Chemistry 0620/43 October/November 2023: question paper and mark scheme

Question

A list of substances is shown. barium nitrate carbon monoxide hydrated cobalt(II) chloride copper(II) oxide anhydrous copper(II) sulfate ethane potassium iodide propene sodium bromide sulfur dioxide zinc oxide Answer the following questions using only the substances from the list. Each substance may be used once, more than once or not at all. Give the name of the substance that: (a) gives a lilac colour in a flame test . …… [1] (b) forms a cream precipitate when its aqueous solution reacts with acidified aqueous silver nitrate . …… [1] (c) is an acidic oxide . …… [1] (d) is an unsaturated hydrocarbon . …… [1] (e) is a product of incomplete combustion of fossil fuels . …… [1] (f) is used to test for the presence of water. . …… [1] [Total: 6]

Question

Table 2.1 gives information about particles A, B, C, D, E and F. Table 2.1 number of number of number of particle electrons neutrons protons A 5 6 5 B 10 11 10 C 10 14 13 D 18 17 16 E 18 17 17 F 15 16 15 (a) Give the letters of all the particles which are: (i) atoms . …… [1] (ii) ions with a charge of 2– . …… [1] (iii) cations. . …… [1] (b) State the atomic number of A. . …… [1] (c) Determine the number of nucleons in D. . …… [1] (d) State the electronic configuration of D. . …… [1] (e) State the group number of F. . …… [1] (f) State the period number of B. . …… [1] [Total: 8]

Question

This question is about nitrogen and some of its compounds. (a) Nitrogen is converted into ammonia, NH3, in the Haber process. (i) Nitrogen is obtained from air. State the percentage of nitrogen in clean, dry air. . …… [1] (ii) State the source of hydrogen for the Haber process. . …… [1] (iii) Complete the dot-and-cross diagram in Fig. 3.1 for a molecule of ammonia. Show the outer shell electrons only. H H N H Fig. 3.1 [2] (iv) Write a chemical equation for the reaction occurring in the Haber process and give the typical reaction conditions. Include units where appropriate. chemical equation . …… reaction conditions: temperature …… pressure . …… catalyst …… [5] (b) Ammonia is converted into nitric acid. The first stage of this conversion uses a catalyst and occurs at a temperature of 900 °C and a pressure of 5 atmospheres. 4NH3(g) + 5O2(g) 4NO(g) + 6H2O(g) The forward reaction is exothermic. (i) Suggest which of the following elements is most likely to be used as a catalyst. Draw a circle around your answer. calcium lead platinum sodium sulfur[1] (ii) State the oxidation number of nitrogen in: NH3 …… NO …… [2] (iii) Use your answer to (ii) to explain whether the nitrogen in ammonia undergoes oxidation or reduction. . …… . …… [1] (iv) Complete Table 3.1 using the words increases, decreases or no change. Table 3.1 effect on the equilibrium effect on the rate of yield of NO(g) the forward reaction decreasing the pressure decreasing the temperature decreases removing the catalyst decreases [4] (v) Decreasing the temperature causes the rate of the forward reaction to decrease. Explain, using collision theory, why the rate of the reaction is slower at the decreased temperature. . …… . …… . …… . …… [3] (c) In the second stage, nitric acid is produced. Balance the symbol equation for this reaction. ……NO + ……O2 + ……H2O → ……HNO3[1] [Total: 21]

Question

This question is about sulfuric acid and salts that are made from sulfuric acid. (a) Zinc reacts with dilute sulfuric acid. Aqueous zinc sulfate is one of the products. Powdered zinc is added to dilute sulfuric acid. The mixture is stirred. More zinc is added, with stirring, until the zinc is in excess. Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g) The mixture is then filtered. (i) Name the limiting reactant. . …… [1] (ii) State two observations that indicate the zinc is in excess. 1 . …… 2 . …… [2] (iii) Name the filtrate. . …… [1] (iv) Name two compounds which both react with dilute sulfuric acid to produce aqueous zinc sulfate. 1 . …… 2 . …… [2] (b) Zinc sulfate crystals are produced by heating aqueous zinc sulfate until a saturated solution is formed. When the saturated solution cools down, crystals of zinc sulfate start to form. (i) State what is meant by the term saturated solution. . …… . …… [2] (ii) Explain why crystals form when the saturated solution cools down. . …… [1] (c) Nickel(II) sulfate crystals contain water of crystallisation. When nickel(II) sulfate crystals, NiSO4•xH2O, are heated, they give off water. NiSO4•xH2O(s) → NiSO4(s) + xH2O(g) A student carries out an experiment to determine the value of x in NiSO4•xH2O. step 1 Nickel(II) sulfate crystals are weighed. step 2 Nickel(II) sulfate crystals are heated. step 3 The remaining solid is allowed to cool and is then weighed. step 4 The remaining solid is heated again, allowed to cool and is then weighed. step 5 Step 4 is repeated until there is no change in mass. (i) State the term used to describe crystals that contain water of crystallisation. . …… [1] (ii) State why step 4 is repeated until there is no change in mass. . …… [1] (iii) In an experiment, 0.454 g of nickel(II) sulfate crystals, NiSO4•xH2O, is used. The mass of anhydrous nickel(II) sulfate, NiSO4, remaining is 0.310 g. [Mr: NiSO4, 155; H2O, 18] Determine the value of x in NiSO4•xH2O. Use the following steps. ● Calculate the number of moles of NiSO4 remaining. moles of NiSO4 = …… ● Calculate the mass of H2O given off. mass of H2O = …… g ● Calculate the number of moles of H2O given off. moles of H2O = …… ● Calculate the value of x. x = …… [4] [Total: 15]

Question

This question is about iron. (a) (i) Describe the bonding in a metallic element such as iron. You may include a labelled diagram as part of your answer. . …… . …… . …… [3] (ii) Explain why iron conducts electricity when it is solid. . …… [1] (b) Iron is extracted from hematite in the blast furnace as shown in Fig. 5.1. waste gases coke, hematite, limestone air air slag molten iron Fig. 5.1 (i) Give two reasons why coke is added to the blast furnace. 1 . …… 2 . …… [2] (ii) Explain how limestone removes the impurities in the hematite. . …… . …… . …… [2] (iii) Hematite contains iron(III) oxide. Write a symbol equation for the conversion of iron(III) oxide to iron in the blast furnace. . …… [2] (iv) Suggest why the iron produced in the blast furnace is molten. . …… [1] (c) Most iron is converted into steel. Steel is an alloy. Steel is more useful than pure iron because it is harder and stronger. Explain why the structure of alloys causes them to be harder and stronger than pure metals. You may include a diagram as part of your answer. . …… . …… [2] (d) Iron forms rust. Rusting is prevented by coating iron with zinc. (i) Name the substances that react with iron to form rust. . …… [1] (ii) Name the process in which zinc is used to coat iron to prevent rusting. . …… [1] (iii) Explain how the coating of zinc prevents rusting if the zinc is not scratched. . …… [1] (iv) When zinc is scratched the iron becomes exposed. Explain how the zinc continues to prevent rusting. . …… . …… . …… [2] [Total: 18]

Question

(a) Esters are members of a homologous series of organic compounds. Give two characteristics that are the same for all members of a homologous series. 1 . …… 2 . …… [2] (b) Ester X has the structure shown in Fig. 6.1. H H O H C C C H H H H O C C H H H Fig. 6.1 Name ester X. . …… [1] (c) (i) Ester Y has the structural formula HCOOCH2CH2CH3. Name the alcohol and the carboxylic acid used to make ester Y. alcohol …… carboxylic acid …… [2] (ii) State the molecular formula of ester Y. . …… [1] (d) Ester Z has the molecular formula C4H8O2. State the empirical formula of ester Z. . …… [1] (e) Polymers containing ester linkages are known as polyesters. Polyamides are another type of polymer. Nylon is a polyamide. The structure of nylon is shown in Fig. 6.2. O O C C N N H H Fig. 6.2 (i) State the term used to describe the type of polymerisation used to produce polyesters and polyamides. . …… [1] (ii) Complete Fig. 6.3 to show the structures of the monomers used to produce nylon. Show all of the atoms and all of the bonds. Fig. 6.3 [2] (f) Naturally occurring polyamides are found in food. (i) State the name given to naturally occurring polyamides. . …… [1] (ii) Name the type of monomer which forms naturally occurring polyamides. . …… [1] [Total: 12] 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.).