Ask pupils to discuss in groups the two questionsopposite.

� Ask each group in turn to give their ideas to the rest ofthe class.

� Discuss pupils’ ideas with the class to arrive at ideas ofstorage of hydrogen at low temperatures under pressure,and similar storage of oxygen (boiling point –183ºC), inthe rockets.

� Ideas can be extended to the use of re-usable boostertanks for the space shuttle.

➔ Catalyst Interactive Presentations 3

Questions1 How is this hydrogen stored in rockets?

2 Where does the oxygen needed to burnthe fuel come from?


Group feedback

Groups report their results from Activity H4a to theclass for discussion. They then compare what theyhave learned from practical evidence with the ideasof Priestley and Lavoisier. They see that evidencehelps to confirm or change people’s ideas.

Bridging to other topics

Show video or photos of space rockets taking off.Explain that the fuel is the gas hydrogen, and askpupils to suggest how it is stored in the rocket andwhere the oxygen for burning comes from. Catalyst Interactive Presentations 3


H1 SpecialsProducts from reactions

1 Use some of these words to fill in the gaps.

a Chemical reactions make materials frommaterials.

b Some chemical reactions, such as food, are useful.Some, like food going , are not useful.

c Chemical reactions go on inside all things. Plantsuse chemical reactions to make the they need.Humans use chemical reactions to get from food.

2 Look at the list below. There are some raw materials and the newmaterials that can be made from them. They’re all muddled up. Drawlines to match the raw material to the new material it can make.


ironbad tasty new living food

energycooking burning raw oil

oil glass

fungus

brick

sand papersteel

Quorncement

cement

clay

iron ore

limestone

plasticwood

Distance Leewalked = 50 mTime Lee tookto walk it

= 25 s

Raw materials New materials

H-Specials.qxd 08-Jun-04 3:03 PM Page 1

H2 SpecialsEnergy from reactions

1 Use a tick (�) to show the correct answers.

a Fuels are a store of:

electrical energy

chemical energy

heat energy

b The reaction that releases energy from fuels is called:

competition

completion

combustion

c When a fuel burns, the gas from the air that reacts with it is called:

nitrogen

oxygen

carbon dioxide

d Two types of energy are released when a fuel burns. They are called:

kinetic (movement)

heat

chemical

electrical

light



H2 SpecialsEnergy from reactions (continued)

2 Use words from this list to fill in the gaps. You may need to use thewords once, more than once or not at all.

a When coal burns, is released.

b When a hydrocarbon burns, andare made.

c The three fossil fuels are , and.

d Natural gas contains a substance called .

e In Brazil, people run their cars on , which is madefrom .

f When hydrogen burns, is made.

3 Look at this diagram showing the combustion of coal.

a The reactants are and .

b The products are , and.

c The word equation for the reaction is:

coal + + water +


watersugar oil oxygen

carbon dioxide

natural gas

ethanol

methane

wood coal energy

energyreleased


H3 SpecialsReactions in balance

1 Look at these pictures. They show what happens to the atoms wheniron and sulphur react.

a How many iron atoms are there in the iron?

b How many sulphur atoms are there in the sulphur?

c How many iron atoms are there in the iron sulphide?

d How many sulphur atoms are there in the iron sulphide?

e Do the number of iron and sulphur atoms change during thechemical reaction?

f Write a word equation for this reaction.iron + →

2 Write true or false for each sentence.

a In a chemical reaction the mass of the chemicalsyou start with is the same as the mass of the chemicalsyou make.

b ‘Mass is conserved’ is another way of saying the masschanges.

c The number of atoms involved in a chemical reactiondoesn’t change.

d The atoms are rearranged in a chemical reaction tomake the new chemicals.


+s s ss s ss s s

ss

ss

ss

sss

heat

iron sulphur iron sulphide


H3 SpecialsReactions in balance (continued)

3 When iron and sulphur are heated together, they make a newchemical called iron sulphide.

Look carefully at the pictures. Use the information to answer thequestions below them.

a What is the mass of iron? g

b What is the mass of sulphur? g

c What is the total mass of iron + sulphur?mass of iron + sulphur = g + g

= g

d What is the mass of the iron sulphide? g

e Underline the correct phrase to complete the sentence.The total mass of iron and sulphur is bigger than/the same as/smaller than the mass of the iron sulphide.

f 10.8 g of iron react with 6.4 g of sulphur to make iron sulphide.What will the mass of the iron sulphide be?mass of iron + mass of sulphur = g + g

= g


iron +sulphur

iron sulphide

ironsulphur1 2

3 4


H4 SpecialsThe story of burning

1 Draw lines to match the scientist to the idea he had about burning!


He believed that when thingsburn, they split apart andrelease phlogiston.

He heated red calx up.Mercury was made. A gaswas also made.

He showed that a gas in the airwas involved in burning. Hecalled this gas oxygen.

George Stahl1703

Joseph Priestley1774

Antoine Lavoisier1775

2 Look at these pictures.Use a tick (�) to showthe correct answers.

a The mass of themagnesium has:gone down stayed the same gone up.

b The mass has changed because:the magnesium has lost phlogistonthe magnesium has lost oxygenthe magnesium has combined with oxygen.

c This experiment supports the belief of:Stahl Priestley Lavoisier.

1

weigh magnesium weigh ashburn and collect ash

2 3


H Specials answersUsing chemistry

H1 Products from reactions1 a new, raw

b cooking, badc living, food, energy

2 oil – plasticiron ore – steelsand – glassfungus – Quornclay – bricklimestone – cementwood – paper

H2 Energy from reactions1 a chemical energy

b combustionc oxygend heat, light

2 a energyb water, carbon dioxidec coal, oil, gasd methanee ethanol, sugarf water

3 a coal, oxygenb carbon dioxide, water, soot

c coal + oxygen carbon dioxide+ water + soot

H3 Reactions in balance1 a 9

b 9c 9d 9e nof iron + sulphur → iron sulphide

2 a trueb falsec trued true

3 a 5.4b 3.2c 5.4, 3.2, 8.6d 8.6e the same asf 10.8, 6.4, 17.2

H4 The story of burning1 George Stahl – He came up with the idea of

phlogiston to explain burning. When thingsburn, they split apart and release phlogiston.Joseph Priestley – He heated red calx up.Mercury was made. A gas was also made.Antoine Lavoisier – He showed that a gas in theair was involved in burning. He called this gasoxygen.

2 a gone upb the magnesium has combined with oxygenc Lavoisier


energyreleased

Spe Answers.qxd 6/23/2004 9:19 AM Page 8

H1 HomeworkProducts from reactions


HELP

1 Choose from the list below to answer the following questions.

a Louise’s great granny is telling her about what things weremade of when she was a girl in 1920. Choose a material thateach thing might be made from today.

i A bath sponge.

ii Tyre round a car wheel.

iii Rope to lower a bucket into a well.

iv A car bumper.

v An oven dish.

b The items in the list above are made from raw materials.Which material is made from:

i Sand.

ii Crude oil.

iii The sap of a tropical tree.

CORE

2 For each of the changes described below, say whether they arehelpful or harmful to us and explain your reasons.

a Bacteria growing on meat that is past its sell-by date.

b Carbon dioxide combining with water in a plant.

c Carbon combining with oxygen on a barbecue.

d Glucose being converted into carbon dioxide and water.

3 The raw material copper oxide can be heated with carbon toproduce pure copper, to use for electrical wires.

a What product is formed, other than copper?

b Write a word equation to represent the reaction.

plastic nylonrubber Pyrex glass foam

H-Homework.qxd 26-May-04 1:16 PM Page 1

H1 HomeworkProducts from reactions (continued)

EXTENSION

4 Aluminium is obtained from aluminium oxide by the reactiongiven below.

aluminium oxide aluminium + oxygen

Electricity is used to split the aluminium away from the oxygen.

a Explain why aluminium is relatively expensive, compared withcopper.

b Thinking back to your work on burning fuels, suggest areason why extracting aluminium in this way adds to thegreenhouse effect.

5 a Explain how fermentation is

i similar to respiration.

ii different from respiration.

b Write the word equation for respiration.



H2 HomeworkEnergy from reactions

HELP

1 Jane is looking at the flame of her Bunsen burner.

a Write down two things she observes that show a chemical change is happening.

b Give the name of the gas that is burning.

c Copy and complete the following sentences:

i The gas in a Bunsen burner is a fossil fuel because .

ii When the gas burns it is combining with .

iii When the gas burns it produces .

iv The type of energy stored in the gas is called .

CORE

2 The table gives some information about a range of fuels.

a Which fuel is useful to countries with small fossil fuel reserves?

b Which fuel could not be used easily for powering cars?

c i Which of the fuels would be the most polluting?

ii Explain the reason for your choice.

d i Write a word equation to represent the reaction that takes place when the carbon in coal burns in air.

ii Explain how the products from this reaction are different from those formed when ethanol burns in air.

3 Sam’s house has no gas supply. Everything works by electricity. Explain why Sam’s house still contributes to global warming.


Fuel State at room Other informationtemperature

Hydrogen Gas Very low density. Explosive when mixed with air.

Coal Solid Contains mostly carbon with some sulphur.Hard to ignite.

Ethanol Liquid Made from sugar. Ignites easily.


H2 HomeworkEnergy from reactions (continued)

EXTENSION

4 When methane burns in plenty of air carbon dioxide and water are formed.

a Explain why methane is often called a hydrocarbon.

b Write down the word equation for the reaction when methane burns in plenty of air.

c i What would be different about the reaction if the air supply was very restricted?

ii Write the word equation for methane burning in a limited air supply.

iii Why would this be a problem in a caravan heated by a gas heater, if the air vent was blocked.

d Explain why natural gas is a non-renewable energy source but ethanol is a renewable energy source.



H3 HomeworkReactions in balance

HELP

1 Farina mixes together 2 g of hydrogen and 16 g of oxygen in a specialsteel container. She ignites the mixture so that the two gases react. Shehas used just the right amounts of each gas to make them react exactly,with none left over. She finds the mass of the products.

a What new compound will Farina make?

b What mass of the new compound will she collect?

c In a chemical reaction the mass is always conserved. Say how Farina’sexperiment shows that this is true.

d In Farina’s experiment two atoms of hydrogen join with one atom ofoxygen. How many atoms are there in the product from the reaction?

2 In another experiment, Joel strongly heats some zinc in a clay pot. The zinc reacts with oxygen in the air.

a Will the mass of material in the pot go up, go down or stay the same?

b Explain your reasoning.

c If 8 g of zinc reacts with 2 g of oxygen, what mass of product will Joel make?

CORE

3 Look at the results below, from Susie’s experiment. She has heated somemagnesium ribbon in a crucible.

Mass of crucible alone = 10.5 gMass of crucible + magnesium ribbon = 11.7 gMass of crucible and contents after heating = 13.3 g

a Calculate the mass of magnesium that Susie burned.

b Calculate the mass of oxygen that reacted with the magnesium.

c Calculate the mass of magnesium oxide that formed in the crucible.

d Explain how the idea of conservation of mass is shown by Susie’s experiment.



H3 HomeworkReactions in balance (continued)

e Susie did another experiment to check her results. She noticed that,this time, a stream of white smoke came up from the crucible as themagnesium was burning.

i How would this problem affect the mass of the crucible andcontents after heating?

ii In what way would this experiment suggest that the idea ofconservation of mass is wrong.

iii What could Susie do, in a third experiment, to try to solve theproblem?

f Write a word equation to represent the reaction in Susie’sexperiments.

g What is true about the number of atoms on each side of the equationyou have written?

EXTENSION

4 a The balanced equation for sulphuric acid reacting with sodiumhydroxide is:

H2SO4 + 2NaOH Na2SO4 + 2H2O

How many atoms are there

i on the left of the equation?

ii on the right of the equation?

iii Explain how this confirms the idea of conservation of mass.

b Copy and complete the symbol equation for the extraction ofaluminium, which is shown unbalanced below.

Al2O3 4Al + O2

c Use the formulae shown below to write the balanced equation forthe reaction between hydrochloric acid and potassium hydroxide,forming potassium chloride and water.


H22O KOHHCI KCI


H1Homework

mark schemeProducts from reactions


HELPQuestion Answer Mark

1 a i Foam 1

ii Rubber 1

iii Nylon 1

iv Plastic 1

v Pyrex glass. 1

b i Pyrex glass. 1

ii Plastic, nylon and foam. 1

iii Rubber 1

Total for Help 8

COREQuestion Answer Mark

2 a Harmful 1because it forms poisonous chemicals that would make us ill. 1

b Helpful 1because it is photosynthesis/it makes glucose/it is the only waythat the Sun’s energy can be converted into chemical energy. 1

c Helpful 1because it produces heat to cook the food. 1

d Helpful 1because it provides energy from the food we eat. 1

3 a Carbon dioxide 1

b copper oxide + carbon copper + carbon dioxide 1

Total for Core 10

EXTENSIONQuestion Answer Mark

4 a Electricity is expensive. 1

b Fuels are burned to generate electricity. 1Burning fuels to make electricity produces carbon dioxide. 1Carbon dioxide is the main greenhouse gas. 1Accept alternative equivalent responses.

5 a Both produce carbon dioxide. 1

b Respiration produces water but fermentation produces ethanol/alcohol. 1

c glucose + oxygen carbon dioxide + water 2Award 1 mark for the reactants and 1 mark for the products

Total for Extension 8


H2Homework

mark schemeEnergy from reactions



1 a Heat and light. 2

b Methane 1

c i The gas in a Bunsen burner is a fossil fuel because it was made fromthe remains of dead animals millions of years ago. 1Accept equivalent response. Underscore shows the pupil’s answer.

ii When the gas burns it is combining with oxygen. 1

iii When the gas burns it forms carbon dioxide and water. 2Award one mark for each product.

iv The type of energy stored in the gas is called chemical energy. 1

Total for Help 8


2 a Ethanol 1

b Coal 1

c i Coal 1

ii It contains sulphur 1which burns to form sulphur dioxide 1which causes acid rain/breathing difficulties. 1

d i carbon + oxygen carbon dioxide 1

ii Ethanol also forms water. 1

3 Electricity is usually made by burning fossil fuels 1which produces carbon dioxide that increases global warming. 1

Total for Core 10


4 a It contains only carbon and hydrogen. 1

b methane + oxygen carbon dioxide + water 1

c i Carbon monoxide would be produced instead of carbon dioxide. 1

ii methane + oxygen carbon monoxide + water 1

iii The blocked vent restricts the air supply to the flame 1so carbon monoxide is produced 1and carbon monoxide is poisonous. 1

d Natural gas is not replaced as it is used but ethanol is made fromsugar cane, which can be quickly replaced. 1Do not give any marks for answers that refer to ideas about re-use of the fuel.



H3Homework

mark schemeReactions in balance



1 a Water 1

b 18 g 1

c She started with 18 g of hydrogen and oxygen mixed together 1and finished with 18 g of water. 1Accept equivalent responses.

d 3 1

2 a It will go up. 1

b The zinc will combine with oxygen adding to the mass. 1

c 10 g 1

Total for Help 8


3 a 1.2 g 1

b 1.6 g 1

c 2.8 g 1

d The mass of the reactants added together 1is the same as the mass of the product. 1

e i It would reduce it. 1

ii The mass of product would now be less than the total massof the reactants. 1

iii She could put a lid on the crucible. 1

f magnesium + oxygen magnesium oxide 1

g It will be the same. 1

Total for Core 10


4 a i 13 1

ii 13 1

iii The same number of atoms must have the same mass 1so the mass is the same on both sides of the equation. 1

b i Balanced equation is: 2Al2O3 4Al + 3O2 2Award 1 mark for each underlined balancing number.

c Balanced equation is: HCl + NaOH NaCl + H2O 2Award 1 mark for correct reactants and products and 1 markfor correct balancing.



H Test yourselfUsing chemistry

1 Reactions can be classified as three types:

A reactions used to provide energy

B reactions used to make new materials

C important reactions in biological systems

Are the following examples of A, B or C ?

a Limestone is roasted with clay to make cement.

b Glucose is oxidised in cells to produce carbon dioxide. ,

c Waste straw is burned in a power station.

2 Tick the useful reactions, and put a cross by the ones that are not useful.

photosynthesis rotting food

corrosion combustion

respiration digestion

3 a Rearrange the letters to make another name for burning.

NO BUS IT COM

b Rearrange the letters to write the name of what is released when a fuel burns.

GREENY

4 Underline two hydrocarbons in the list.

air hydrogen

candle wax petrol

5 Complete the following sentences. Use the words below to fill the gaps.

When natural gas burns, it joins with gas from the air and

releases . If there is plenty of air, carbon

and are formed.


dioxide energy monoxide oxygen soot water

Test-Qust.qxd 6/25/2004 10:32 AM Page 22

H Test yourselfUsing chemistry (continued)

6 Tim and Sue are choosing a good fuel for the open fire in the living room.

Choose three properties of a good fuel.

A burns with a yellow, sooty flame

B gives out a lot of energy

C burns very quickly

D catches alight easily

E is not expensive

The three properties are:

7 The list gives four metals in order of decreasing reactivity.

Tin is added to lead nitrate. Complete the word equation.

tin + lead nitrate → nitrate +

8 Diagram A shows a mixture of hydrogen and oxygen. Diagram Bshows how the atoms are rearranged in a reaction to produce water.

Complete diagram B to show the correct number of water molecules.

9 For each of these statements underline the right word, true or false.

a There is always a change in mass when a chemical reaction takes place. true/false

b Energy is always given out when a chemical reaction takes place. true/false

c If 10 g of salt are dissolved in 100 g of water, the solution weighs 110 g. true/false

d If a piece of wood is burned and all the products are collected, the sum of the masses of the products is the same as the mass of the piece of wood. true/false


magnesium

zinc

tin

lead

A

Key

hydrogen

water

oxygen

B

Test-Qust.qxd 6/25/2004 10:32 AM Page 23

HTest yourself

AnswersUsing chemistry

1 Reactions can be classified as three types:

A reactions used to provide energy

B reactions used to make new materials

C important reactions in biological systems

Are the following examples of A, B or C ?

a Limestone is roasted with clay to make cement.

b Glucose is oxidised in cells to produce carbon dioxide. ,

c Waste straw is burned in a power station.

2 Tick the useful reactions, and put a cross by the ones that are not useful.

photosynthesis rotting food

corrosion combustion

respiration digestion

3 a Rearrange the letters to make another name for burning.

NO BUS IT COM

b Rearrange the letters to write the name of what is released when a fuel burns.

GREENY

4 Underline two hydrocarbons in the list.

air hydrogen

candle wax petrol

5 Complete the following sentences. Use the words below to fill the gaps.

When natural gas burns, it joins with gas from the air and

releases . If there is plenty of air, carbon

and are formed.water

dioxideenergy

oxygen

ENERGY

COMBUSTION

��

�✗

✗�

A

CB

B


dioxide energy monoxide oxygen soot water

Test-Ans.qxd 16-Jun-04 2:55 PM Page 22

HTest yourself

AnswersUsing chemistry (continued)

6 Tim and Sue are choosing a good fuel for the open fire in the living room.

Choose three properties of a good fuel.

A burns with a yellow, sooty flame

B gives out a lot of energy

C burns very quickly

D catches alight easily

E is not expensive

The three properties are:

7 The list gives four metals in order of decreasing reactivity.

Tin is added to lead nitrate. Complete the word equation.

tin + lead nitrate → nitrate +

8 Diagram A shows a mixture of hydrogen and oxygen. Diagram Bshows how the atoms are rearranged in a reaction to produce water.

Complete diagram B to show the correct number of water molecules.

9 For each of these statements underline the right word, true or false.

a There is always a change in mass when a chemical reaction takes place. true/false

b Energy is always given out when a chemical reaction takes place. true/false

c If 10 g of salt are dissolved in 100 g of water, the solution weighs 110 g. true/false

d If a piece of wood is burned and all the products are collected, the sum of the masses of the products is the same as the mass of the piece of wood. true/false

leadtin

EDB


magnesium

zinc

tin

lead

A

Key

hydrogen

water

oxygen

B

Test-Ans.qxd 16-Jun-04 2:55 PM Page 23

HEnd of unit test

GreenUsing chemistry

1 Petrol is a fuel.

a Write down the two words from the list below that best describe petrol. 2 marks

b What substance is needed for petrol to burn? 1 mark

c What is given out when a fuel burns, that makes a fuel useful? 1 mark

d Write a word equation for the burning of methane in oxygen. 2 marks

e Hydrogen can be used as a fuel in motor vehicles in place of petrol. It burns in air to produce water.

Write down one advantage of using hydrogen as a fuel, compared with using petrol or diesel. 1 mark

2 a Sam dissolves 10 g of sodium chloride crystals in 100 g of water. What is the mass of the resulting solution? Write down the letter.

A 100 g B 10 g C 110 g D 90 g 1 mark

b Sam reads that the total mass of reactants is always the same as the total mass of products. When 0.24 g of magnesium reacts with 0.16 g of oxygen, what mass of magnesium oxide would Sam expect to get? Write down the letter.

A 0.24 g B 0.40 g C 0.16 g D 0.08 g 1 mark

c Write down the letter for the correct answer. When a chemical reaction takes place, the total number of atoms in the reactant is: 1 mark

A always different from the number of atoms in the productB sometimes different from the number of atoms in the productC always the same as the number of atoms in the productD sometimes the same as the number of atoms in the product.

d Describe how the atoms in the reaction below have been arranged in the reaction. 1 mark


element hydrocarbon liquid solution

sulphur sulphur dioxideoxygen+

G-I-EUTest.qxd 18-Jun-04 10:47 AM Page 7

HEnd of unit test

GreenUsing chemistry (continued)

e The equation below shows the reaction between hydrogen and oxygen to produce water.

i How many hydrogen atoms are there on each side of the equation? 1 markii How many oxygen atoms are there on each side of the equation? 1 markiii How does the number of atoms in the equation show that mass

is conserved in the chemical reaction? 1 mark

3 Carbon burns in oxygen to form carbon dioxide (CO2).

a Copy and complete the diagram showing the changed arrangement of particles when this reaction takes place. 2 marks

b What is released, in addition to carbon dioxide, when carbon is burned 1 mark

4 Copper reacts with silver nitrate solution and produces silver.

a Write down the best word from the list below to describe this reaction. 1 mark

b Copy and complete this word equation. 1 mark

copper + silver nitrate →→ silver +

c The beaker becomes warm during this reaction. Why is this? 1 mark


hydrogen wateroxygen+

key

carbon atom

oxygen atom

combustion displacement neutralisation


HEnd of unit test

GreenUsing chemistry (continued)

5 A new source of protein calledmycoprotein has been developed forhuman food. It is made by growinga fungus on glucose derived frommaize starch. The harvestedmycoprotein is made to look andtaste like meat and is marketedunder the brand name Quorn.

This is the nutrition informationtable for mycoprotein:

a How many grams of protein are there in 100 grams of mycoprotein? 1 mark

It took fifteen years of research to develop the product Quorn.This included ten years of testing before it was approved for human consumption.

b i Suggest a reason why new products are tested thoroughly before being approved for human use. 1 mark

The results of scientific testing are usually published so that other scientists can look at them. They can then try to produce the same results.

ii Suggest why it is important that other scientists try to produce the same results of an experiment. 1 mark

When an ingredient like mycoprotein is being developed, scientists use small-scale experiments using laboratory-size flasks. When they are sure everything is working properly, a full-size production factory is built.

c i Why do scientists think it is important to carry out small-scale experiments before building full-scale factories? 1 mark

This table shows the nutritional information for a typical fast-food cheeseburger.

ii How does the amount ofdietary fibre in 100 g ofmycoprotein compare with that in 100 g ofcheeseburger? 1 mark


Constituent Mass (g per 100 g)

Protein 12.0

Dietary fibre 6.0

Fat 3.0

Carbohydrate 3.0

Sodium 0.005

Cholesterol 0.0

Water 75.0


Protein 15.6

Dietary fibre 1.5

Fat 13.4

Carbohydrate 30.0

G-I-EUTest.qxd 22-Jul-04 9:33 PM Page 9

HEnd of unit test

RedUsing chemistry

1 The diagram shows a gas burner.

a Write a word equation for the burning of methane in oxygen. 2 marks

b Hydrogen can be used as a fuel in motor vehicles in place of petrol. It burns in air to produce water.

Write down one advantage of using hydrogen as a fuel, compared with using petrol or diesel. 1 mark

2 Carbon burns in oxygen to form carbon dioxide (CO2).

a Copy and complete the diagram showing the changed arrangement of particles when this reaction takes place. 2 marks

b What is released, in addition to carbon dioxide, when carbon is burned? 1 mark

c The diagram shows how nitrogen and hydrogen can react to form ammonia.

How does the diagram show that the mass of the reactants and products is the same? 1 mark

d When copper carbonate is heated, carbon dioxide gas is given off and black copper oxide is left.

i Why is the mass of copper oxide left less than the mass of copper carbonate that was heated? 1 mark

ii Copy and complete the symbol equation for the reaction. 1 mark

CuCO3 →→ +


gas burner

small blueflames

key

carbon atom

oxygen atom

key

nitrogen atom

hydrogen atom


HEnd of unit test

RedUsing chemistry (continued)

e The equation below shows the reaction between hydrogen and oxygen to produce water.

How does the number of atoms in the equation show that mass is conserved in the chemical reaction? 1 mark

3 Copper, zinc and magnesium are added to separate samples of silver nitrate solution.

a Copy and complete the word equation. 2 marks

copper + silver nitrate →→ +

b Here is a list of four metals in decreasing order or reactivity:magnesiumzinccoppersilverJenny carries out the following reaction:

A magnesium with silver nitrate solutionB copper with silver nitrate solutionC zinc with silver nitrate solution.

i Which combination of metals shown above will release the most energy, A, B or C? 1 mark

ii Which combination of metals shown above will release the least energy, A, B or C? 1 mark

4 The diagram shows apparatus that can be used to turn copper oxide into copper. Water is also produced.

a Write a symbol equation for the reaction? 2 marks

b Explain why the mass of the test tube and contents decreasesduring the reaction. 2 marks


hydrogen wateroxygen+

heat

copper oxide

hydrogen

excess hydrogenburning


HEnd of unit test


Groups of students did thisexperiment with different masses of copper oxide. Here is a graphshowing their results.

c Use the graph to find the mass of copper oxide needed to produce 0.50 g of copper. 1 mark

d Copper can be converted into copper oxide.

What mass of copper oxide would be produced from 0.64 g of copper? 1 mark

5 A new source of protein called mycoprotein has been developed for human food. It ismade by growing a fungus on glucose derived from maize starch. The harvestedmycoprotein is made to look and taste like meat and is marketed under the brandname Quorn.

This is the nutrition information table for mycoprotein:

When an ingredient likemycoprotein is being developed,scientists use small-scale experiments using laboratory-sizeflasks. When they are sure everything is working properly, a full-size production factory is built.

a Why do scientists think it is important to carry out small-scale experiments before building full scale factories? 1 mark

This table shows the nutritionalinformation for a typical fast-foodcheeseburger:

b i How does the amount ofdietary fibre in 100 g of mycoprotein compare withthat in 100 g of cheeseburger? 1 mark


0.2 0.4 0.6 0.8 1.00Mass of copper oxide (g)

Mas

s of

cop

per

(g)

0

0.2

0.4

0.6

0.8


Protein 12.0

Dietary fibre 6.0

Fat 3.0

Carbohydrate 3.0

Sodium 0.005

Cholesterol 0.0

Water 75.0


Protein 15.6

Dietary fibre 1.5

Fat 13.4

Carbohydrate 30.0


HEnd of unit test


Many doctors are very concerned that we have a diet that is too high in carbohydrate and fat.

ii Use the nutritional information tables to suggest how eating foods made with mycoprotein might help to improve our diet. 1 mark

Mycoprotein was developed because in the 1950s scientists predicted a world-wide shortage of high protein foods. High protein foods are usually meat or fish which are expensive to produce and the animals take many months to grow before they can be used for meat.

Mycoprotein in Quorn is made by growing a fungus on glucose derived from maize starch. Once harvested, it can be made to look and taste like meat. The process takes several weeks.

c Suggest two reasons why scientists think that mycoprotein may be an answer to a shortage of protein rich foods for humans. 2 marks




HEnd of unit test

mark schemeUsing chemistry

Green (NC Tier 3–6)Question Answer Mark Level

1 a Hydrocarbon 1 3Liquid 1 3

b Oxygen or air. 1 4

c Energy or heat or light. 1 4

d Methane + oxygen → carbon dioxide + water One mark for left-hand side, one mark for right-hand side. 2 6

e It produces no pollution or named pollutant. 1 6

2 a C 1 5

b B 1 5

c C 1 4

d Oxygen has combined or joined with sulphur or 1 5sulphur dioxide molecules have been formed.

e i 4 hydrogen atoms on each side. 1 4ii 2 oxygen atoms on each side. 1 4iii There are the same number of atoms on each side of the equation. 1 6

3 a Diagram shows:Molecules with one carbon joined to two oxygen atoms. 1 5The same number of carbon and oxygen atoms on each side. 1 5

b Energy or heat or light. 1 5

4 a Displacement 1 4

b Copper + silver nitrate → silver + copper nitrate One mark for copper nitrate. 1 6

c The reaction gives out energy. 1 5

5 a 12.0 1 4

b i To make sure that there is nothing that could make humans ill. 1 5ii To make sure the results are reliable. 1 5

c i To make sure everything works properly or it would be veryexpensive to build a factory and then find it did not work. 1 6

ii Four times as much dietary fibre or more fibre in mycoproteinthan a cheeseburger. 1 6

Scores in the range of: NC Level

4–6 3

7–11 4

12–16 5

17–25 6



HEnd of unit test

mark schemeUsing chemistry

Question Answer Mark Level

1 a Methane + oxygen → carbon dioxide + water One mark for left-hand side, one mark for right-hand side. 2 6

b It produces no pollution or named pollutant. 1 6

2 a Diagram shows:Molecules with one carbon joined to two oxygen atoms. 1 5The same number of carbon and oxygen atoms on each side. 1 5

b Energy or heat or light 1 5

c The same number of atoms (of each element) in each box. 1 5

d i Because carbon dioxide has been given off. 1 5ii CuCO3 → CuO + CO2

One mark for both products 1 7

e There are the same number of atoms on each side of the equation. 1 6

3 a Copper + silver nitrate → silver + copper nitrate One mark for each product. 2 6

b i A 1 7ii B 1 7

4 a CuO + H2 → Cu + H2OOne mark for left-hand side, one mark for right-hand side. 2 7*

b Copper oxide loses oxygen. 1 7Water is lost from the text tube. 1 7

c 0.64 g (accept 0.63 or 0.65 g). 1 7

d 0.80 g or 0.82 g. 1 6

5 a To make sure everything works properly or it would be very 1 6expensive to build a factory and then find it did not work.

b i Four times as much dietary fibre. 1 6ii Would cut down on carbohydrate by 10 times, and fat by

three quarters. 1 6

c Mycoprotein can be made to look and taste like meat. 1 7Mycoprotein is quicker to produce than meat. 1 7

Scores in the range of: NC Level

5–9 5

10–14 6

15–18 7

19–25 7*

Red (NC Tier 5–7*)


H Pupil checklistUsing chemistry


Learning outcomes I can do I can do I need to this very this quite do more well well work on this

I can describe how products are madefrom raw materials by chemical reactions.

I can name the key stages in the development of a new product.

I can describe some of the jobs carried out by scientists.

I can describe some positive and negative effects of new products.

I can describe how chemical reactions can release energy.

I can identify carbon dioxide and water as the products of burning hydrocarbons.

I can carry out measurements of temperature.

I can identify which fuel is best for which job.

I can describe what happens to atoms in chemical reactions.

I can carry out experiments to show that mass is conserved during chemical reactions.

I can use the Internet to find information about the discovery of oxygen.

Pupil-Checklist.qxd 17-Jun-04 8:00 PM Page 8

H GlossaryUsing chemistry


Word

conserved

hydrocarbon

phlogiston

raw material

voltaic cell R

Definition

The basic material or natural substance from whichsomething is made, such as metal ore.

A simple battery in which electricity passes between twometals placed in dilute acid. R

Stays the same. In all chemical reactions, the mass ofsubstances is conserved.

A substance supposed by eighteenth century scientists to becontained by anything that burns, and that is released byburning.

A substance that contains only carbon and hydrogen atoms.

Glossary.qxd 18-Jun-04 11:33 AM Page 9

H Key wordsUsing chemistry

conserved

hydrocarbon

phlogiston

raw material

voltaic cell R

conserved

hydrocarbon

phlogiston

raw material

voltaic cell R

Sheet 1 of 1

Sheet 1 of 1


Key wordsH Using chemistry


Keywords.qxd 18-Jun-04 11:35 AM Page 8


H Book answersUsing chemistry

H1 Products from reactionsGreena Steel – from iron ore.

Plastic – from chemicals found in oil.Rubber – from the sap of the rubber tree.Glass – from sand.

b i starch → sugar + waterii starch → carbon + water

c vegetariansd From glucose and oxygen.

1 brick – claycement – limestonewallpaper – wood(plaster – gypsum)glass – sand

2 a ironb Carbon dioxide.c iron ore + carbon → iron + carbon dioxide

3 Digestion, respiration, photosynthesis (in anyorder).

Distilcrudeoil.

Get chemicalsfor making

into plastics.

Mould plasticsinto car

accessories.

Manufacture car.

Machineinto engine

blocks.

AluminiumCool, roll into

sheets and pressinto car bodies.

Add small amountof carbon tomolten iron.

Iron oreheated

with coke.

Steel

Wash sandwith acid.

Melt sandwith otherchemicals.

Makeglass

sheets.

Mould intorubber parts

for cars.

Reactwith

sulphur.

Collect sapfrom rubber

trees.

Pass electriccurrent throughmolten bauxite.

b

c Glucose and oxygen.1 Heat the copper oxide with carbon.2 water + carbon dioxide (+ sunlight) → glucose +

oxygen3 a yeast + sugar → ethanol + carbon dioxide

b ethanolc Bread. Flour, fat, water and yeast are heated

to produce bread.4 ammonium hydroxide + phosphoric acid →

ammonium phosphate + water

H2 Energy from reactionsGreena Any three from: wood, paper, cloth, leather,

plastic, or other suitable material.

Extract starchfrom potatoes.

Add fungus tostarch and

allow to grow.

Protein(Quorn)

'Chickennuggets'.

Shapeinto 'nuggets'.

Add chickenflavouring.

b Burning coal produces carbon dioxide. Toomuch carbon dioxide in the atmosphere causesglobal warming.

c Yes. The petrol used in cars comes from oil. Oilwas produced over past centuries by the decay ofanimal matter. All animals require sunlight toproduce their food.

d ethanol + oxygen → carbon dioxide + watere hydrogen + oxygen → waterf There are no other products which would

pollute the atmosphere.1 When petrol burns in a car engine it transfers

energy as ... movement energy and heat energy.Fossil fuels store energy as ... chemical energy.When fuels burn the energy is released as ... heatand some light energy.

2 Carbon and hydrogen.3 a The only product of combustion is water.

b To prevent pollution with carbon dioxide.

Reda Carbon dioxide and water.b Carbon monoxide is produced instead of carbon

dioxide. Carbon monoxide is poisonous.

Reda

Book Answers.qxd 18-Jun-04 12:44 PM Page 21


H Book answersUsing chemistry (continued)

c ethanol + oxygen → carbon dioxide + waterd When hydrogen burns only water is produced.1 Carbon and hydrogen.2 Cleaner burning fuels will cause less pollution.3 Electricity made from oil-fired power stations

will produce carbon dioxide in the process. Solarcells overcome this by producing electricalenergy directly from sunlight.

4 Solar cells placed on the moon could generateelectricity directly from sunlight. This could beused to melt ice deposits and provide water forplants and people.

H3 Reactions in balanceGreena Nathanb The same amounts of substances were there

before and after the reaction. They have justchanged places in making the new compounds.

c Two of hydrogen and one of oxygen. Theformula tells us so.

d Hydrogen, chlorine, sodium and oxygen are onthe left side and on the right side.

1 In a chemical reaction the atoms are rearrangedand combine in a different way. The number ofatoms stays the same in the reaction, so themass is conserved.

2 a iron + oxygen → iron oxideb carbon + iron oxide → carbon dioxide + ironc magnesium + hydrochloric acid → hydrogen

+ magnesium chloride3 a magnesium + oxygen → magnesium oxide

b 1.6 g

Reda Nathanb The same amounts of substances were there

before and after the reaction. They have justchanged places in making the new compounds.

c There are two hydrogen atoms, one oxygenatom, one sodium atom and one chlorine atomon each side of the equation.

1 3.2 g2 a magnesium + oxygen → magnesium oxide

b The magnesium has gained oxygen from theair.

c 1.6 gd 2Mg + O2 → 2MgOe 2.0g. Exactly half of what you got with 2.4 g

of magnesium.3 a calcium carbonate → calcium oxide + carbon

dioxideCaCO3 → CaO + CO2

b yesc Carbon dioxide is lost to the air.

4 a 2Na + Cl2 → 2NaClb 2Na + 2H2O → 2NaOH + H2

H4 The story of burningGreena Today we know that oxygen is gained when

something is burned.b oxygenc Lavoisier’s theory that there is something

joining during burning.1 a i D

ii Aiii Civ B

b upc Lavoisier’s theory.

Reda Today we know that oxygen is gained when

something is burned.b Lavoisier’s theory that there is something

joining during burning.c mercury oxide → mercury + oxygend The carbon and hydrogen in the solid wood are

burned to carbon dioxide and water vapourwhich are gases. These gases that go into the airaccount for the ‘mass loss’.

e Less than the original tin.1 a At B, the magnesium is added to the crucible.

At C, the magnesium begins to burn.At D, the magnesium has finished burning.

b There is a mass gain when the magnesiumwas burned.

c

d Collect the carbon dioxide and water vapourgases given off during the burning and weighthem.

e The total amount of the carbon dioxide givenoff during burning weighed more than thecarbon that was burned.

Mas

s in

gra

ms

Time in seconds

00

60 120 180 240

2.4

Book Answers.qxd 18-Jun-04 12:44 PM Page 22

Documents

H Using chemistry Unit guide - Physicslocker 3/Unit H.pdf · H Using chemistry Unit guide ... a list into two groups: natural and man-made. Brainstorming Pupils work in groups to