Chemstry June 2001 - Paper 2

Centre Number

Candidate Number

Candidate Name

UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS SYNDICATE General Certificate of Education Ordinary Level

5070/2

CHEMISTRY PAPER 2 Theory

MAY/JUNE SESSION 2001

1 hour 30 minutes

Additional materials: Answer paper

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 separate answer paper. At the end of the examination, fasten any separate answer paper used 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. FOR EXAMINER’S USE Section A B9 B10 B11 B12 TOTAL

This question paper consists of 13 printed pages and 3 blank pages. SB (SLC/JB) QF10457/1 © UCLES 2001

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For Examiner’s Use

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

A1 Choose from the following metals to answer the questions below. aluminium

calcium

copper

iron

magnesium

potassium

sodium

zinc

Each metal can be used once, more than once, or not at all. Name a metal which (a) is manufactured by the electrolysis of its molten oxide, ......................................................................................................................................[1] (b) has a variable valency, ......................................................................................................................................[1] (c) is used to galvanise iron, ......................................................................................................................................[1] (d) has a carbonate which is coloured, ......................................................................................................................................[1] (e) is alloyed with zinc to make brass. ......................................................................................................................................[1]

A2 A precipitate may be formed when two aqueous solutions are mixed. Complete the following table. solutions mixed together

formula of precipitate formed

colour of precipitate formed

copper(II) sulphate and sodium hydroxide sodium chloride and silver nitrate potassium iodide and lead(II) nitrate dilute sulphuric acid and barium chloride

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3 A3 (a) The table shows some information about the oxides of the elements A to E. The letters are not the symbols of the elements. element

state of oxide at room temperature and pressure

type of oxide

bonding in oxide

A

solid

basic

ionic

B

solid

acidic

covalent

C

gas

acidic

covalent

D

liquid

neutral

covalent

E

gas

neutral

covalent

For Examiner’s Use

Which one of the elements A to E could be (i)

hydrogen, ...............................................................................................................................[1]

(ii)

sodium, ...............................................................................................................................[1]

(iii)

silicon? ...............................................................................................................................[1]

(b) State the name of an element which forms an amphoteric oxide. ......................................................................................................................................[1]

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4 A4 Helium-6 and helium-7 are isotopes. The nucleon (mass) number of helium-6 is 6 and of helium-7 is 7. (a) What is the meaning of the term isotopes ? .......................................................................................................................................... .......................................................................................................................................... ......................................................................................................................................[1] (b) Compare the number of electrons, neutrons and protons in one atom of helium-6 and one atom of helium-7. (i)

electrons ...................................................................................................................

(ii)

protons ......................................................................................................................

(iii)

neutrons .................................................................................................................... ...............................................................................................................................[3]

(c) Explain why helium does not react with other elements to form compounds. .......................................................................................................................................... ......................................................................................................................................[1]

A5 Aqueous copper(II) sulphate reacts with aqueous potassium iodide according to the equation below. 2Cu2+(aq) + 4I–(aq) → 2CuI(s) + I2(s) (a) Identify the reducing agent in this reaction. Explain your answer. .......................................................................................................................................... ......................................................................................................................................[2] (b) Describe briefly how acidified potassium manganate(VII) can be used to test for a reducing agent. .......................................................................................................................................... ......................................................................................................................................[1]

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For Examiner’s Use

For Examiner’s Use

5 A6 Magnesium reacts with chlorine to form the ionic compound magnesium chloride. (a) Draw a ‘dot and cross’ diagram to show the bonding in magnesium chloride. You only need to draw the outer (valence) electrons of magnesium and of chlorine.

[2] (b) The physical properties of a compound are related to its structure and bonding. Magnesium chloride has an ionic lattice structure. Suggest two physical properties of magnesium chloride. 1. ...................................................................................................................................... 2. ..................................................................................................................................[2]

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For Examiner’s Use

6 A7 A student investigates the reaction between zinc and dilute hydrochloric acid. The student uses the apparatus shown in the diagram. measuring cylinder

small test-tube held by a piece of cotton

zinc powder water

hydrochloric acid

To start the reaction the student tips the flask so that the acid and zinc can mix. Every minute the student measures the volume of gas collected. The results are plotted on the graph below.

500

400 total volume 300 of hydrogen / cm3 200

100

0 0

2

4

6 time / minutes 5070/2 Jun01

8

10

12

For Examiner’s Use

7 (a) Write the equation for the reaction between zinc and dilute hydrochloric acid. ......................................................................................................................................[1] (b) A sample of 0.65 g of zinc and 50 cm3 of 2.0 mol/dm3 hydrochloric acid is used. Which reagent, zinc or hydrochloric acid, is in excess at the end of the reaction? Explain your answer.

[3] (c) The rate of reaction changes as the reaction proceeds. How and why does the rate of reaction change? .......................................................................................................................................... .......................................................................................................................................... ......................................................................................................................................[2] (d) The investigation is repeated using exactly the same amounts of zinc and dilute hydrochloric acid. The only difference is that warm hydrochloric acid is used rather than cold hydrochloric acid. On the grid, sketch the graph of the results you would expect. [1]

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8 A8 The table shows some information about compounds in a homologous series. name of compound

molecular formula

relative molecular mass

methanol

CH3OH

32

65

ethanol

C2H5OH

46

78

propan-1-ol

C3H7OH

60

97

butan-1-ol

C4H9OH

74

117

pentan-1-ol

C5H11OH

88

138

(a) (i)

boiling point / °C

Name the homologous series to which these compounds belong. ...............................................................................................................................[1]

(ii)

Predict the relative molecular mass of the compound, in the same series, which has seven carbon atoms in one molecule. ...............................................................................................................................[1]

(iii)

Predict the boiling point of hexan-1-ol, which has six carbon atoms in one molecule. ...............................................................................................................................[1]

(iv)

Write the general formula for a compound in this homologous series. ...............................................................................................................................[1]

(b) State a use for ethanol, other than in drinks. ......................................................................................................................................[1]

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For Examiner’s Use

For Examiner’s Use

9 (c) Ethanol can be oxidised to form ethanoic acid. (i)

Draw the structure of ethanoic acid.

(ii)

Name a reagent that can be used to oxidise ethanol to ethanoic acid. ...................................................................................................................................

(iii)

Give the name and the structure of the organic product formed when ethanol and ethanoic acid react with each other. name of product ........................................................................................................ structure of product

[4]

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10 Section B Answer three questions from this section. The total mark for this section is 30.

B9 Petrol and diesel are liquid fuels used in the internal combustion engines of motor cars and lorries. (a) Describe how petrol and diesel are obtained from petroleum (crude oil).

[3]

(b) The exhaust gas from an internal combustion engine contains pollutants. The table below shows the mass of pollutants formed when one kilogram of each fuel is burnt. mass of pollutant / g fuel

carbon monoxide

oxides of nitrogen

sulphur dioxide

volatile organic compounds e.g. unburnt hydrocarbons

petrol

236

29

0.9

25

0.6

diesel

10

59

3.8

17

18.6

particulates

(i)

Which pollutant is a poisonous gas formed by the incomplete combustion of the fuels?

(ii)

Which fuel contributes the most towards acid rain for each kilogram burnt? Explain your answer.

(iii)

Nitrogen dioxide is formed when oxygen reacts with nitrogen. Write the equation for this reaction.

(iv)

Many cars are fitted with catalytic converters. In the catalytic converter carbon monoxide is oxidised and nitrogen dioxide is reduced to form two harmless gases. Suggest the names of these two gases. [5]

(c) Octane, C8H18, is a hydrocarbon found in petrol. Complete combustion of one mole of octane releases 5518 kilojoules of energy. Calculate the energy released on complete combustion of 1.14 g of octane.

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[2]

11 B10 Ethanol is manufactured by the reversible reaction between ethene and steam. C2H4(g) + H2O(g)

CH3CH2OH(g)

The position of equilibrium is affected by changes in pressure and temperature. In an experiment, one mole of ethene was allowed to react with excess steam. The table shows the amount of ethanol in the equilibrium mixture under five different sets of conditions.

(a) (i) (ii)

temperature/ °C

pressure/ atm

amount of ethanol at equilibrium/mol

300 300 300 250 350

50 60 70 50 50

0.40 0.46 0.55 0.42 0.38

Describe the effect of increasing the pressure on the amount of ethanol at equilibrium. Is the reaction between ethene and steam endothermic or exothermic? Explain your answer.

(iii)

Which set of conditions (temperature and pressure) will give the lowest rate of reaction? [4]

(b) Ethene also reacts with hydrogen and bromine. (i)

Name the product of the reaction between ethene and hydrogen.

(ii)

Draw the structure of the product of the reaction between ethene and bromine. [2]

(c) Ethene forms an addition polymer called poly(ethene). The polymer is used to make plastic bags. Draw the structure of and describe a pollution problem caused by poly(ethene).

[2]

(d) Draw a ‘dot and cross’ diagram to show the bonding in a molecule of ethene. You only need to draw the outer electrons of carbon and of hydrogen.

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[2]

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12 B11 There are four stages in the conversion of sulphur into sulphuric acid. • • • •

Stage 1 – Sulphur is burned to make sulphur dioxide. Stage 2 – Sulphur dioxide is oxidised to sulphur trioxide (the Contact Process). Stage 3 – Sulphur trioxide is dissolved in sulphuric acid to form oleum. Stage 4 – Oleum is diluted with water to form concentrated sulphuric acid.

(a) State the catalyst and give the equation for stage 2 (the Contact Process).

[3]

(b) Calculate the mass of sulphur needed to make 196 kg of sulphuric acid.

[3]

(c) Give two uses of sulphuric acid.

[2]

(d) Describe what you would see and name the products formed when dilute sulphuric acid reacts with magnesium carbonate. [2]

B12 Chlorine, bromine and iodine are elements in Group VII of the Periodic Table. (a) Describe the trend in colour and physical state at room temperature and pressure as the atomic number increases. [2] (b) Aqueous chlorine is an oxidising agent. (i)

Name the products formed and write an ionic equation for the reaction between aqueous chlorine and aqueous potassium bromide.

(ii)

Name the product formed when aqueous chlorine reacts with aqueous iron(II) chloride. [3]

(c) An oxide of chlorine was analysed. A 0.366 g sample was found to contain 0.224 g of oxygen. Calculate the empirical formula of this oxide.

[3]

(d) Chlorine (IV) oxide, ClO2, is a powerful oxidising agent. (i)

Construct an equation to show the decomposition of chlorine(IV) oxide into its elements.

(ii)

Chlorine(IV) oxide reacts explosively with powdered sulphur. Suggest the name or formula of one of the products of the reaction between sulphur and chlorine(IV) oxide. [2]

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13 BLANK PAGE

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14 BLANK PAGE

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15 BLANK PAGE

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Magnesium

Sodium

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Strontium

45

Key

b

X

a

*

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

Sm

150

Iridium

Pu 94

Plutonium

62

152

Eu

Am 95

Americium

63

Europium

78

Platinum

195

Pt

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