0620 Chemistry June 2025 Question Paper 41

1 A list of substances is shown. bauxite calcium oxide ethanol graphite methane nitrogen oxygen propane propene sulfur dioxide

Answer the questions using the list of substances.

Each substance may be used once, more than once, or not at all.

State which of the substances:

(a) is a basic oxide [1]

(b) contains carbon atoms only [1]

(c) is manufactured by fermentation [1]

(d) is produced by the decomposition of vegetation [1]

(e) contains aluminium oxide [1]

(f) causes acid rain [1]

(g) is a simple molecule with 11 atoms [1]

(h) is produced when limestone thermally decomposes in the blast furnace [1]

(i) is a gas that is approximately 21% of clean, dry air [1]

(j) is a monomer in addition polymerisation [1]

[Total: 10] , ,

2 Atoms are made of electrons, neutrons and protons.

(a) Complete Table 2.1. Table 2.1 particle relative charge relative mass electron 1 1840 neutron 0 proton

[2]

(b) Atoms of the same element are known as isotopes.

39 19K and 41 19K are isotopes of potassium.

(i) Complete Table 2.2 to show the number of electrons, neutrons and protons in one atom or ion of these isotopes. Table 2.2 isotope electrons neutrons protons 39 19K 41 19K+

[3]

(ii) Table 2.3 shows the relative masses and the percentage abundances of the two isotopes in a sample of potassium. Table 2.3 relative mass of isotope percentage abundance of isotope 39 90 41 10

Calculate the relative atomic mass of this sample of potassium to one decimal place. relative atomic mass = [2] , ,

(iii) An isotope of aluminium has a nucleon number of 27.

Aluminium has a relative atomic mass of 27.

State what conclusion can be made from this information [1]

(c) A calcium atom has the electronic configuration of 2,8,8,2.

Give the formula of one atom and one negative ion that has the same electronic configuration as Ca2+. • atom • negative ion [2]

[Total: 10] , ,

3 This question is about copper and compounds of copper.

(a) (i) Describe the bonding in a metallic element such as copper [3]

(ii) Explain how solid copper conducts electricity [1]

(b) Copper is in alloys such as brass.

(i) State one reason why alloys are more useful than pure metals [1]

(ii) Name the substance that is present in brass, other than copper [1]

(c) Copper(II) sulfate crystals are made by the reaction between copper(II) carbonate and dilute sulfuric acid, using the following steps.

The sulfuric acid has a concentration of 0.100 mol / dm3.

step 1 Powdered copper(II) carbonate is added to dilute sulfuric acid. The mixture is stirred. A reaction occurs.

step 2 More copper(II) carbonate is added, with stirring, until the reaction stops.

step 3 Unreacted copper(II) carbonate is separated from aqueous copper(II) sulfate by filtration.

step 4 Aqueous copper(II) sulfate is heated until some of the water evaporates.

step 5 The remaining solution is allowed to cool and crystallise.

step 6 The crystals are removed and dried.

(i) Give two observations in step 1. 1 2 [2] , ,

(ii) State why the reaction stops in step 2 [1]

(iii) Name the residue in step 3 [1]

(iv) Name a substance, other than copper(II) carbonate, that can be added to dilute sulfuric acid to produce aqueous copper(II) sulfate [1]

(v) The solution at the end of step 4 contains the maximum amount of copper(II) sulfate that will dissolve at that temperature.

State the term used to describe this type of solution [1]

(vi) Step 1 is repeated using sulfuric acid of concentration 0.200 mol / dm3 instead of 0.100 mol / dm3.

All other conditions are the same.

The rate of reaction increases.

Explain why the rate of reaction increases. Give your answer in terms of particles [2]

(vii) Copper(II) sulfate crystals have the formula CuSO4•5H2O.

State the term used to describe a substance that is chemically combined with water [1]

[Total: 15] , ,

4 This question is about nitrogen and its compounds.

Nitrogen contains molecules with the formula N2.

(a) Complete the dot-and-cross diagram in Fig. 4.1 to show the electronic configuration in a nitrogen molecule. Show outer-shell electrons only. N N Fig. 4.1

[2]

(b) Ammonia, NH3, is manufactured by reacting nitrogen with hydrogen, H2, in the Haber process.

(i) State three typical conditions for the reaction between nitrogen and hydrogen in the Haber process. 1 2 3 [3]

(ii) Write the symbol equation for the chemical reaction in the Haber process [1]

(c) Ammonia is converted into nitric acid in a two-step process.

In step 1, ammonia and oxygen are passed over a catalyst.

(i) Balance the symbol equation for this reaction. 4NH3 + …..O2 …..NO + .….H2O

[1]

(ii) Give the oxidation number of nitrogen in: • NH3 • NO [2] , ,

(iii) Define oxidation in terms of oxidation number [1]

(iv) In step 2, oxygen and water react with NO to produce nitric acid as the only product.

Write a symbol equation for this chemical reaction [2]

(d) Ammonia is converted into ammonium sulfate, (NH4)2SO4. 2NH3(g) + H2SO4(aq) (NH4)2SO4(s)

360 dm3 of ammonia gas, measured at r.t.p., reacts with excess sulfuric acid.

Calculate the mass of ammonium sulfate produced, using the following steps. • Calculate the number of moles of NH3(g) in 360 dm3.

One mole of any gas occupies 24 dm3 at r.t.p mol • Calculate the number of moles of (NH4)2SO4 produced mol • Calculate the mass of (NH4)2SO4 produced.

The Mr of (NH4)2SO4 is 132 g

[3]

[Total: 15] , ,

5 Methanol, CH3OH, is manufactured by the reaction between hydrogen and carbon monoxide.

An equilibrium mixture is produced. 2H2(g) + CO(g) CH3OH(g)

(a) State what happens to the concentration of CH3OH when the reaction is at equilibrium.

Explain your answer in terms of rate of forward and reverse reactions [2]

(b) The reaction is carried out at a pressure of 75 atmospheres and a temperature of 250 °C.

(i) State two disadvantages of using a pressure below 75 atmospheres. 1 2 [2]

(ii) Complete Table 5.1 using only the words increases, decreases or no change. Table 5.1 effect on the concentration of CH3OH(g) at equilibrium effect on the rate of the reverse reaction catalyst is added

[2]

(iii) If a temperature of more than 250 °C is used, the yield of methanol decreases.

State what can be deduced about the forward reaction [1]

(iv) Suggest which of the elements from the list is a suitable catalyst for the reaction. Give a reason for your answer. barium carbon copper potassium sulfur catalyst reason [2] , ,

(c) Methanol is a member of the homologous series of alcohols.

(i) State two characteristics of all members of a homologous series. 1 2 [2]

(ii) State the molecular formula of an alcohol that contains five carbon atoms [1]

(d) Carboxylic acids react with alcohols to form esters.

(i) Draw the displayed formula of an ester which contains three carbon atoms.

[2]

(ii) Butyl ethanoate is an ester.

Name the alcohol and the carboxylic acid that react to produce butyl ethanoate. alcohol carboxylic acid [2]

(e) An organic compound has the following composition by mass:

C, 64.87%; H, 13.51%; O, 21.62%.

Calculate the empirical formula of the compound.

empirical formula = [2]

[Total: 18] , ,

6 This question is about the Periodic Table.

(a) State the name given to Group VII elements [1]

(b) State which Group VII element is most reactive [1]

(c) Give the physical state and colour of iodine at room temperature and pressure. state colour [2]

(d) When bromine is added to aqueous potassium iodide a displacement reaction occurs.

The equation for the reaction is shown. Br2 + 2KI 2KBr + I2

(i) Write an ionic equation for the reaction [2] , ,

(ii) Iodine and bromine react at high temperatures to form iodine monobromide, IBr.

The equation is shown. I2(g) + Br2(g) 2IBr(g)

The structures of the molecules involved in the reaction are I–I, Br–Br and I–Br. Table 6.1 bond bond energy in kJ / mol I–I 150 Br–Br 193 I–Br 175

Calculate the enthalpy change, ΔH, for the reaction using the bond energies in Table 6.1.

Use the following steps. • Calculate the total amount of energy required to break the bonds in 1 mol of I2(g) and 1 mol of Br2(g) kJ • Calculate the total amount of energy released when the bonds in 2 mol of IBr(g) are formed kJ • Calculate the enthalpy change, ΔH, for the reaction.

Your answer should include a sign kJ / mol

[3] , ,

(e) Sodium is in Group I of the Periodic Table.

When sodium is added to water a chemical reaction occurs.

(i) Give two observations when sodium is added to water. 1 2 [2]

(ii) Thymolphthalein is added to the solution when the reaction has finished.

State the final colour of the thymolphthalein in the solution [1]

[Total: 12] , , Group The Periodic Table of Elements 1 H hydrogen 1 2 He helium 4 I II III IV V VI VII VIII 3 Li lithium 7 4 Be beryllium 9 atomic number atomic symbol Key name relative atomic mass 11 Na sodium 23 12 Mg magnesium 24 19 K potassium 39 20 Ca calcium 40 37 Rb rubidium 85 38 Sr strontium 88 55 Cs caesium 133 56 Ba barium 137 87 Fr francium – 88 Ra radium – 5 B boron 11 13 Al aluminium 27 31 Ga gallium 70 49 In indium 115 81 Tl thallium 204 113 Nh nihonium – 6 C carbon 12 14 Si silicon 28 32 Ge germanium 73 50 Sn tin 119 82 Pb lead 207 22 Ti titanium 48 40 Zr zirconium 91 72 Hf hafnium 178 104 Rf rutherfordium – 23 V vanadium 51 41 Nb niobium 93 73 Ta tantalum 181 105 Db dubnium – 24 Cr chromium 52 42 Mo molybdenum 96 74 W tungsten 184 106 Sg seaborgium – 25 Mn manganese 55 43 Tc technetium – 75 Re rhenium 186 107 Bh bohrium – 26 Fe iron 56 44 Ru ruthenium 101 76 Os osmium 190 108 Hs hassium – 27 Co cobalt 59 45 Rh rhodium 103 77 Ir iridium 192 109 Mt meitnerium – 28 Ni nickel 59 46 Pd palladium 106 78 Pt platinum 195 110 Ds darmstadtium – 29 Cu copper 64 47 Ag silver 108 79 Au gold 197 111 Rg roentgenium – 30 Zn zinc 65 48 Cd cadmium 112 80 Hg mercury 201 112 Cn copernicium – 114 Fl flerovium – 116 Lv livermorium – 7 N nitrogen 14 15 P phosphorus 31 33 As arsenic 75 51 Sb antimony 122 83 Bi bismuth 209 115 Mc moscovium – 8 O oxygen 16 16 S sulfur 32 34 Se selenium 79 52 Te tellurium 128 84 Po polonium – 9 F fluorine 19 17 Cl chlorine 35.5 35 Br bromine 80 53 I iodine 127 85 At astatine – 117 Ts tennessine – 10 Ne neon 20 18 Ar argon 40 36 Kr krypton 84 54 Xe xenon 131 86 Rn radon – 118 Og oganesson – 21 Sc scandium 45 39 Y yttrium 89 57–71 lanthanoids 89–103 actinoids 57 La lanthanum 139 89 Ac lanthanoids actinoids The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.). actinium – 58 Ce cerium 140 90 Th thorium 232 59 Pr praseodymium 141 91 Pa protactinium 231 60 Nd neodymium 144 92 U uranium 238 61 Pm promethium – 93 Np neptunium – 62 Sm samarium 150 94 Pu plutonium – 63 Eu europium 152 95 Am americium – 64 Gd gadolinium 157 96 Cm curium – 65 Tb terbium 159 97 Bk berkelium – 66 Dy dysprosium 163 98 Cf californium – 67 Ho holmium 165 99 Es einsteinium – 68 Er erbium 167 100 Fm fermium – 69 Tm thulium 169 101 Md mendelevium – 70 Yb ytterbium 173 102 No nobelium – 71 Lu lutetium 175 103 Lr lawrencium – , ,