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Crude oil and fuels and Useful substances from crude oil
C1 Revision (higher)
114 minutes
114 marks
Page 1 of 43
Q1. Barbecues are heated by burning charcoal or burning hydrocarbons.
(a) Use the Chemistry Data Sheet to help you to answer this question.
The chemical equation for charcoal burning is:
C + O2 CO
2
Complete the word equation for this reaction.
carbon + ................................... carbon dioxide
(1)
(b) Propane is a hydrocarbon.
(i) Complete the displayed structure of propane. Draw in the missing bonds.
(1)
(ii) Write the chemical formula of propane. .................................................. (1)
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(iii) Draw a ring around the correct answer to complete the sentence.
(1)
(c) The table shows information about six hydrocarbons.
Tick ( ) two correct statements about the six hydrocarbons.
(2) (Total 6 marks)
hydrogen.
Propane burns in air to produce carbon dioxide and hydroxide.
water.
Hydrocarbon State at room
temperature (20°C) Boiling point in °C
Ethane (C2H
6) gas −89
Ethene (C2H
4) gas −104
Butane (C4H
10) gas −1
Butene (C4H
8) gas −6
Hexane (C6H
14) liquid +69
Hexene (C6H
12) liquid +64
Statement Tick ( )
Ethane and butane boil at temperatures less than 20°C.
Hexene and butene are alkanes.
Butane and hexane are liquid at 0°C.
Ethene and hexene each have a carbon-carbon double bond.
Q2. Crude oil is a mixture of many different chemical compounds.
(a) Fuels, such as petrol (gasoline), can be produced from crude oil.
(i) Fuels react with oxygen to release energy.
Name the type of reaction that releases energy from a fuel.
............................................................................................................... (1)
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(ii) Fuels react with oxygen to produce carbon dioxide. The reaction of a fuel with oxygen can produce a different oxide of carbon.
Name this different oxide of carbon and explain why it is produced.
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(b) Most of the compounds in crude oil are hydrocarbons. Hydrocarbons with the smallest molecules are very volatile.
In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.
Describe and explain how petrol is separated from the mixture of hydrocarbons in crude oil.
Page 4 of 43
Use the diagram and your knowledge to answer this question.
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(Total 9 marks)
Q3. This question is about oil reserves.
(a) Diesel is separated from crude oil by fractional distillation.
Describe the steps involved in the fractional distillation of crude oil.
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(b) Diesel is a mixture of lots of different alkanes.
What are alkanes?
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(c) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.
Petroleum products, such as petrol, are produced from crude oil. The graph shows the possible future production of petroleum products from crude oil and the expected demand for petroleum products.
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Canada’s oil sands hold about 20% of the world’s known crude oil reserves.
The oil sands contain between 10 to 15% of crude oil. This crude oil is mainly bitumen.
In Canada the oil sands are found in the ground underneath a very large area of forest. The trees are removed. Then large diggers and trucks remove 30 metres depth of soil and rock to reach the oil sands. The oil sands are quarried. Boiling water is mixed with the quarried oil sands to separate the bitumen from the sand. Methane (natural gas) is burned to heat the water.
The mixture can be separated because bitumen floats on water and the sand sinks to the bottom of the water. The bitumen is cracked and the products are separated by fractional distillation.
Use the information given and your knowledge and understanding to suggest the advantages and disadvantages of extracting petroleum products from oil sands.
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(Total 11 marks)
Q4. Crude oil is a mixture of mostly alkanes.
(a) Crude oil is separated into useful fractions by fractional distillation.
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(i) Describe and explain how the mixture of alkanes is separated by fractional distillation.
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(ii) The table gives the name and formula for each of the first three alkanes.
Complete the table to show the formula of butane.
(1)
Name of alkane Formula
Methane CH4
Ethane C2H
6
Propane C3H
8
Butane
(b) The structural formula of methane, CH4, is:
H │
H C H │ H
Draw the structural formula of propane, C3H
8
(1)
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(c) The relative amounts of and the market demand for some hydrocarbons from the fractional distillation of crude oil are shown in the graph.
(i) Why is the market demand for the C5 – C
8 fraction higher than the market demand for
the C21 – C
24 fraction?
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(ii) Cracking is used to break down large hydrocarbon molecules into smaller hydrocarbon molecules.
Complete the symbol equation by writing in the formula of the other hydrocarbon.
C20
H42 C
16H
34 + 2 ..........................................
(1)
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(iii) The C5 – C
8 fraction has low supply and high market demand.
Suggest three ways in which the oil industry could overcome this problem.
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(Total 10 marks)
Q5. Many human activities result in carbon dioxide emissions. Our carbon footprint is a measure of how much carbon dioxide we each cause to be produced.
(a) Why should we be concerned about our carbon footprint?
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(b) Most power stations in the UK burn coal. Coal was formed from tree-like plants over millions of years.
Suggest why burning wood instead of coal would help to reduce our carbon footprint.
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(Total 4 marks)
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Q6. Crude oil is a mixture of hydrocarbons. Most of these hydrocarbons are alkanes.
(a) The general formula of an alkane is CnH
2n+2
Complete the structural formula for the alkane that has six carbon atoms in its molecules.
(1)
(b) The boiling points of alkanes are linked to the number of carbon atoms in their molecules.
(i) Describe the link between the number of carbon atoms in an alkane molecule and its boiling point.
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(ii) Suggest two reasons why all of the alkanes in the bar chart are better fuels than the alkane with the formula C
30H
62
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(c) During the last 200 million years the carbon cycle has maintained the percentage of carbon dioxide in the atmosphere at about 0.03 %. Over the last 100 years the percentage of carbon dioxide in the atmosphere has increased to about 0.04 %. Most of this increase is caused by burning fossil fuels to heat buildings, to generate electricity and to power our transport. Fossil fuels contain carbon that has been locked up for millions of years.
(i) Burning fossil fuels, such as petrol, releases this locked up carbon. Balance the chemical equation for the combustion of one of the alkanes in petrol.
(1)
2 C8H
18
+ 25 O2
........ CO
2
+ ........ H2O
(ii) Where did the carbon that is locked up in fossil fuels come from?
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(iii) The burning of fossil fuels has caused the percentage of carbon dioxide in the atmosphere to increase to above 0.03 %. Explain why.
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(Total 8 marks)
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Q7. Petroleum diesel is produced from crude oil.
Most vehicles that use petroleum diesel as fuel can also use biodiesel or a mixture of these two fuels. In the UK (in 2010) there must be 5 % biodiesel in all petroleum diesel fuel.
Biodiesel is produced from plant oils such as soya. The crops used to produce biodiesel can also be used to feed humans. The benefit that biodiesel is ‘carbon neutral’ is outweighed by the increasing demand for crops. This increasing demand is causing forests to be burnt to provide land for crops to produce biodiesel. Only a huge fall in the price of petroleum diesel would halt the increasing use of biodiesel.
The graph shows the average percentage change in exhaust emissions from vehicles using different mixtures of petroleum diesel and biodiesel.
There is no difference in carbon dioxide emissions for all mixtures of petroleum diesel and biodiesel.
Use the information and your knowledge and understanding to evaluate the use of plant oils to produce biodiesel.
Remember to give a conclusion to your evaluation.
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(Total 5 marks)
Q8. The table shows how much carbon dioxide is produced when you transfer the same amount of energy by burning coal, gas and oil.
(a) Use the information from the table to complete the bar-chart. (2)
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(b) The second bar-chart shows how much sulphur dioxide is produced by burning the same three fuels.
Compare the amount of sulphur produced by burning gas with the amount produced by burning coal.
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(c) Burning fuels also produces nitrogen oxides, even though the fuels contain no nitrogen. Explain why this happens.
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(d) When you release the same amount of energy from coal, gas and oil, different amounts of carbon dioxide are produced. Use the information below to explain why.
(3)
(e) What other element do coal and oil usually contain?
..................................................................................................................................... (1)
(Total 9 marks)
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Q9. Crude oil is used to produce poly(ethene).
(a) Fractional distillation is used to separate crude oil into fractions.
(i) Write a number, 2, 3, 4 or 5, next to each stage so that the description of fractional distillation is in the correct order. Numbers 1 and 6 have been done for you.
(2)
Number Stage
1 The crude oil is heated to 350 °C.
When a fraction in the vapours cools to its boiling point, the fraction condenses.
Any liquids flow down to the bottom of the column and the hot vapours rise up the column.
6 The condensed fraction is separated and flows out through a pipe.
When the hot vapours rise up the column, the vapours cool.
Most of the compounds in the crude oil evaporate.
(ii) The naphtha fraction is cracked to produce ethene (C2H
4).
Ethene is used to make the polymer called poly(ethene).
Name two substances produced when poly(ethene) burns in air.
1 ............................................................................................................
2 ............................................................................................................ (2)
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(b) In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.
Each year in the UK, billions of plastic bags are given free to shoppers. These bags are made from poly(ethene) and are often used only once. After being used many of these plastic bags are either thrown away as litter or buried in landfill sites.
In 2006 over 10 billion of these plastic bags were given free to shoppers. In 2009 the number of plastic bags given to shoppers had decreased to 6.1 billion. One reason for the decrease was because some supermarkets made people pay for their plastic bags.
From 2011 a new type of plastic shopping bag made mainly from poly(ethene) had a use-by date of only one year printed on the bag.
Use the information above and your knowledge and understanding to describe advantages and disadvantages of using plastic shopping bags made from poly(ethene).
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(Total 10 marks)
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Q10. The diagram shows a reaction which takes place in an oil refinery.
(a) X, Y and Z are all examples of which type of compound?
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(b) What type of chemical reaction takes place when compound X is converted into compounds Y and Z?
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(c) Compounds Y and Z are both useful substances.
Compound Y is unsaturated. Compound Z is saturated.
(i) Suggest one use for compound Y.
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(ii) Suggest one use for compound Z.
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(Total 4 marks)
Q11. Known crude oil reserves are being used up rapidly. Crude oil is used to produce many useful fuels, such as petrol. One way to conserve crude oil reserves would be to increase the production of bio-fuels.
(a) Ethanol can be produced for use as a bio-fuel. Cars can be powered by ethanol or ethanol–petrol mixtures.
Sugar cane can be fermented to give a mixture of water (boiling point 100 °C) and ethanol (boiling point 78 °C).
(i) How can ethanol be separated from water?
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(ii) Ethanol, C2H
5OH, burns to release heat energy.
Complete the balanced symbol equation by writing in the formulae of the two products.
C2H
5OH + 3O
2 2......... + 3.........
(2)
(b) The cost of producing a bio-fuel, such as ethanol, by fermentation, is at least three times higher than the production cost of petrol. It costs less to produce ethanol from alkanes. In the production, the vapour of an alkane is passed over a hot catalyst.
Ethene is then converted into ethanol.
(i) What has happened to the hexane to produce ethene?
.......................................................................................................................... (1)
(ii) Complete the structural formula for ethene, C2H
4.
C C (1)
(iii) Name the compound that is added to ethene to produce ethanol, C2H
5OH.
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(c) As explained in parts (a) and (b), ethanol can be made using either sugar or alkanes as the starting material.
Evaluate the advantages and disadvantages of using these two starting materials to produce ethanol.
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(Total 10 marks)
Q12. Petrol sold in most countries now contains at least 5% ethanol. The production of ethanol, for use as a fuel, is being increased.
The flow diagram shows how ethanol can be produced from crude oil.
(a) Why does crude oil need to be fractionally distilled?
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(b) Hydrocarbons, such as decane, in the naphtha fraction are cracked to produce ethene. The balanced chemical equation shows the cracking of decane.
(i) Describe how cracking is done.
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C10
H22 →
decane
C8H
18 +
octane
C2H
4
ethene
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(ii) Complete the structural formula of ethene by drawing lines to represent each covalent bond.
(1)
H H
C C
H H
(c) The flow diagram below shows how ethanol, for use as a fuel, can also be produced from food crops.
Use the information in the two flow diagrams and your own knowledge and understanding to evaluate whether more of this ethanol should be produced from food crops or from crude oil.
Remember to give a conclusion to your evaluation.
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(Total 9 marks)
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Q13. This question is about the use hydrocarbons and the production of compounds from hydrocarbons.
(a) The equation shows a reaction involving hydrocarbons.
C8H
18 → C
2H
4 + C
6H
14
Hydrocarbon J Hydrocarbon K Hydrocarbon L
Choose the correct processes from the box to complete the sentences.
combustion hydration thermal decomposition polymerisation
(i) Hydrocarbons K and L are produced by ........................................... . (1)
(ii) Ethanol can be produced from hydrocarbon K by .............................. . (1)
(iii) Describe a test to distinguish between hydrocarbons K and L and give the result of the test.
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(b) Hydrocarbon J burns completely in oxygen to produce carbon dioxide and water vapour.
2 C8H
18 + 25 O
2 → 16 CO
2 + 18 H
2O
(i) When 114g of hydrocarbon J burns completely in 400g of oxygen it produces 162g of water vapour.
What mass of carbon dioxide would be produced from burning 114g of hydrocarbon J?
Show clearly how you work out your answer
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Answer = ................................. g (2)
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(ii) The mass of carbon dioxide produced is greater than the 114g of hydrocarbon J that was burned. Explain why.
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(c) Two different processes are used to produce ethanol.
Process 1 Process 2
Fermentation of a sugar solution by yeast in a reaction vessel.
The reaction vessel has to be emptied, cleaned and refilled every few days.
The process produces a 15% ethanol solution in water.
Reaction of ethene (from crude oil) with steam in a reactor.
The reaction is only stopped if there is a fault in the reactor.
The process produces 100% ethanol.
(i) Give one advantage that Process 1 has over Process 2.
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(ii) What advantages to a manufacturer of ethanol, does Process 2 have over Process 1?
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(Total 11 marks)
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Q14. The equation below shows the cracking of a hydrocarbon compound into two different compounds, A and B.
(a) State two differences between the structures of compounds A and B.
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(b) Why is compound A useful in industry?
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(Total 3 marks)
Q15. Poly(ethene) is a long-chain saturated hydrocarbon. The formula for part of the polymer chain is:
(a) Write the structural formula of the small molecule from which poly(ethene) is made.
(2)
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(b) Saturated hydrocarbons, such as propane, are fuels.
Write a balanced equation for the complete combustion of propane, C3H
8.
............................ + ............................ → ............................ + ............................. (3)
(Total 5 marks)
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M1. (a) oxygen
must be name do not accept oxide or dioxide
1
(b) (i) 2 x C–C
and
5 x C–H all single (line) bonds
1
(ii) C3 H
8
must be formula do not accept lower case h
1
(iii) water 1
(c) ethane and butane boil at temperatures less than 20°C 1
ethene and hexene each have a carbon-carbon double bond 1
[6]
M2. (a) (i) exothermic
accept combustion allow burning or oxidation or redox
1
(ii) carbon monoxide / CO (is produced) allow monoxide (is produced) ignore carbon oxide
1
because there is incomplete / partial combustion (of the fuel) accept because there is insufficient oxygen / air (to burn the fuel)
1
(b) Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response. Examiners should also refer to the information in the Marking guidance.
0 marks No relevant content.
Level 1 (1-2 marks) There is a statement that crude oil is heated or that substances are cooled. However there is little detail and any description may be confused or inaccurate.
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Level 2 (3-4 marks) There is some description of heating / evaporating crude oil and either fractions have different boiling points or there is an indication of a temperature difference in the column.
Level 3 (5-6 marks) There is a reasonable explanation of how petrol is or fractions are separated from crude oil using evaporating and condensing.
If cracking is given as a preliminary or subsequent process to fractional distillation then ignore.
However, if cracking / catalyst is given as part of the process, maximum is level 2.
Examples of chemistry points made in the response could include:
• Some / most of the hydrocarbons (or petrol) evaporate / form vapours or gases
• When some of / a fraction of the hydrocarbons (or petrol) cool to their boiling point they condense
• Hydrocarbons (or petrol) that have (relatively) low boiling points and are collected near the top of the fractionating column or hydrocarbons with (relatively) high boiling points are collected near the bottom of the fractionating column
• The process is fractional distillation
• Heat the crude oil / mixture of hydrocarbons or crude oil / mixture is heated to about 350°C
• Some of the hydrocarbons remain as liquids
• Liquids flow to the bottom of the fractionating column
• Vapours / gases rise up the fractionating column
• Vapours / gases cool as they rise up the fractionating column
• The condensed fraction (or petrol) separates from the vapours / gases and flows out through a pipe
• Some of the hydrocarbons remain as vapours / gases
• Some vapours / gases rise out of the top of the fractionating column
• There is a temperature gradient in the fractionating column or the fractionating column is cool at the top and hot at the bottom
6 [9]
M3. (a) heat to vaporise (the crude oil)
do not accept cracking / burning 1
vapours condense 1
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at different temperatures allow they have different boiling points
1
(b) (alkanes) are hydrocarbons or are compounds of hydrogen and carbon only 1
alkanes are saturated or have only (carbon-carbon) single bonds
accept have no (carbon-carbon) double bonds accept general formula is C
nH
2n+2 for 2 marks
1
(c) Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response.
0 marks No relevant content.
Level 1 (1-2 marks) There is a basic description of at least one advantage or one disadvantage of extracting petroleum products from oil sands.
Level 2 (3-4 marks) There is a clear description of an advantage and a disadvantage of extracting petroleum products from oil sands.
Level 3 (5-6 marks) There is a detailed description of both advantages and disadvantages of extracting petroleum products from oil sands.
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Examples of the chemistry/environmental/economic/social points made in the response
Advantages:
• the oil sands are needed because crude oil is running out
• this crude oil is needed because demand is increasing
• the oil sands contain a large amount of crude oil
• the oil sands could improve Canada’s economy
• the oil sands provide employment for a lot of people
• the trees / forest are used for wood products / fuel
Disadvantages:
• destruction of environment / habitats
• fewer trees / forests to absorb carbon dioxide
• specified pollution, for example, visual, noise, atmospheric (including dust), water (including river or drinking) with cause, e.g. gases / particulates from burning diesel
• large amounts of methane (natural gas) are used to provide energy
• energy / fuel needed for cracking and fractional distillation
• burning fuel releases carbon dioxide
• crude oil / natural gas contains locked up carbon
• crude oil is non-renewable 6
[11]
M4. (a) (i) heat / evaporate the crude oil / change to gas or vapour
do not accept heat with catalyst 1
cool / condense (hydrocarbons) allow small molecules at top and / or large molecules at bottom
1
at different temperatures / boiling points if the answer describes cracking ‘ no marks
1
(ii) C4H
10
1
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(b) H H H │ │ │ H ─C ─ C ─ C ─ H │ │ │ H H H
1
(c) (i) C5 to C
8 fraction are fuels or easier to burn or petrol (fraction)
accept C21 to C
24 fraction not useful as fuels
do not accept produce more energy 1
(ii) C2H
4
do not accept C4H
8
1
(iii) any three from:
• use different / lighter crude oils
• develop markets for low demand fractions
• develop new techniques / equipment to use low demand fractions as fuels
• cracking
• convert low demand fractions to high demand fractions or bigger molecules to smaller molecules
• develop alternative / bio fuels do not accept price
3 [10]
M5. (a) (thought to cause) global warming / green house (effect) / climate change
ignore other consequences of global warming do not accept acid rain / ozone layer / global dimming
1
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(b) any three from:
• replant trees / renewable / sustainable ignore reusable
• carbon (dioxide) used by trees / photosynthesis accept trees absorb carbon (dioxide) as they grow ignore respiration
• it is a (continuous / carbon) cycle accept burning wood is carbon neutral
or carbon (dioxide) goes back into the air
for the second and third bullet points: accept trees use carbon dioxide which is released when (trees / wood are / is) burnt for 2 marks
• no new carbon (dioxide) is produced
or no locked up carbon (dioxide) is released
or the carbon (dioxide) was absorbed millions of years ago
3 [4]
M6. (a) complete diagram with 2 carbon atoms and 5 hydrogen atoms each C–C and each C–H linked by a single line (bond)
1
(b) (i) the greater the number of (carbon) atoms (in an alkane molecule) the greater its boiling point or vice versa
allow as the (carbon) chain gets longer the boiling point increases ignore melting points do not accept reference to greater number of molecules
1
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(ii) they = hydrocarbons from the graph it = C
30H
62
any two from:
• low boiling point / volatile accept they are gases or liquids
• low viscosity
• high flammability accept easier to burn / ignite
• small molecules accept short chains ignore number of carbon atoms
• burn completely ignore speed of burning
2
(c) (i) 16 (CO2) + 18 (H
2O)
1
(ii) (carbon dioxide in the Earth’s early) atmosphere accept from volcanoes (millions of years ago) or from dead plants / animals allow dead sea creatures ignore shells
1
(iii) increase in burning / use of fossil fuels 1
locked up carbon (carbon dioxide) is released allow carbon / carbon dioxide from millions of years ago is released accept extra carbon dioxide is not ‘absorbed’ (by the carbon cycle)
1 [8]
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M7. any four from:
to gain 4 marks both pros and cons should be given
Arguments for biodiesel
max three from:
• sustainable / renewable
• (carbon neutral) absorbs CO2 when growing / during photosynthesis
• burning biodiesel produces low amounts particulates / carbon monoxide allow burning biodiesel produces little / low amount of global dimming ignore sulfur dioxide
• can use waste vegetable oils / fats (from food industry) or can use waste plant material
• can be used to conserve crude oil (instead of / mixed with petroleum diesel)
• produced by a low energy / temperature process accept produced by a low tech process
• biodegrades (easily) ignore engine effects
Arguments against biodiesel
max three from:
• creates food shortages accept price of food increases
• deforestation to plant more crops leads to loss of habitat / biodiversity or deforestation leads to a reduction in absorption of CO
2
allow burning trees increases CO2
allow deforestation increases global warming
• burning biodiesel produces high amounts of nitrogen oxides allow increases acid rain
• crops takes time to grow allow crops can fail
• vast areas of land needed to grow crops 4
conclusion supported by the argument presented, which must give added value to the points for and against given above
1 [5]
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M8. (a) both bars correct height (to better than half a square)
1 mark for both
both bars correctly labelled (w.r.t. relative heights if these incorrect)
for 1 mark 2
(b) a lot less / much less / 18 times less (converse must specify coal) gains 1 mark
1
(c) ideas that
• at high temperatures (produced when fuels burn)
• nitrogen and oxygen from air / atmosphere combine / react or nitrogen from air / atmosphere oxidises
for 1 mark each 2
(d) ideas that
• coal produces most carbon dioxide / more CO2 than gas / oil
• because coal is (mostly) carbon
• gas produces less carbon dioxide than coal / oil
• oil and gas also contain hydrogen / contain more hydrogen atoms than carbon atoms / also produce water
any three for 1 mark each 3
(e) sulphur for 1 mark
2 [9]
M9. (a) (i) (1)
5
3
(6)
4
2 all numbers in the correct order gains both marks any two numbers in the correct position gains 1 mark
2
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(ii) Water ignore formula if correct name given accept hydrogen oxide allow H
2O
1
carbon dioxide allow CO
2
accept carbon monoxide / CO or carbon / C 1
(b) Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response. Examiners should also apply a � best-fit� approach to the marking.
0 marks No relevant content.
Level 1 (1-2 marks) There is a basic description of at least one advantage or one disadvantage caused by using plastic shopping bags made from poly(ethene)
Level 2 (3-4 marks) There is a clear description of both an advantage and a disadvantage, caused by using plastic shopping bags made from poly(ethene).
Level 3 (5-6 marks) There is a detailed description of both advantages and disadvantages caused by using plastic shopping bags made from poly(ethene)
examples of the chemistry/social points made in the response: ignore cost unqualified
Advantages:
• Simple properties eg strong / low density / water resistant
• Bags can be reused (for shopping) or another specified use eg bin liners
• Money charged for bags can go to good causes or encourage reuse
• Poly(ethene) bags can be recycled eg made into milk bottle crates
• Poly(ethene) bags can be burned to provide heat for buildings/generation of electricity
• New bags are now made that can biodegrade
Disadvantages:
• (Older) bags can take many years to biodegrade
• There is a shortage of landfill space
• Bags are made from (crude) oil which is a non-renewable resource/running out
• Large amounts of energy/fuel are used for the production of poly(ethene)
• Production of poly(ethene) releases carbon dioxide/causes global warming
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• Specified issue caused by litter eg visual pollution or effect on wildlife
• Burning bags release carbon dioxide / causes global warming 6
[10]
M10. (a) hydrocarbon 1
(b) thermal decomposition / cracking 1
(c) (i) making polymers / poly(e)thene accept plastic (bags)
1
(ii) fuel 1
[4]
M11. (a) (i) by (fractional) distillation
accept a description of the distillation process (heat and how separation works) eg heat and condense accept boil / vapourise etc for heat
or
fractionation 1
(ii) CO2
note the order of these products must be correct 1
H2O
wrong way round = 1 mark 1
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(b) (i) (hexane) has been broken down (into smaller hydrocarbons / molecules) 1
accept (thermal) decomposition / cracked / split / broken up owtte
(ii) H H │ │ C = C │ │ H H
accept CH2 = CH
2
1
(iii) water / hydrogen oxide / steam accept H
2O
1
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(c) candidates must include both sugar cane and crude oil in their evaluation and both an advantage and a disadvantage to gain full marks. if they do not then the maximum mark is three
any four from:
advantages of using sugar
• country has no wealth to buy (large quantities of) crude oil not ‘expensive’ alone
• country has limited technological development
or
underdeveloped / third world country
• able / suitable climate to grow sugar cane
• enough land to grow sugar cane / land cannot be used to grow food / deforestation
• sugar is a renewable source
or
crude oil is a non-renewable resource / finite resource / limited resources
• CO2 / carbon neutral
advantages of using alkanes:
• economic costs are low
• continuous process
• country has large oil resources
• country has oil refineries / cracking plants
• very pure product
• faster process 4
[10]
M12. (a) it is a mixture (of hydrocarbons) or contains hydrocarbons with different boiling points
accept to separate (crude) oil (into fractions) or obtain the naphtha (fraction) accept to get useful products ignore removal of impurities
1
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(b) (i) heat / vaporise mention of hydrogen = max 1 accept thermal (decomposition) for heat allow boil do not allow temperatures below 100°C ignore steam
1
catalyst allow alumina / porous pot ignore other catalysts
1
(ii) 4 × C – H and C = C
ignore brackets with or without an ‘n’ before them do not allow poly(ethene)
1
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(c) ignore ideas about carbon dioxide formation / photosynthesis or cost / economics / environmentally friendly
any four from:
candidates are only awarded 1 mark if they use equivalent pairs of bulleted points
must be at least one advantage and one disadvantage for all four marks
crops advantages eg:
crude oil disadvantages eg:
• renewable (resource) / sustainable • non-renewable (resource) / finite / running out
• low / less energy / fuel needed for process or lower temperature [ignore heat or quoted temperatures]
• high / more energy needed for process or/ higher temperature
• can use waste plant / crop material
• carbon neutral • not carbon neutral or releases locked up carbon
• low safety risk (processes) • high safety risk (process)
• low technology • high technology • risk of major oil spillage • can be used to make other products
disadvantages eg: advantages eg:
• batch process / process is slow • continuous process / process is fast
• many steps in the process • few steps in the process
• ethanol is impure / may contain water • ethanol is pure
• food shortages • ‘conserves’ food
• need very large areas of (arable) land to grow crops or can only grow in certain areas / climates
• destruction of woodland / habitat
• slow growth of crops
• labour intensive • can accept reverse arguments
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4
a conclusion with a reasoned argument based on valid advantages and disadvantages
there must be at least one advantage and one disadvantage, however, a matched pair, although only awarded one mark would allow the conclusion mark to be awarded
1 [9]
M13. (a) (i) thermal decomposition 1
(ii) hydration 1
(iii) add bromine (water)/iodine solution (to K and L) 1
K will decolourise these solutions or L will not decolourise these solutions
1
(b) (i) 352 (g) for correct answer if answer is incorrect 400 + 114 – 162 gains 1 mark
2
(ii) because 2 molecules of hydrocarbon J had 25 molecules of oxygen added
or
because 2 molecules of hydrocarbon J produced 16 molecules of carbon dioxide
allow because oxygen has been added to hydrocarbon J for 1 mark
2
(c) (i) raw materials are renewable accept does not use crude oil
1
(ii) alcohol does not need to be distilled accept alcohol produced is pure
1
process is continuous 1
[11]
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##
(a) Compound A has fewer C atoms or Compound B has fewer H atoms
Compound A has C = C/double bond or Compound A is unsaturated
each for 1 mark (accept converse i.e compound B has not ...)
2
(b) Compound A is reactive or can be used to make many substances or can be used in polymerisation/making plastics/named plastic or can be used as a fuel
any one for 1 mark 1
[3]
M15. (a) C=C
do not accept C2H
4
1
four Hs only, two attached to each carbon credit CH
2CH
2 for two marks
1
(b) C3H
8 + 5O
2 → 3CO
2 + 4H
2O
two correct formulae LHS 1
can be in either order two correct formulae RHS
1
can be in either order correctly balanced, consequential marking allowed for 10 O
1 [5]
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