Paper 2

Centre Number

Candidate Number

Candidate Name

UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS SYNDICATE Joint Examination for the School Certificate and General Certificate of Education Ordinary Level

5070/2

CHEMISTRY PAPER 2 Theory Tuesday

16 NOVEMBER 1999

1 hour 30 minutes

Candidates answer on the question paper. Additional materials: Answer paper Mathematical tables or calculator

TIME

1 hour 30 minutes

INSTRUCTIONS TO CANDIDATES Write your name, Centre number and candidate number in the spaces at the top of this page and on any separate answer paper used. Section A Answer all questions. Write your answers in the spaces provided on the question paper. Section B Answer any three questions. Write your answers on the lined pages provided and, if necessary, continue on separate answer paper. At the end of the examination, fasten any separate answer paper securely to the question paper. INFORMATION FOR CANDIDATES The number of marks is given in brackets [ ] at the end of each question or part question. A copy of the Periodic Table is printed on page 16. Mathematical tables are available. You may use a calculator.

FOR EXAMINER’S USE

Section A B9 B10 B11 B12 TOTAL

This question paper consists of 13 printed pages and 3 lined pages. SB (SLC) QK94131/4 © UCLES 1999

[Turn over

2 Section A Answer all questions in the spaces provided. The total mark for this section is 45.

A1 This question is concerned with the following list of substances. potassium

lead(II) bromide

oxygen

zinc oxide

hydrogen

carbon

Each substance can be used once, more than once, or not at all. Name a substance from the list above which (a) reacts violently with water, ......................................................................................................................................[1] (b) conducts electricity when molten but not when solid, ......................................................................................................................................[1] (c) is amphoteric, ......................................................................................................................................[1] (d) has a formula of the type XY2, ......................................................................................................................................[1] (e) has an allotrope with a structure similar to that of silica, ......................................................................................................................................[1] (f)

has a low boiling point, ......................................................................................................................................[1]

(g) is produced at the cathode during electrolysis of dilute sulphuric acid. ......................................................................................................................................[1]

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For Examiner’s Use

For Examiner’s Use

3 A2 The graph below shows the heating curve for a pure substance. 300

200 temperature / °C 100

0

0

10

20 time / min

30

(a) What is the melting point of the substance? ......................................................................................................................................[1] (b) What happens to the temperature while the substance changes state? ......................................................................................................................................[1] (c) Explain why the substance cannot be water. .......................................................................................................................................... ......................................................................................................................................[2]

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4 A3 Calcium oxide is produced by heating a mixture of limestone and coke in a lime kiln. CaCO3 (a) (i)

CaO + CO2

Explain the meaning of the symbol

.

................................................................................................................................... ................................................................................................................................... (ii)

In the lime kiln, the carbon dioxide is allowed to escape. Why does this increase the yield of calcium oxide? ................................................................................................................................... ................................................................................................................................... [2]

(b) The calcium oxide reacts with water to form slaked lime. (i)

Give the equation for this reaction. ...................................................................................................................................

(ii)

State a use of slaked lime. ................................................................................................................................... [2]

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For Examiner’s Use

For Examiner’s Use

5 A4 A student carried out two experiments. (a) In experiment 1, two gas jars were set up as shown.

air

glass disc

bromine gas

(i)

What was seen when the glass disc was removed? ................................................................................................................................... ...................................................................................................................................

(ii)

Explain why this change occurred. ................................................................................................................................... ................................................................................................................................... [3]

(b) The experiment was repeated, using the brown gas nitrogen dioxide, NO2. (i)

How would the rate of change be different from that observed in experiment 1? ...................................................................................................................................

(ii)

Why does this happen? ................................................................................................................................... ...............................................................................................................................[2]

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6 A5 Ethanoic acid is produced on an industrial scale by the oxidation of ethanol, C2H5OH. (a) Explain the meaning of the word oxidation. .......................................................................................................................................... ......................................................................................................................................[1] (b) Ethanol is a member of the homologous series of alcohols. (i)

State the name and draw the structure of the next alcohol in the series. name:......................................................................................................................... structure:

(ii)

Is the boiling point of this alcohol higher or lower than the boiling point of ethanol? Explain your answer. ................................................................................................................................... ................................................................................................................................... [3]

(c) (i)

Name the product formed when ethanoic acid reacts with ethanol. ...................................................................................................................................

(ii)

Write the equation for this reaction. ................................................................................................................................... [2]

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For Examiner’s Use

7 A6 Hydrogen bromide has a melting point of - 87 °C and a boiling point of - 67 °C. (a) In what state is hydrogen bromide at room temperature and pressure? ......................................................................................................................................[1] (b) Construct a ‘dot and cross’ diagram to show the bonding in hydrogen bromide. Your diagram only needs to show outer electrons.

[2] (c) Hydrogen bromide dissolves in water to form an acidic solution. (i)

Give the formula of the ion which causes the acidity. ...................................................................................................................................

(ii)

Describe what is seen when chlorine is bubbled through the solution. ................................................................................................................................... ...................................................................................................................................

(iii)

Construct an ionic equation for the reaction you have described in (ii). ................................................................................................................................... [4]

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8 A7 Ammonium nitrate, NH4NO3, and urea, CO(NH2)2, are both used in fertilisers. (a) Why is it important that fertilisers contain nitrogen? ......................................................................................................................................[1] (b) Ammonium nitrate is a ‘fast release’ fertiliser because it dissolves quickly in water. Explain, in terms of particles, what happens when solid ammonium nitrate dissolves in water. .......................................................................................................................................... .......................................................................................................................................... ......................................................................................................................................[2] (c) Urea contains 47% by mass of nitrogen. Show that 1 kg of urea contains more nitrogen than 1 kg of ammonium nitrate. .......................................................................................................................................... .......................................................................................................................................... ......................................................................................................................................[2]

A8 The diagram shows the Blast Furnace. iron ore, coke, raw material A waste gases

waste gases

hot air

hot air

molten slag molten iron

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For Examiner’s Use

For Examiner’s Use

9 (a) (i)

Name raw material A. ...................................................................................................................................

(ii)

Explain why A is added to the Blast Furnace. ................................................................................................................................... ................................................................................................................................... [2]

(b) (i)

Name the gaseous reducing agent in the furnace. ...................................................................................................................................

(ii)

Construct an equation for a reaction in which it is produced. ................................................................................................................................... [2]

(c) The iron produced by the Blast Furnace is converted into alloys. Explain what is meant by an alloy. .......................................................................................................................................... ......................................................................................................................................[1] (d) Most car bodies are made from mild steel. Some are made from aluminium alloys. Explain one disadvantage of each of these alloys for this purpose. mild steel .......................................................................................................................... .......................................................................................................................................... aluminium alloy ................................................................................................................ ......................................................................................................................................[2]

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10 Section B Answer three questions from this section. Write your answers on the lined pages that follow.

B9 Paraffin is a mixture of alkanes. In a laboratory experiment, paraffin was heated and passed over strongly heated broken pot, using the apparatus shown. broken pot ceramic wool soaked in paraffin gaseous hydrocarbons heat water

(a) (i) (ii)

Name the type of reaction which occurs in the apparatus. What is the purpose of the broken pot? [2]

(b) Propane can be decomposed by heat, forming ethene and one other product. (i)

Construct an equation for this reaction and describe the test which would show that an unsaturated compound had been formed.

(ii)

Calculate the maximum volume of ethene which is formed from 100 cm3 propane, all volumes measured at room temperature and pressure. [4]

(c) The structure of propene is shown below. H

H

H

C

C

C

H

H

H

Propene can be polymerised. (i)

Name the polymer formed.

(ii)

Name the type of polymerisation which takes place during this reaction, and draw the structure of the polymer which is formed.

(iii)

This polymer is non-biodegradable. Explain the term non-biodegradable. [4] 5070/2 W99

11 B10 (a) Butane is a fuel used in portable heaters. For the complete combustion of one mole of butane, ∆H = - 2880 kJ. (i)

Construct an equation for the complete combustion of butane.

(ii)

Calculate the quantity of heat evolved from the combustion of 16 dm3 of butane, measured at room temperature and pressure.

(iii)

Explain why the value of ∆H shows that the reaction is exothermic. [5]

(b) When silver chloride is exposed to light, a redox reaction occurs. The solid turns grey in colour. (i)

Explain why the solid turns grey.

(ii)

Explain why this is an example of a redox reaction.

(iii)

State a use of silver chloride which depends on this reaction. [5]

B11 This diagram shows an electrolysis tank used industrially to produce aluminium from aluminium oxide. Pure aluminium oxide melts at 2045 °C. +

graphite anodes

– steel tank

molten aluminium oxide and cryolite at 950 °C

graphite cathode molten aluminium out (a) State and explain why the cryolite is added to the aluminium oxide.

[2]

(b) Construct ionic equations for the reactions which take place at the electrodes.

[2]

(c) Explain why the carbon anodes need replacing regularly.

[2]

(d) Electrolysis is also used to purify copper. (i)

Draw and label a diagram of apparatus which could be used to purify a block of impure copper.

(ii)

Describe what happens at each electrode during the electrolysis. [4]

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12 B12 This flow chart represents part of the manufacture of sulphuric acid. air other gases oxygen 450 °C

sulphur trioxide

catalyst sulphur dioxide (a) Name the process used to separate the oxygen from liquid air and state the physical property on which it depends. [2] (b) (i)

Name the catalyst.

(ii)

Calculate the maximum mass of sulphur trioxide which could be produced from 3.2 kg of sulphur dioxide.

(iii)

Describe how the sulphur trioxide is converted into sulphuric acid. [5]

(c) Sulphur dioxide is an industrial pollutant. (i)

State two effects of sulphur dioxide on the environment.

(ii)

The combustion of coal in power stations produces waste gases containing sulphur dioxide. The sulphur dioxide can be removed by reaction with powdered limestone. State the type of reaction which occurs between sulphur dioxide and the limestone. [3]

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Magnesium

Sodium

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Strontium

45

Key

b

a

X

*

89

227

Actinium

Ac

b = proton (atomic) number

X = atomic symbol

a = relative atomic mass

†

72

Hafnium

Lanthanum

57

178

Hf

40

Zirconium

Zr

91

Titanium

139

Yttrium

Y

89

22

48

Ti

La

39

21

Scandium

Sc

*58-71 Lanthanoid series †90-103 Actinoid series

88

Radium

87

Francium

226

Ra

56

Barium

Caesium

Fr

55

137

Ba

133

Cs

38

Rubidium

37

88

Sr

85

Calcium

Rb

19

20

40

Ca

39

K

12

24

Mg

23

Na

Beryllium

4

Lithium

Potassium

11

3

9

Be

7

II

Li

I

93

Ta

181

Niobium

Nb

90

58

73

52

96

Mo

W

184

Protactinium

Thorium

55

Tc 186

Re

144

Nd

92

60

Uranium

U

238

Neodymium

75

Rhenium

43

Technetium

25

Manganese

Mn 27

59

28

59

29

64

30

65

5

Ru

101

Iron

190

Pm

Osmium

Os

Np 93

Neptunium

61

Promethium

76

44

Ruthenium

26

56

Fe

150

Sm

Pu 94

Plutonium

62

152

Eu

Am 95

Americium

63

Europium

78

Platinum

Pt

Iridium

195

Ir

46

Palladium

Pd

106

Nickel

Ni

192

Samarium

77

45

Rhodium

Rh

103

Cobalt

Co

Gd

157

Gold

Au

197

Silver

96

64

Curium

Cm

Gadolinium

79

47

Ag

108

Copper

Cu

201

Bk

Terbium

Tb

159

Mercury

Hg

97

Berkelium

65

80

48

Cadmium

Cd

112

Zinc

Zn

11

6

Dy

162

Thallium

Tl

204

Indium

Cf 98

Californium

66

Es

Holmium

Ho

165

Lead

Pb

207

Tin

99

Einsteinium

67

82

50

119

Sn

115

32

Germanium

Ge

73

Silicon

In

Gallium

Dysprosium

81

49

31

70

Ga

14

28

Si

Carbon

27

Aluminium

13

12

C

Al

Boron

B 7

14

75

Sb

122

Arsenic

As

Bi

209

Fermium

Fm

Erbium

Er

167

Bismuth

100

68

83

51

Antimony

33

15

Phosphorus

P

31

Nitrogen

N 8

Se

79

Sulphur

S

32

Oxygen

Po

169

Md

Thulium

Tm

101

Mendelevium

69

84

Polonium

52

Tellurium

Te

128

Selenium

34

16

16

O 9

Yb

173

Astatine

At

Iodine

I

127

Bromine

Br

80

Chlorine

No 102

Nobelium

70

Ytterbium

85

53

35

17

Cl

35.5

Fluorine

F

19

Lr

Lutetium

Lu

175

Radon

Rn

Xenon

Xe

131

Krypton

Kr

84

Argon

Ar

40

Neon

103

Lawrencium

71

86

54

36

18

10

Ne

20

Helium

2

0

Hydrogen

VII

4

VI

He

V

1

IV

H

III

The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.).

91

Pa

Th

232

Praseodymium

Cerium

59

141

Pr

140

74

Tungsten

42

Molybdenum

24

Chromium

Cr

Ce

Tantalum

41

23

Vanadium

V

51

1

Group

DATA SHEET The Periodic Table of the Elements

16