GCSE Chemistry Practice Paper 2

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Instructions to Students

Use black ink or black ball-point pen.
Fill in the boxes at the top of this page with your details if required.
Answer all questions in the spaces provided.
Do all rough work in this book. Cross through any work you do not want to be marked.
In all calculations, show clearly how you work out your answer.
A Periodic Table is provided as a separate insert if required.
Calculators may be used.

Information for Candidates

This practice paper is designed to support student revision for the GCSE Chemistry examinations. It contains questions covering atomic structure, bonding, quantitative chemistry, chemical changes, and energy changes. The marks for individual questions and parts of questions are shown in round brackets.

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Question 1 [4 Marks]

For many years, scientists accepted the plum pudding model of the atom before the nuclear model was proposed.

(4)

Compare the plum pudding model of the atom and the nuclear model. In your comparison, highlight both similarities and differences between the two models.

Question 2 [12 Marks]

The position of elements in the periodic table is determined by their atomic structure and electronic configuration.

(6)

(a) Magnesium has an atomic number of 12, and calcium has an atomic number of 20.
Write the electronic configurations of magnesium and calcium. Explain, in terms of subatomic particles and configuration, why both magnesium and calcium are placed in Group 2 of the periodic table.

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(6)

(b) Chlorine, bromine, and iodine are halogens in Group 7 of the periodic table.
Explain, in terms of electronic configurations and shielding, why the reactivity of these Group 7 elements decreases down the group.

Question 3 [6 Marks]

Silicon dioxide (SiO2) is a giant covalent structure found in quartz, while diamond is an allotrope of carbon.

(6)

Compare the structure and bonding of silicon dioxide and diamond. Explain why both substances have high melting points and do not conduct electricity.

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Question 4 [6 Marks]

Water (H2O) is a simple molecular compound that is essential for life.

(4)

(a) Draw a dot-and-cross diagram to show the covalent bonding in a water molecule (H2O). You only need to show the outer shell electrons. Explain how the covalent bonds are formed in terms of electrostatic attractions.

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(2)

(b) Explain, in terms of structure and bonding, why water has a relatively low boiling point (100 °C) compared to magnesium oxide, even though the covalent bonds within the water molecule are very strong.

Question 5 [6 Marks]

A student is given a table containing physical properties of three unidentified substances: A, B, and C.

Substance	Melting Point / °C	Boiling Point / °C	Electrical Conductivity as Solid	Electrical Conductivity as Liquid	Solubility in Water
Substance A	1083	2562	Conducts	Conducts	Insoluble
Substance B	1713	2950	Does not conduct	Does not conduct	Insoluble
Substance C	601	1420	Does not conduct	Conducts	Soluble

The student claims that Substance A is giant covalent, Substance B is simple molecular, and Substance C is giant ionic.

(6)

Evaluate the student's claims. For each substance, state whether the claim is correct or incorrect, and explain your reasoning by analyzing the data in the table.

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Question 6 [4 Marks]

(4)

Explain metallic bonding in metals. Describe how this type of bonding explains why metals can conduct electricity and why they are malleable.

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Question 7 [8 Marks]

A student performs paper chromatography to separate a mixture of food dyes:

(3)

(a) Explain how paper chromatography separates different components in a mixture. You must refer to the mobile and stationary phases in your response.

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This resource is an independent educational tool created to support student revision. It is completely independent and is not endorsed by, affiliated with, or sponsored by any official examination board. All trademarked terms are used under Nominative Fair Use purely for descriptive compatibility indexing. Licensed for individual personal use only.
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(1)

(b) State why the starting line on a chromatogram must be drawn in pencil rather than ink.

(4)

(c) Using the distances shown in the chromatogram on Page 7, calculate the Rf values for Dye A and Dye B. Show your working.

Question 8 [5 Marks]

Lithium reacts vigorously with water to form lithium hydroxide and hydrogen gas according to the equation:

2Li(s) + 2H2O(l) → 2LiOH(aq) + H2(g)

A student reacts 3.50 g of lithium metal with 18.0 g of water.

(5)

Show by calculation which reactant is the limiting reactant, and calculate the maximum theoretical mass of lithium hydroxide (LiOH) in grams that can be produced.
Relative atomic masses (Ar): H = 1.0; O = 16.0; Li = 7.0

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Question 9 [2 Marks]

(2)

After completing the reaction from Question 8, the student filters and evaporates the solution. The actual yield of dry lithium hydroxide obtained is 9.00 g.
Calculate the percentage yield of lithium hydroxide. Show your working.

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Question 10 [4 Marks]

(4)

Using the quantities from Question 8, calculate the volume of hydrogen gas (H2) produced in dm3 at room temperature and pressure (RTP).
Assume 1 mole of any gas occupies 24.0 dm3 at RTP.
Relative atomic masses (Ar): H = 1.0; O = 16.0; Li = 7.0

Question 11 [6 Marks]

Barium hydroxide solution reacts with nitric acid according to the equation:

Ba(OH)2(aq) + 2HNO3(aq) → Ba(NO3)2(aq) + 2H2O(l)

A student titrates 20.0 cm3 of barium hydroxide (Ba(OH)2) solution against a standard nitric acid (HNO3) solution.

(6)

The student finds that exactly 25.0 cm3 of 0.050 mol/dm3 nitric acid is required to completely neutralise the 20.0 cm3 sample of barium hydroxide.
Calculate the concentration of the barium hydroxide solution in mol/dm3 and in g/dm3. Give your answer to 3 significant figures.
Relative atomic masses (Ar): H = 1.0; N = 14.0; O = 16.0; Ba = 137.0

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Question 12 [10 Marks]

A student carries out the electrolysis of aqueous potassium bromide (KBr) using inert carbon electrodes.

(2)

(a) State all four chemical ions that are present in an aqueous solution of potassium bromide.

(4)

(b) Identify the product formed at the positive electrode (anode), write a half-equation for this process, and explain why this product forms preferentially to any other potential products.

(4)

(c) Identify the product formed at the negative electrode (cathode), write a half-equation for this process, and explain why this product forms preferentially to any other potential products.

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Question 13 [4 Marks]

(4)

A solution of hydrochloric acid (HCl) is diluted, causing its pH to increase from 1.0 to 3.0. Show by calculation and explanation how this change in pH is related to the hydrogen ion concentration, [H+], in the solution. You must include a base-10 logarithmic relationship in your proof.

Question 14 [9 Marks]

A student investigates the temperature change during a displacement reaction. They add varying masses of zinc powder to 25.0 cm3 of 0.50 mol/dm3 copper(II) sulfate (CuSO4) solution in a polystyrene cup.

(2)

(a) Explain why a polystyrene cup is used rather than a glass beaker to perform this experiment.

(2)

(b) Write the ionic equation for the displacement reaction that occurs between zinc and copper(II) ions. You must include state symbols.

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(3)

(c) Explain why the temperature of the reaction mixture increases when zinc is first added, and explain why the temperature eventually stops rising as more zinc is added.

(2)

(d) Write the half-equation to show the oxidation of zinc atoms during the displacement reaction.

Question 15 [8 Marks]

Thermal decomposition of calcium carbonate is a chemical process represented by the equation:

CaCO3(s) → CaO(s) + CO2(g)

The energy changes of this reaction are shown on the energy profile diagram below.

(1)

(a) State what is meant by an endothermic reaction in terms of energy exchange with the surroundings.

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(4)

(b) Identify the labels on the energy profile diagram below. Specify the chemical species or terms representing labels: W, X, Y, and Z.

(3)

(c) Explain the thermal decomposition of calcium carbonate as an endothermic reaction in terms of bond breaking and bond making.

Question 16 [6 Marks]

Hydrogen gas reacts with bromine vapour to produce hydrogen bromide gas according to the equation:

H2(g) + Br2(g) → 2HBr(g)

(3)

(a) Calculate the overall enthalpy change (ΔH) in kJ/mol for this reaction using the following bond energies:
H-H = 436 kJ/mol; Br-Br = 193 kJ/mol; H-Br = 366 kJ/mol

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(3)

(b) Explain, in terms of bond breaking and bond making, why the reaction of hydrogen and bromine is exothermic.

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Group 1

Group 2

Transition Metals

Group 3

Group 4

Group 5

Group 6

Group 7

Group 0

KEY

relative atomic mass

H

atomic symbol

name

atomic (proton) number

* Lanthanides

** Actinides

1 H Hydrogen 1

4 He Helium 2

7 Li Lithium 3

9 Be Beryllium 4

11 B Boron 5

12 C Carbon 6

14 N Nitrogen 7

16 O Oxygen 8

19 F Fluorine 9

20 Ne Neon 10

23 Na Sodium 11

24 Mg Magnesium 12

27 Al Aluminium 13

28 Si Silicon 14

31 P Phosphorus 15

32 S Sulfur 16

35.5 Cl Chlorine 17

40 Ar Argon 18

39 K Potassium 19

40 Ca Calcium 20

45 Sc Scandium 21

48 Ti Titanium 22

51 V Vanadium 23

52 Cr Chromium 24

55 Mn Manganese 25

56 Fe Iron 26

59 Co Cobalt 27

59 Ni Nickel 28

63.5 Cu Copper 29

65 Zn Zinc 30

70 Ga Gallium 31

73 Ge Germanium 32

75 As Arsenic 33

79 Se Selenium 34

80 Br Bromine 35

84 Kr Krypton 36

85.5 Rb Rubidium 37

88 Sr Strontium 38

89 Y Yttrium 39

91 Zr Zirconium 40

93 Nb Niobium 41

96 Mo Molybdenum 42

98 Tc Technetium 43

101 Ru Ruthenium 44

103 Rh Rhodium 45

106 Pd Palladium 46

108 Ag Silver 47

112 Cd Cadmium 48

115 In Indium 49

119 Sn Tin 50

122 Sb Antimony 51

128 Te Tellurium 52

127 I Iodine 53

131 Xe Xenon 54

133 Cs Cesium 55

137 Ba Barium 56

139 La* Lanthanum 57

178.5 Hf Hafnium 72

181 Ta Tantalum 73

184 W Tungsten 74

186 Re Rhenium 75

190 Os Osmium 76

192 Ir Iridium 77

195 Pt Platinum 78

197 Au Gold 79

201 Hg Mercury 80

204 Tl Thallium 81

207 Pb Lead 82

209 Bi Bismuth 83

209 Po Polonium 84

210 At Astatine 85

222 Rn Radon 86

223 Fr Francium 87

226 Ra Radium 88

227 Ac** Actinium 89

267 Rf Rutherfordium 104

268 Db Dubnium 105

269 Sg Seaborgium 106

270 Bh Bohrium 107

269 Hs Hassium 108

278 Mt Meitnerium 109

281 Ds Darmstadtium 110

282 Rg Roentgenium 111

285 Cn Copernicium 112

286 Nh Nihonium 113

289 Fl Flerovium 114

289 Mc Moscovium 115

293 Lv Livermorium 116

294 Ts Tennessine 117

294 Og Oganesson 118

140 Ce Cerium 58

141 Pr Praseodymium 59

144 Nd Neodymium 60

145 Pm Promethium 61

150 Sm Samarium 62

152 Eu Europium 63

157 Gd Gadolinium 64

159 Tb Terbium 65

162.5 Dy Dysprosium 66

165 Ho Holmium 67

167 Er Erbium 68

169 Tm Thulium 69

173 Yb Ytterbium 70

175 Lu Lutetium 71

232 Th Thorium 90

231 Pa Protactinium 91

238 U Uranium 92

237 Np Neptunium 93

244 Pu Plutonium 94

243 Am Americium 95

247 Cm Curium 96

247 Bk Berkelium 97

251 Cf Californium 98

252 Es Einsteinium 99

257 Fm Fermium 100

258 Md Mendelevium 101

259 No Nobelium 102

266 Lr Lawrencium 103

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