Chemistry 0620/42 May/June 2024: question paper and mark scheme

Question

A list of gases is shown. ammonia helium hydrogen carbon dioxide carbon monoxide chlorine methane nitrogen dioxide propene sulfur dioxide Answer the following questions about these gases. Each gas may be used once, more than once or not at all. (a) State one gas which: (i) is the main constituent of natural gas …… [1] (ii) is responsible for both photochemical smog and acid rain …… [1] (iii) is unsaturated …… [1] (iv) has monatomic particles …… [1] (v) reduces iron(III) oxide in a blast furnace. …… [1] (b) Nitrogen dioxide, NO2, and carbon monoxide are removed from a car exhaust by a catalytic converter. Write the symbol equation for this reaction. …… [2] [Total: 7]

Question

A list of five metals is shown. copper iron magnesium potassium silver (a) All metals form positive ions. (i) Describe how atoms form positive ions. …… [1] (ii) State which of the five metals in the list has the greatest tendency to form positive ions. …… [1] (iii) Suggest one of the five metals in the list which is not likely to show catalytic properties. …… [1] (iv) State which of the five metals in the list is a major component of stainless steel. …… [1] (b) A student adds a sample of a metal to an aqueous metal salt in a beaker to see if a displacement reaction takes place. Complete Table 2.1 to show the colour of the solution in the beaker at the start and at the end of the experiment. Table 2.1 metal aqueous solution colour at the start colour at the end magnesium iron(II) sulfate green silver copper(II) sulfate [3] (c) Most Group II metals form a gas when placed into cold water. An alkaline solution is also formed. (i) Name the gas formed when strontium is added to cold water. …… [1] (ii) Name the alkaline solution formed when strontium is added to cold water. …… [1] (iii) One Group II metal reacts very slowly when placed in cold water. When heated, the metal reacts with steam to form a white solid. Identify this metal and name the white solid formed. metal …… white solid …… [2] (d) Under certain conditions, iron will react with steam to form an oxide of iron with the formula Fe3O4. Fe3O4 reacts with dilute hydrochloric acid to form a mixture of iron(II) and iron(III) salts and water. Deduce the symbol equation for the reaction between Fe3O4 and dilute hydrochloric acid. …… [3] [Total: 14]

Question

The symbol equation for the industrial production of ammonia is shown. N2(g) + 3H2(g) 2NH3(g) ∆H = –90 kJ / mol (a) Name this industrial process. …… [1] (b) State the meaning of ∆H. …… [1] (c) State the typical conditions and name the catalyst used in the industrial production of ammonia. temperature and units …… pressure and units …… catalyst used …… [3] (d) State two methods of increasing the rate of this reaction. 1 …… 2 …… [2] (e) The symbol equation for the reaction can be represented as shown in Fig. 3.1. H H H N H H N H N N + H H + H = –90 kJ / mol H H H H Fig. 3.1 Table 3.1 shows some bond energies. Table 3.1 bond N≡N H–H bond energy in kJ / mol 945 435 Use the bond energies in Table 3.1 and ∆H to calculate the bond energy of an N–H bond, in kJ / mol. Use the following steps. ● Calculate the energy needed to break bonds in the reactants. …… kJ ● Calculate the energy released when bonds form in the products. …… kJ ● Calculate the energy of an N–H bond. …… kJ / mol (f) An incomplete symbol equation for the preparation of ammonia in the laboratory is shown. CaO + 2NH4Cl → CaCl 2 + …… + 2NH3 (i) Complete the symbol equation. [1] (ii) Name NH4Cl. …… [1] (iii) Calculate the volume of ammonia, NH3, measured at room temperature and pressure, which forms when 1.12 g of CaO is heated with excess NH4Cl. [Mr: CaO, 56] …… cm3 [3] [Total: 15]

Question

A carboxylic acid reacts with an alcohol to produce an ester and water. Under certain conditions, this reaction can be reversed so an ester reacts with water to produce a carboxylic acid X and an alcohol Y. The reaction reaches an equilibrium. CH3CH2COOCH3 + H2O X + Y The forward reaction is endothermic. (a) Deduce the empirical formula of the ester. …… [1] (b) Name the ester. …… [1] (c) Name carboxylic acid X and draw its displayed formula. name …… displayed formula [2] (d) Name alcohol Y and give its structural formula. name …… structural formula …… [2] (e) Complete Table 4.1 to show the effect, if any, for each change of condition. Table 4.1 effect on the concentration of change of condition carboxylic acid X at equilibrium temperature is decreased concentration of CH3CH2COOCH3 is decreased more alcohol Y is added a catalyst is added [4] (f) At the beginning of the reaction between the ester and water, no carboxylic acid is present in the reaction mixture. (i) Suggest how the pH of the reaction mixture changes from the start of the reaction until equilibrium is reached. Assume alcohols and esters are neutral. pH at start of reaction …… pH at equilibrium …… [2] (ii) Identify the ion that causes the change in pH. …… [1] (iii) Name an indicator which can be used to follow the change in pH. …… [1] [Total: 14]

Question

Sulfur is a Group VI element. (a) A sample of sulfur contains two isotopes, 32S and 34S. (i) Complete Table 5.1 to show the number of protons and neutrons in one atom of each isotope of sulfur. Table 5.1 32 S 34 S protons neutrons [2] (ii) State why these isotopes have identical chemical properties. …… [1] (iii) State the mass of 6.02 × 1023 atoms of 34S. Include units in your answer. …… [1] (iv) State the name of the amount of substance which contains 6.02 × 1023 atoms. …… [1] (v) Table 5.2 shows the relative abundance of these isotopes of sulfur in the sample. Table 5.2 atom 32 S 34 S relative abundance 95% 5% Calculate the relative atomic mass of sulfur in this sample to one decimal place. relative atomic mass = …… [2] (b) Sulfur reacts with magnesium to form magnesium sulfide, MgS, an ionic compound. (i) Complete the dot-and-cross diagram in Fig. 5.1 of the ions in magnesium sulfide. Give the charges on the ions. Mg S Fig. 5.1 [3] (ii) State why MgS has a high melting point. …… [1] (iii) State why molten MgS conducts electricity. …… [1] (c) An acid containing sulfur reacts with sodium hydroxide, NaOH, to form a salt and water. The salt has the formula Na2SO3. (i) Deduce the formula of this acid. …… [1] (ii) Deduce the formula of the anion in Na2SO3. …… [1] (d) Na2SO3 is oxidised by acidified aqueous potassium manganate(VII). (i) State what VII refers to in the name potassium manganate(VII). …… [1] (ii) State the colour change when this reaction happens. from …… to …… [2] . [Total: 17]

Question

Glucose is involved in two processes. (a) Glucose, C6H12O6, is made in plants from carbon dioxide and water. (i) Name this process. …… [1] (ii) Write the symbol equation for this process. …… [1] (iii) State two essential conditions needed for this process to happen. 1 …… 2 …… [2] (b) Glucose is converted to ethanol. (i) Name this process. …… [1] (ii) Name the other product formed when glucose is converted to ethanol. …… [1] (c) Ethanol is made by reacting ethene with steam in an industrial process. (i) State the conditions and type of catalyst used in this industrial production of ethanol. temperature and units …… pressure and units …… type of catalyst used …… [3] (ii) Explain why this reaction is an addition reaction. …… [1] (iii) Complete the dot-and-cross diagram in Fig. 6.1 of a molecule of ethanol. H H H C C O H H H Fig. 6.1 [3] [Total: 13] The Periodic Table of Elements Group I II III IV V VI VII VIII 1 2 H He hydrogen helium 1 4 Key 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.).