Chemistry 0620/42 May/June 2023: question paper and mark scheme

Question

A list of oxides, A to H, is shown. A calcium oxide B aluminium oxide C silicon(IV) oxide D sulfur dioxide E carbon dioxide F iron(III) oxide G silver oxide H carbon monoxide Answer the following questions about the oxides, A to H. Each letter may be used once, more than once or not at all. State which of the oxides, A to H: (a) is responsible for acid rain (b) has a giant covalent structure (c) is a reducing agent in the blast furnace (d) is the main constituent of bauxite (e) is the main impurity in iron ore (f) can be reduced by heating with copper. [Total: 6]

Question

Fluorine, chlorine and bromine are in Group VII of the Periodic Table. (a) State the name given to Group VII elements. . …… [1] (b) Explain why Group VII elements have similar chemical properties. . …… [1] (c) Complete Table 2.1 to show the colour and state at r.t.p. of some Group VII elements. Table 2.1 element colour state at r.t.p. fluorine pale yellow chlorine bromine liquid [3] (d) Bromine has two naturally occurring isotopes, 79Br and 81Br. (i) State the term given to the numbers 79 and 81 in these isotopes of bromine. . …… [1] (ii) Complete Table 2.2 to show the number of protons, neutrons and electrons in the atom and ion of bromine shown. Table 2.2 79 Br 81 Br – protons neutrons electrons [3] (iii) Table 2.3 shows the relative abundances of the two naturally occurring isotopes of bromine. Table 2.3 isotope 79 Br 81 Br relative abundance 55% 45% Calculate the relative atomic mass of bromine to one decimal place. relative atomic mass = …… [2] (e) Chlorine displaces bromine from aqueous potassium bromide but does not displace fluorine from aqueous sodium fluoride. (i) Write the symbol equation for the reaction between chlorine and aqueous potassium bromide. . …… [2] (ii) State why chlorine does not displace fluorine from aqueous sodium fluoride. . …… [1] (f) Aqueous silver nitrate is a colourless solution containing Ag+(aq) ions. (i) Describe what is seen when aqueous silver nitrate is added to aqueous sodium chloride. . …… [1] (ii) Write the ionic equation for the reaction between aqueous silver nitrate and aqueous sodium chloride. Include state symbols. . …… [3] [Total: 18]

Question

Over 200 million tonnes of sulfuric acid are manufactured every year. (a) State the name of the process used to manufacture sulfuric acid. . …… [1] (b) Part of the manufacture of sulfuric acid involves converting sulfur dioxide to sulfur trioxide. (i) Describe two methods by which sulfur dioxide is obtained. 1 . …… 2 . …… [2] The conversion of sulfur dioxide to sulfur trioxide is a reversible reaction which can reach equilibrium. 2SO2(g) + O2(g) 2SO3(g) (ii) State two features of an equilibrium. 1 . …… 2 . …… [2] (iii) State the typical conditions and name the catalyst used in the conversion of sulfur dioxide to sulfur trioxide. temperature …… °C pressure . …… kPa catalyst …… [3] (iv) Complete Table 3.1 to show the effect, if any, when the following changes are applied to the conversion of sulfur dioxide to sulfur trioxide. 2SO2(g) + O2(g) 2SO3(g) The forward reaction is exothermic. Only use the words increases, decreases or no change. Table 3.1 effect on the rate of effect on the concentration change the forward reaction of SO3(g) at equilibrium temperature decreases decreases pressure increases no catalyst decreases [4] (v) Explain in terms of collision theory why reducing the temperature decreases the rate of the forward reaction. . …… . …… . …… . …… . …… [3] (c) Sulfuric acid contains SO42– ions. The oxidation number of O atoms in SO42– ions is –2. Determine the oxidation number of S atoms in SO42– ions. Show your working. oxidation number = …… [2] [Total: 17]

Question

Solid sodium hydroxide is a base which dissolves to form an aqueous solution, NaOH(aq). (a) State what is meant by the term base. . …… [1] (b) State the term given to a base which dissolves to form an aqueous solution. . …… [1] (c) State the colour of thymolphthalein in NaOH(aq). . …… [1] (d) Complete the word equation for the reaction of NaOH(aq) with ammonium chloride. sodium ammonium …… + → + …… + …… hydroxide chloride [3] (e) Some metal oxides react with NaOH(aq). (i) State the term given to metal oxides which react with bases such as NaOH(aq). . …… [1] (ii) Name a metal oxide which reacts with NaOH(aq). . …… [1] (f) Ethanoic acid, CH3COOH, is a weak acid. (i) Complete the dot-and-cross diagram in Fig. 4.1 of a molecule of ethanoic acid. H O H C C H O H Fig. 4.1 [3] (ii) Suggest the pH of dilute ethanoic acid. . …… [1] (iii) Complete the symbol equation to show the dissociation of ethanoic acid. CH3COOH …… [3] (iv) Write the ionic equation for the reaction when an acid neutralises a soluble base. . …… [1] (g) In a titration, 25.0 cm3 of 0.0800 mol / dm3 aqueous potassium hydroxide, KOH(aq), is neutralised by 20.0 cm3 of dilute sulfuric acid, H2SO4(aq). 2KOH(aq) + H2SO4(aq) → K2SO4(aq) + 2H2O(l) Calculate the concentration of H2SO4, in g / dm3 using the following steps. ● Calculate the number of moles of KOH used. …… mol ● Determine the number of moles of H2SO4 which react with the KOH. …… mol ● Calculate the concentration of H2SO4 in mol / dm3. …… mol / dm3 ● Calculate the concentration of H2SO4 in g / dm3. …… g / dm3 [5] [Total: 21]

Question

Propane and propene both react with chlorine. (a) When a molecule of propane, C3H8, reacts with chlorine in the presence of ultraviolet light, one atom of hydrogen is replaced by one atom of chlorine. (i) State the term given to reactions in which one atom in an alkane is replaced by another atom. . …… [1] (ii) State the purpose of ultraviolet light in this reaction. . …… [1] (iii) State the term given to any reaction which requires ultraviolet light. . …… [1] (iv) Write the symbol equation for the reaction between propane and chlorine. . …… [2] (b) A molecule of propene, C3H6, is unsaturated and will react with chlorine at room temperature. (i) State why propene is an unsaturated molecule. . …… [1] (ii) Give the structural formula of the product of this reaction. . …… [1] (c) Propene undergoes addition reactions with steam. There are two possible products, A and B. Draw the displayed formula and name each product. displayed formula of product A name of product A …… displayed formula of product B name of product B …… [4] [Total: 11]

Question

Carboxylic acids can be converted to esters. (a) Name the ester formed when butanoic acid, CH3CH2CH2COOH, reacts with ethanol, CH3CH2OH. . …… [1] (b) Identify the other product formed in this reaction. . …… [1] (c) Deduce the empirical formula of the ester formed. . …… [1] (d) PET is a polyester. Part of the structure of PET is shown in Fig. 6.1. O O O O C C O O C C O O Fig. 6.1 (i) Circle one repeat unit of this polymer. [1] (ii) Draw the structures of the monomers which make up PET. Draw the functional groups using displayed formulae. [2] (iii) State the type of polymerisation used in making PET. . …… [1] [Total: 7] 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 89–103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 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.).