Chemistry 0620/41 October/November 2021: question paper and mark scheme

Question

Some elements are shown in the order they appear in the reactivity series. The most reactive element is at the top. sodium calcium magnesium aluminium zinc iron hydrogen copper (a) Answer the questions using the list of elements. Each element may be used once, more than once or not at all. Identify: (i) a non-metal . …… [1] (ii) a metal which is stored under oil . …… [1] (iii) the main component of steel . …… [1] (iv) a metal with three electrons in the outer shell of its atoms . …… [1] (v) a metal found in brass . …… [1] (vi) a metal that forms chlorides of the type XCl 2 and XCl 3. . …… [1] (b) Name the main ores of: (i) zinc …… [1] (ii) aluminium. …… [1] (c) In an experiment, a sample of aluminium appeared less reactive than expected. Explain why. . …… . …… [1] (d) Name two metals from the list which are extracted by reduction of their ores using carbon. 1 . …… 2 . …… [2] (e) When zinc granules are added to aqueous copper(II) sulfate, a reaction occurs. During the reaction, a red-pink solid is formed and the solution becomes colourless. (i) Name the red-pink solid. . …… [1] (ii) Name the colourless solution. . …… [1] (iii) Explain, in terms of particles, why the rate of this reaction increases when the temperature is increased. . …… . …… . …… . …… . …… . …… [3] (iv) Suggest two other ways of increasing the rate of this reaction. 1 . …… 2 . …… [2] [Total: 18]

Question

This question is about copper and its compounds. (a) Copper has two different naturally occurring atoms, 63Cu and 65Cu. (i) State the term used for atoms of the same element with different nucleon numbers. . …… [1] (ii) The atomic number of copper is 29. Complete the table to show the number of protons, neutrons and electrons in the particles of copper shown. 63 Cu 65 Cu2+ protons neutrons electrons [3] (iii) Relative atomic mass is the average mass of naturally occurring atoms of an element. The percentage of the naturally occurring atoms in a sample of copper is shown. 63 Cu 65 Cu 70% 30% Deduce the relative atomic mass of copper in this sample. Give your answer to one decimal place. relative atomic mass = …… [2] (b) Anhydrous copper(II) sulfate is used to test for the presence of water. When this test is positive, hydrated copper(II) sulfate is formed. (i) State the colour change seen during this test. from …… to …… [2] (ii) Complete the chemical equation to show the reaction that takes place. CuSO4 + …… CuSO4•5H2O[1] (iii) State how hydrated copper(II) sulfate can be turned back into anhydrous copper(II) sulfate. . …… [1] (iv) Describe a test for pure water. . …… . …… [2] (c) Aqueous copper(II) sulfate contains Cu2+(aq) ions. Describe what is seen when aqueous copper(II) sulfate is added to aqueous (i) sodium hydroxide, NaOH(aq). . …… [1] (ii) Write the ionic equation for the reaction between aqueous copper(II) sulfate and aqueous sodium hydroxide. Include state symbols. . …… [3] (d) When solid copper(II) nitrate is heated copper(II) oxide, nitrogen dioxide and oxygen are formed. 2Cu(NO3)2 → 2CuO + 4NO2 + O2 Calculate the volume of nitrogen dioxide formed at room temperature and pressure when 4.7 g of Cu(NO3)2 is heated. Use the following steps: ● calculate the mass of one mole of Cu(NO3)2 …… g ● calculate the number of moles of Cu(NO3)2 used …… moles ● determine the number of moles of nitrogen dioxide formed …… moles ● calculate the volume of nitrogen dioxide formed at room temperature and pressure. …… dm3 [4] (e) Write the chemical equation to show the action of heat on sodium nitrate, NaNO3. . …… [2] [Total: 22]

Question

This question is about electrolysis. Concentrated hydrochloric acid is electrolysed using the apparatus shown. wire + – carbon electrodes concentrated hydrochloric acid (a) Chloride ions are discharged at the anode. (i) Complete the ionic half-equation for this reaction. ……Cl –(aq) → ……(g) + ……e–[2] (ii) State whether oxidation or reduction takes place. Explain your answer. . …… . …… [1] (b) Describe what is seen at the cathode. . …… [1] (c) Write the ionic half-equation for the reaction at the cathode. . …… [2] (d) The pH of the electrolyte is measured throughout the experiment. (i) Suggest the pH of the electrolyte at the beginning of the experiment. . …… [1] (ii) State how the pH changes, if at all, during the experiment. Explain your answer. . …… . …… [2] (e) The electrolysis is repeated using molten lead(II) bromide. Describe what is seen at the: ● cathode . …… ● anode. . …… [2] (f) State two properties of graphite (carbon) which make it suitable for use as an electrode. 1 . …… 2 . …… [2] [Total: 13]

Question

Chalcopyrite, FeCuS2, is used in the manufacture of sulfuric acid in the Contact process. (a) In the first stage of the process, chalcopyrite reacts with oxygen in the air to produce sulfur dioxide, SO2, iron(III) oxide and copper(II) oxide. Complete the chemical equation for the reaction of FeCuS2 with oxygen. 4FeCuS2 + 13O2 → …… + …… + …… [2] (b) Sulfur dioxide is then converted to sulfur trioxide. 2SO2 + O2 2SO3 The reaction is exothermic. It is also an equilibrium. (i) State two features of an equilibrium. 1 . …… 2 . …… [2] (ii) State the temperature and pressure used in this reaction. Include units. ● temperature …… ● pressure . …… [2] (iii) Name the catalyst used. . …… [1] (iv) Explain why a catalyst is used. . …… [1] (v) Describe and explain, in terms of equilibrium, what happens when the temperature is increased. . …… . …… [2] (c) Concentrated sulfuric acid is a dehydrating agent. When glucose is dehydrated, carbon and one other product are formed. Complete the equation to show the dehydration of glucose, C6H12O6. C6H12O6 → ……C + …… [2] [Total: 12]

Question

Alkenes and carboxylic acids are both families of similar compounds with similar chemical properties. Alkenes and carboxylic acids have different reactions. (a) State the term used for a ‘family’ of similar compounds. . …… [1] (b) State the general formula of alkenes. . …… [1] (c) The structure of but-2-ene is shown. H H H H C C C C H H H H (i) But-2-ene reacts with aqueous bromine in an addition reaction. Describe the colour change seen when but-2-ene is added to aqueous bromine. from …… to …… [1] (ii) State what is meant by the term addition reaction. . …… [1] (iii) Write the chemical equation for the reaction between but-2-ene and bromine. . …… [2] (iv) But-2-ene forms a polymer. Suggest the name of the polymer formed from but-2-ene. . …… [1] (v) Name and draw a structural isomer of but-2-ene. Show all of the atoms and all of the bonds. name . …… structure [2] (d) Butanoic acid, CH3CH2CH2COOH, is a carboxylic acid. (i) Deduce the empirical formula of butanoic acid. . …… [1] (ii) Complete the chemical equation for the reaction of butanoic acid and sodium carbonate, Na2CO3. 2CH3CH2CH2COOH + Na2CO3 → …… + …… + …… [2] (iii) Butanoic acid reacts with methanol to form an organic compound and water. ● Name the organic compound formed. . …… [1] ● Draw the structure of the organic compound formed. Show all of the atoms and all of the bonds. [2] [Total: 15] 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 12 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.).