Chemistry 0620/43 May/June 2022: question paper and mark scheme

Question

A list of substances is shown. aluminium oxide carbon dioxide carbon monoxide chlorine copper glucose iron(III) oxide limestone nitrogen oxygen Answer the questions using the substances in the list. Each substance may be used once, more than once or not at all. State which substance is: (a) a product of respiration . …… [1] (b) the main constituent of hematite . …… [1] (c) an element which has a sulfate that is used to test for water . …… [1] (d) a colourless toxic gas . …… [1] (e) a reactant in fermentation . …… [1] (f) a reducing agent in the extraction of iron . …… [1] (g) a conductor of electricity when solid . …… [1] (h) a gas that is approximately 21% of clean, dry air. . …… [1] [Total: 8]

Question

(a) 16S and 16S are isotopes of sulfur. 32 33 Use your knowledge of protons, neutrons and electrons to answer the following questions. (i) Describe how these isotopes of sulfur are the same and how they are different. same . …… . …… different . …… . …… [3] (ii) Explain why each of these isotopes have an overall charge of zero. . …… . …… [1] (iii) Explain why both isotopes have the same chemical properties. . …… . …… [1] (b) Sulfide ions, S2–, have the electronic structure 2,8,8. (i) Explain why sulfide ions have a charge of 2–. . …… . …… [1] (ii) Give the formula of: ● an anion which has the same electronic structure as S2– . …… ● a cation which has the same electronic structure as S2–. . …… [2] [Total: 8]

Question

This question is about nitrogen and compounds of nitrogen. (a) Nitrogen molecules have the formula N2. Some properties of nitrogen are shown: ● melting point of –210 °C ● boiling point of –196 °C ● non-conductor of electricity when solid ● insoluble in water. (i) Name the type of bonding between the atoms in an N2 molecule. . …… [1] (ii) Explain, in terms of attractive forces between particles, why nitrogen has a low melting point. . …… . …… [1] (iii) Explain why nitrogen does not conduct electricity. . …… . …… [1] (b) Nitrogen reacts with hydrogen to form ammonia, NH3, in the Haber process. State the essential conditions in the Haber process. Write an equation for the chemical reaction. . …… . …… . …… . …… . …… [4] (c) Ammonia is made in the laboratory by heating ammonium chloride with calcium hydroxide. Balance the chemical equation for the reaction. ……NH4Cl + Ca(OH)2 → ……NH3 + CaCl 2 + ……H2O[1] (d) Hydrazine, N2H4, is another compound that contains nitrogen and hydrogen. Complete the dot-and-cross diagram to show the electron arrangement in a molecule of hydrazine. Show outer electrons only. H H N N H H [2] (e) Ammonia and hydrazine are weak bases. The chemical equation for the reaction between one molecule of ammonia and one molecule of water is shown. NH3 + H2O NH4+ + OH– (i) State the meaning of the term base. . …… [1] (ii) Write a chemical equation for the reaction between one molecule of hydrazine, N2H4, and one molecule of water. . …… [1] [Total: 12]

Question

Ethanol is made industrially by the reaction of ethene with steam. The reaction occurs at a temperature of 300 °C and a pressure of 60 atmospheres. C2H4(g) + H2O(g) C2H5OH(g) A catalyst is used in this reaction. The forward reaction is exothermic. (a) State what is meant by the term catalyst. . …… . …… [2] (b) Complete the table using only the words increases, decreases or no change. effect on the rate of effect on the equilibrium the forward reaction yield of C2H5OH(g) increasing the temperature decreasing the pressure [4] (c) Ethanol is a member of the alcohol homologous series. Members of the same homologous series have the same general formula. (i) State the general formula of alcohols. . …… [1] (ii) State two general characteristics, other than the same general formula, of all homologous series. 1 . …… 2 . …… [2] (iii) One alcohol containing three carbon atoms is propan-1-ol. Draw the structure of one other alcohol containing three carbon atoms. Show all of the atoms and all of the bonds. Name the alcohol you have drawn. name . …… [2] (d) When alcohols react with carboxylic acids, esters are produced. (i) The structure of ester X is shown. H H H O H C C C C H H H H H O C C H H H Name ester X. . …… [1] (ii) Give the name of the alcohol and the carboxylic acid that react together to produce ester X. alcohol …… carboxylic acid …… [2] (e) Ester Y has the following composition by mass: C, 58.82%; H, 9.80%; O, 31.37%. Calculate the empirical formula of ester Y. empirical formula = …… [3] (f) Ester Z has the empirical formula C3H6O and a relative molecular mass of 116. Calculate the molecular formula of ester Z. molecular formula = …… [1] [Total: 18]

Question

This question is about copper and its compounds. (a) Describe the bonding in a metallic element such as copper. You may include a diagram as part of your answer. . …… . …… . …… [3] (b) A metal spoon is electroplated with copper. State what is used as: the positive electrode (anode) …… the negative electrode (cathode) …… the electrolyte. …… [3] (c) The formula for crystals of hydrated copper(II) sulfate is CuSO4•5H2O. Hydrated copper(II) sulfate is made by reacting copper(II) oxide with dilute sulfuric acid. The overall equation is shown. CuO + H2SO4 + 4H2O → CuSO4•5H2O The crystals are made using the following steps: step 1 50.0 cm3 of 0.200 mol / dm3 dilute sulfuric acid is heated in a beaker. Powdered copper(II) oxide is added until the copper(II) oxide is in excess. Aqueous copper(II) sulfate is formed. step 2 The excess copper(II) oxide is separated from the aqueous copper(II) sulfate. step 3 The aqueous copper(II) sulfate is heated until a saturated solution is formed. step 4 The saturated solution is allowed to cool and crystallise. step 5 The crystals are removed and dried. Calculate the maximum mass of copper(II) sulfate crystals, CuSO4•5H2O, that can form using the following steps. ● Calculate the number of moles of H2SO4 in 50.0 cm3 of 0.200 mol / dm3 H2SO4. …… mol ● Deduce the number of moles of CuSO4•5H2O that can form. …… mol ● The Mr of CuSO4•5H2O is 250. Calculate the maximum mass of CuSO4•5H2O that can form. …… g [3] (d) State one observation that indicates the copper(II) oxide is in excess in step 1. . …… [1] (e) Step 1 is repeated without heating the dilute sulfuric acid. All other conditions are kept the same. The rate of reaction decreases. Give a reason why the rate of reaction decreases. Explain your answer in terms of particles. . …… . …… . …… . …… . …… [3] (f) Name a substance, other than copper(II) oxide, that can be added to dilute sulfuric acid to produce copper(II) sulfate in step 1. . …… [1] (g) Name the process used to separate excess copper(II) oxide from aqueous copper(II) sulfate in step 2. . …… [1] (h) Suggest what is meant by the term saturated solution in step 3. . …… . …… . …… [2] (i) The phrase ‘heating to dryness’ means heating until no more water is given off. Explain why aqueous copper(II) sulfate is not heated to dryness in step 3. . …… . …… [1] [Total: 18]

Question

The Periodic Table can be used to classify elements. (a) The Group I metals react with cold water. Transition elements do not react with cold water. (i) Describe two other differences in the chemical properties between Group I metals and transition elements. 1 . …… 2 . …… [2] (ii) Describe the observations when potassium is added to cold water. Write a balanced equation for the reaction. Include state symbols. observations …… . …… . …… . …… equation . …… [5] (b) Transition elements are stronger than Group I metals. Describe two other differences in the physical properties of Group I metals and transition elements. 1 . …… 2 . …… [2] (c) Some Group VII elements react with aqueous solutions containing halide ions. When aqueous bromine is added to aqueous potassium iodide a reaction occurs. The ionic half-equations for the reaction are shown. Br2(aq) + 2e– → 2Br –(aq) 2I–(aq) → I2(aq) + 2e– (i) Describe the colour change of the solution. original colour of potassium iodide solution . …… final colour of reaction mixture . …… [2] (ii) State the name of the general term given to the type of reaction in which electrons are transferred from one species to another. . …… [1] (iii) Identify the oxidising agent in this reaction. Give a reason for your answer. oxidising agent . …… reason . …… [2] (d) Use the key to complete the table to show the results of adding aqueous halogens to aqueous solutions of halides. One has been completed for you. halides KCl (aq) KBr(aq) KI(aq) Cl 2(aq) key ✓ = reaction ✗ = no reaction halogens Br2(aq) ✓ I2(aq) [2] [Total: 16] 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 89–103 104 105 106 107 108 109 110 111 112 114 116 actinoids Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Cn Fl Lv francium radium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicium flerovium livermorium – – – – – – – – – – – – – 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.).