9
Centre Number Candidate Number Candidate Name International General Certificate of Secondary Education UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS SYNDICATE CHEMISTRY PAPER3 0620/3 Thursday 9 NOVEMBER 2000 Morning 1 hour 15 minutes Candidates answer on the question paper. Additional materials: Electronic calculator and/or Mathematical tables TIME 1 hour 15 minutes INSTRUCTIONS TO CANDIDATES Write your name, Centre number and candidate number in the spaces at the top of this page. Answer all questions. Write your answers in the spaces provided on the question paper. INFORMATION FOR CANDIDATES The number of marks is given in brackets [ ] at the end of each question or part question. Mathematical tables are available. You may use a calculator. A copy of the Periodic Table is printed on page 12. This question paper consists of 10 printed pages and 2 blank pages. S8 (SLC/TC) OK07569/2 @ UCLES 2000 [Turn over FOR EXAMINER'S USE 1 2 3 4 5 TOTAL

Candidate Centre Number Number Candidate · PDF fileCandidate Number Candidate Name International General Certificate of Secondary Education UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS

Embed Size (px)

Citation preview

Page 1: Candidate Centre Number Number Candidate · PDF fileCandidate Number Candidate Name International General Certificate of Secondary Education UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS

Centre NumberCandidateNumber

Candidate Name

International General Certificate of Secondary Education

UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS SYNDICATE

CHEMISTRYPAPER3

0620/3

Thursday 9 NOVEMBER 2000 Morning 1 hour 15 minutes

Candidates answer on the question paper.Additional materials:

Electronic calculator and/or Mathematical tables

TIME 1 hour 15 minutes

INSTRUCTIONS TO CANDIDATES

Write your name, Centre number and candidate number in the spaces at the top of this page.

Answer all questions.

Write your answers in the spaces provided on the question paper.

INFORMATION FOR CANDIDATES

The number of marks is given in brackets [ ] at the end of each question or part question.Mathematical tables are available.

You may use a calculator.

A copy of the Periodic Table is printed on page 12.

This question paper consists of 10 printed pages and 2 blank pages.

S8 (SLC/TC) OK07569/2@ UCLES 2000 [Turn over

FOR EXAMINER'S USE

1

2

3

4

5

TOTAL

Page 2: Candidate Centre Number Number Candidate · PDF fileCandidate Number Candidate Name International General Certificate of Secondary Education UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS

2Ex

1 The element scandium, proton (atomic) number, Z = 21, was discovered by L Nilson inSweden in 1879.

(a) It forms only one ion which has the formula ~~SC3+.

(i) How many electrons, protons and neutrons are there in this ion?

number of electrons .........

number of protons. ......................

number of neutrons """"""""""""""""""""""""""""""""""".............................

(ii) Predict the electron distribution of this ion.

""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" .

[4]

(b) The main ore of scandium is thortveitite, Sc2Si2Oy' This is converted into scandiumfluoride which reacts with calcium to produce scandium metal.

(i) Balance the ionic equation for the reaction between scandium fluoride and calcium.

Ca + SC3+ ~ Ca2+ + sc [1]

(ii) Which change in the above reaction is oxidation? Give a reason for your choice.

................

...................................................................................................................................

.[2]

(iii) An alternative method of extracting scandium is by the electrolysis of a moltenmixture that contains scandium chloride. Write ionic equations for the reactions atthe electrodes.

reaction at cathode ...................................................................................................

reaction at anode ...[2]

(c) The density of scandium is 2.99 g/cm3 and it has only one valency of three. Scandiumcompounds are white solids and form colourless solutions. Titanium is a more typicaltransition metal, predict how its properties would be different from those of scandium.

t..........................................................................................................................................

..........

[2]

Page 3: Candidate Centre Number Number Candidate · PDF fileCandidate Number Candidate Name International General Certificate of Secondary Education UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS

3

(d) A 43 9 sample of scandium. ore, Sc2Si2O7produced 129 of scandium. Calculate thepercentage yield by completing the following calculation.

The mass of one mole of Sc2Si2O7 is 258 9

Number of moles of Sc2Si207 in 43 9 of the ore = ............

One mole of Sc2Si207will give moles of Sc

43g of Sc2Si207will produce moles of Sc

43 9 of Sc2Si2O7will produce g of Sc

Percentage yield of scandium = ............................

- ............................ [5]

Page 4: Candidate Centre Number Number Candidate · PDF fileCandidate Number Candidate Name International General Certificate of Secondary Education UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS

4

2 The diagram below shows a correctly constructed concrete floor.

VO~'O O.\C)C/O..O O.\C)C./O. .0 O.\C)C/O--:.O O.\C)C./O 0

.:;:.. O' 0°.0:;: 0 =:°.0:; 0 C::,°.0:;: 0 =O. ° :;:.0 c::,.00 .'O~ ..<:::>.°q7:\0 .OC:I7>.<:::>

.

.. oo~oo.om

.

. °o27Ot1?>.°o ~.<:::>

.

.

.

270 .~

..

.o .'. a W c:> 0 W ao ~ 0 ~o . '<4:J 0 . ~o .. a W . <:

~o°<:::>°o~ ~~o<:::>°o~~o°<:::>°o~. ~0°<:::>°0<:::>5: ~oo~o(

sheet of poly( ethene) toprevent water rising

concrete mixed with

poly(propene) fibressteel reinforcingrods

(a) (i) What type of reaction is used to make both of the polymers, poly(ethene) andpoly(propene)?

.. ......

(ii) A diagram of the structure of poly(ethene) is given below.

H H

I Ic-cI I

H H

Draw a similar diagram to show the structure of poly(propene).

[3]

Page 5: Candidate Centre Number Number Candidate · PDF fileCandidate Number Candidate Name International General Certificate of Secondary Education UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS

5

(b) (i) Iron from the blast furnace is impure. It contains about 5% of carbon and of otherimpurities such as silicon and sulphur. Describe how this impure iron is convertedinto mild steel.

...................................................................................................................................

"""""""""""'" ... .....

...................................................................................................................................

"""""'" ... [4]

(ii) The steel reinforcing rods might be galvanised. Explain what is meant bygalvanising and how this will decrease the rate at which the rods corrode.

.. ...

...................................................................................................................................

"""""""""""""'" ... ... .[3]

(c) Two of the chemicals used to make concrete are limestone and sand. Limestone is anionic compound, containing the ions Ca2+andCO32-.Sand is mainly an oxide of siliconwhich is macromolecular.

I

I

I

0

I

Si

O/'~O// 0 """ I "

(i) What is the valency of

calcium in calcium carbonate, ........................................................................

silicon in this oxide? ........................................................................

(ii) What is the electron distribution in one atom of

calcium, .

. silicon? .

(iii) Explain why the metal calcium forms ionic bonds but the non-metal silicon formscovalent bonds.

...................................................................................................................................

...................................................................................................................................[6]

Page 6: Candidate Centre Number Number Candidate · PDF fileCandidate Number Candidate Name International General Certificate of Secondary Education UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS

6

3 Organic compounds that contain the halogens can have chloro, bromo or iodo in their names.

(a) The following diagram shows the structure of 1-bromobutane.

H H H H

I I I I

H-C-C-C-C-Br

I I I I

H H H H

(i) Draw the structure of an isomer of this compound.

(ii) Draw a possible structure of a dibromobutane.

(iii) Name two chemicals that react together to make only one product -dibromobutane.

and """""""""""""""""""""""""""""""'[4j..

(b) Draw a diagram to show the arrangement of the valency electrons in the covalentcompound chloromethane.Use 0 to represent an electron from carbonUse x to represent an electron from hydrogenUse <8>to represent an electron from chlorine

Page 7: Candidate Centre Number Number Candidate · PDF fileCandidate Number Candidate Name International General Certificate of Secondary Education UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS

7

(c) Organic halides react with water to form an alcohol and a halide ion.The halogen present in an organic compound can be determined by identifying thehalide ion.

CH3CH2Br + H2O ~ CH3CH2OH + H+ + Br-bromoethane + water ethanol bromide ion

(i) Name the alcohol formed when 1-bromobutane reacts with water.

...................................................................................................................................

(ii) Describe how you could test for the bromide ion.

reagent used .............................................................................................................

result of test ....................

(iii) Suggest an explanation for the following observations.Bromine was bubbled through a solution containing a halide ion. The solutionturned dark brown.

...................................................................................................................................

... ......[5]

(d) The rate of reaction between an organic halide and water can be studied in the followingexperiment.

A mixture of 10 cm3 of aqueous silver nitrate and 10 cm3 of ethanol are warmed to60 DC.Drops of the organic halide are added and the time taken for a precipitate to formis measured.

The reaction produces halide ions which react with the silver nitrate to give a precipitateof a silver halide. The results are given in the table.

(i) Write the three organic halides in order of reactivity with water.

most reactive

tleast reactive

(ii) Explain why it takes longer to produce the precipitate in experiment A than in B.

...................................................................................................................................

.[3]

experiment organic halide number of drops time/min

A bromobutane 4 5

B bromobutane 8 2

C chlorobutane 4 100

D iodobutane 4 0.1

Page 8: Candidate Centre Number Number Candidate · PDF fileCandidate Number Candidate Name International General Certificate of Secondary Education UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS

8

4 The two non-metals, sulphur and selenium, are in Group VI.

(a) Sulphuric acid is made from sulphur. This acid is used to make detergents calledsulphonates. A hydrocarbon is made to react with oleum (fuming sulphuric acid) to formsulphonic acids. These form salts called sulphonates.

(i) Complete the word equations for some reactions of a sulphonic acid.

magnesium + sulphonic ~ magnesium + ...........................acid sulphonate

sodium + sulphonic ~ + + water.carbonate acid

......................

(ii) Sulphonate ions are of the type RSO3-, where R is an organic group.What is the formula of magnesium sulphonate?

... "" .........................

(iii) How is oleum made in the Contact Process?

.. """""

................

(iv) How is oleum changed into concentrated sulphuric acid?

........[7]

(b) Insoluble and soluble sulphates can each be made from dilute sulphuric acid. Describehow a pure sample of the insoluble salt, lead(II) sulphate, can be made.

.......

........

..........................................................................................................................................

[4]

(c) Predict two chemical properties of the non-metal selenium.

....................

.. ... [2]

(d) Selenium is used to make a device that can change light energy into electrical energy.

(i) Name the process used in green plants to change light energy into chemical energy.

... ..............

(ii) Explain how a liquid fuel can be obtained from plant material.

""""""""""""""""""""""""""""'"..............

........

M~"IO Mnunn [3]

Page 9: Candidate Centre Number Number Candidate · PDF fileCandidate Number Candidate Name International General Certificate of Secondary Education UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS

9

5 Chemistry is concerned with problem-solving and answering questions. For each of thefollowing, describe any experiments that are needed and, when necessary, indicate how theresults should be used to solve the problem.

(a) Nickel sulphate-7-water exists as bright green crystals and anhydrous nickel sulphateas a yellow powder. How could you show that the action of heat on the hydrated salt is areversible reaction?

.........................

...................................................................................................

[3]

(b) How could you prove that the percentage of water in an aqueous solution of sodiumchloride is 74%?

... ...

..............................................................................

[4]

(c) A small piece of cement from a wall is dissolved in nitric acid. The resulting mixture isfiltered to give a solution.

(i) What observation shows that the cement contains carbonate ions and what test isneeded to confirm this?

observation ......................................................................

test ............................................................................................................................

result ..........

(ii) How could you show that the solution contains calcium ions?

reagent ......

result .........................

reagent ......

result [6]

(d) The formula of an acid is either of the type HY or H2Y. How could you find out which oneis correct by using aqueous solutions of the acid and of sodium hydroxide. Assume thatboth solutions have the same concentration, 0.1mol/dm3.

.

.

..........................................................................................................................................

[4]0620/3 NovOO