Chemistry 0620/41 May/June 2024: question paper and mark scheme

Question

Name the process that is used to: (a) convert sulfur dioxide into sulfur trioxide in the manufacture of sulfuric acid . …… [1] (b) obtain water from aqueous sodium chloride . …… [1] (c) extract aluminium from purified bauxite . …… [1] (d) separate petroleum into useful substances . …… [1] (e) produce ethanol from aqueous glucose . …… [1] (f) manufacture alkenes and hydrogen from large alkane molecules . …… [1] (g) separate a mixture of soluble coloured substances. . …… [1] [Total: 7]

Question

Complete Table 2.1. Table 2.1 number of number of number of atom or ion protons electrons neutrons 17Cl 37 17 29Cu 63 + 34 16 18 17 [5]

Question

This question is about the elements sodium and fluorine and the compound sodium fluoride. (a) Sodium reacts with fluorine to form sodium fluoride. Write a symbol equation for this reaction. . …… [2] (b) Some properties of sodium, fluorine and sodium fluoride are shown in Table 3.1. Table 3.1 conduction of conduction of melting point boiling point electricity when electricity in / °C / °C solid aqueous solution sodium 98 883 good fluorine –220 –188 poor sodium fluoride 993 1695 poor good (i) Explain why sodium conducts electricity when it is a solid. . …… [1] (ii) Complete the dot-and-cross diagram in Fig. 3.1 of a molecule of fluorine. Show outer shell electrons only. F F Fig. 3.1 [2] (iii) Deduce the physical state of fluorine at –200 °C. Use the data in Table 3.1 to explain your answer. physical state . …… explanation …… . …… [2] (iv) Explain in terms of structure and bonding why sodium fluoride has a much higher melting point than fluorine. . …… . …… . …… . …… . …… [3] (c) Dilute aqueous sodium fluoride undergoes electrolysis. Hydrogen is produced at the cathode. (i) State what is meant by the term electrolysis. . …… . …… . …… [2] (ii) Write an ionic half-equation for the production of hydrogen at the cathode. . …… [2] [Total: 14]

Question

Hydrogen iodide thermally decomposes into iodine and hydrogen. The reaction is reversible. 2HI(g) I2(g) + H2(g) colourless gas purple gas colourless gas Fig. 4.1 shows a gas syringe containing a mixture of hydrogen iodide, iodine and hydrogen gases. The gas syringe is sealed and the mixture is heated to 300 °C. The mixture of gases reaches equilibrium and is purple. equilibrium mixture of hydrogen iodide, iodine and hydrogen end sealed plunger Fig. 4.1 (a) State what is meant by the term equilibrium. . …… . …… . …… [2] (b) The pressure of the mixture is increased. All other conditions stay the same. The position of equilibrium does not change. The colour of the gaseous mixture turns darker purple. The temperature remains constant. 2HI(g) I2(g) + H2(g) colourless gas purple gas colourless gas (i) Explain why the position of equilibrium does not change. . …… . …… [1] (ii) Suggest why the colour of the mixture of gases turns darker purple. . …… . …… [1] (c) The temperature of the mixture of gases is decreased. All other conditions stay the same. The mixture of gases turns lighter purple. State what can be deduced about the forward reaction from this information. . …… [1] (d) Deduce the oxidation number of iodine, I, in: HI …… I2. …… [2] (e) Methanol is manufactured by reacting carbon monoxide with hydrogen. CO(g) + 2H2(g) CH3OH(g) The rate of formation of methanol increases when a catalyst is used. (i) Choose from the list the element that is most likely to be used as the catalyst. Draw a circle around your chosen answer. calcium carbon copper sodium sulfur[1] (ii) State the effect on the position of equilibrium when a catalyst is used. . …… [1] (iii) State the effect that a catalyst has on the activation energy, Ea, of a reaction. . …… [1] [Total: 10]

Question

(a) Lead(II) bromide, PbBr2, is an insoluble salt and is made by precipitation. (i) Name two aqueous solutions that produce a precipitate of lead(II) bromide when they are mixed. 1 . …… 2 . …… [2] (ii) Describe how to produce a pure sample of lead(II) bromide from the mixture of aqueous solutions in (a)(i). . …… . …… [2] (iii) Write an ionic equation for the precipitation reaction which produces lead(II) bromide. Include state symbols. . …… [3] (b) When iron(II) sulfate crystals are heated strongly, sulfur dioxide gas is given off. Describe a test for sulfur dioxide gas. test . …… observations …… [2] (c) Complete the equation for the thermal decomposition of hydrated cobalt(II) nitrate. 2Co(NO3)2•4H2O → ....CoO + ....NO2 + O2 + ....H2O[2] (d) Hydrated cobalt(II) sulfate, CoSO4•xH2O, produces water when it is heated. CoSO4•xH2O(s) → CoSO4(s) + xH2O(g) A student does an experiment to determine the value of x in CoSO4•xH2O. step 1 The student weighs a sample of hydrated cobalt(II) sulfate. step 2 The student heats the sample of hydrated cobalt(II) sulfate. step 3 The student weighs the remaining solid after heating. (i) Describe what else the student should do to ensure that all the water has been given off. No other substances are required. . …… . …… . …… [2] (ii) In an experiment, 1.405 g of CoSO4•xH2O is heated until all the water is given off. The mass of CoSO4 that remains is 0.775 g. [Mr: CoSO4, 155; H2O, 18] Determine the value of x using the following steps. ● Calculate the number of moles of CoSO4 that remains. …… mol ● Calculate the mass of H2O given off. …… g ● Calculate the number of moles of H2O given off. …… mol ● Determine the value of x. x = …… [4] [Total: 17]

Question

This question is about metals. (a) Fig. 6.1 shows a blast furnace used to extract iron from its ore. waste gases air air slag A Fig. 6.1 (i) Coke and iron ore are added at the top of the blast furnace. Name one other substance that is added at the top of the blast furnace. . …… [1] (ii) Name the substance that leaves the blast furnace at A. . …… [1] (iii) Slag is produced from an impurity in iron ore. Name the impurity in iron ore that is converted into slag. . …… [1] (iv) Name two substances that react together to produce the high temperature in the blast furnace. …… and . …… [1] (v) Name two waste gases that leave the blast furnace. 1 . …… 2 . …… [2] (b) Zinc is produced from zinc oxide in a furnace. The zinc is produced as a gas. It then forms molten zinc. (i) Suggest why the zinc produced inside the furnace is a gas. . …… [1] (ii) State the name of the physical change that occurs when gaseous zinc is converted into molten zinc. . …… [1] (c) Zinc is used to coat iron to prevent rusting. (i) Name the process used to coat iron with zinc as a method of rust prevention. . …… [1] (ii) When the zinc coating is scratched, the iron underneath does not rust. Explain why the iron underneath the zinc does not rust. . …… . …… [2] (d) Zinc oxide neutralises both acids and bases. (i) State the general name given to oxides that neutralise both acids and bases. . …… [1] (ii) When zinc oxide neutralises aqueous sodium hydroxide, sodium zincate is formed. The formula of the zincate ion is ZnO22–. Deduce the formula of sodium zincate. . …… [1] (iii) Name the zinc compound that forms when zinc oxide neutralises dilute sulfuric acid. . …… [1] [Total: 14]

Question

Many organic compounds contain carbon and hydrogen only. (a) (i) Organic compound A has the following composition by mass. C, 82.76%; H, 17.24% Calculate the empirical formula of compound A. empirical formula = …… [3] (ii) Compound B has the empirical formula CH2 and a relative molecular mass of 70. Determine the molecular formula of compound B. molecular formula = …… [1] (b) Fig. 7.1 shows a section of polymer Q. CH3 CH3 CH3 CH3 C C C C H H H H Fig. 7.1 ● Draw the displayed formula of the monomer that forms polymer Q. ● Name the monomer used to form polymer Q. . …… [3] (c) Propene, C3H6, can be produced by heating C11H24. The products of the reaction are propene, hydrogen and one other product in a 1 : 1 : 1 mole ratio. Complete the symbol equation for this reaction. C11H24 → C3H6 + H2 + …… [1] (d) Carboxylic acids and esters contain carbon, hydrogen and oxygen only. An ester X and a carboxylic acid Y both contain 3 carbon atoms. X and Y have the same molecular formula. (i) State the name given to compounds with the same molecular formula but different structural formulae. . …… [1] (ii) Esters are made by the reaction between carboxylic acids and alcohols. Ester X is methyl ethanoate. Name the carboxylic acid and the alcohol used to make methyl ethanoate. carboxylic acid …… alcohol …… [2] (iii) Draw the displayed formula of carboxylic acid Y. Name the carboxylic acid. name . …… [2] [Total: 13] The Periodic Table of Elements Group I II III IV V VI VII VIII 1 2 H He hydrogen helium Key 1 4 3 4 atomic number 5 6 7 8 9 10 Li Be atomic symbol B C N O F Ne lithium beryllium name boron carbon nitrogen oxygen fluorine neon 7 9 relative atomic mass 11 12 14 16 19 20 11 12 13 14 15 16 17 18 Na Mg Al Si P S Cl Ar sodium magnesium aluminium silicon phosphorus sulfur chlorine argon 23 24 27 28 31 32 35.5 40 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton 39 40 45 48 51 52 55 56 59 59 64 65 70 73 75 79 80 84 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon 16 85 88 89 91 93 96 – 101 103 106 108 112 115 119 122 128 127 131 55 56 57–71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 lanthanoids Cs Ba Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn caesium barium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury thallium lead bismuth polonium astatine radon 133 137 178 181 184 186 190 192 195 197 201 204 207 209 – – – 87 88 89–103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 actinoids Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og francium radium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicium nihonium flerovium moscovium livermorium tennessine oganesson – – – – – – – – – – – – – – – – – 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 lanthanoids La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu lanthanum cerium praseodymium neodymium promethium samarium europium gadolinium terbium dysprosium holmium erbium thulium ytterbium lutetium 139 140 141 144 – 150 152 157 159 163 165 167 169 173 175 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 actinoids Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr actinium thorium protactinium uranium neptunium plutonium americium curium berkelium californium einsteinium fermium mendelevium nobelium lawrencium – 232 231 238 – – – – – – – – – – – The volume of one mole of any gas is 24 dm3 at room temperature and pressure (r.t.p.).