Chemistry 0620/42 February/March 2023: question paper and mark scheme

Question

This question is about gases found in clean, dry air and gases found in polluted air. (a) Name one gas found in clean, dry air which contributes to global warming. . …… [1] (b) State the percentage of nitrogen in clean, dry air. . …… [1] (c) Name the substance used to remove sulfur dioxide in flue gas desulfurisation. . …… [1] (d) Nitrogen dioxide, NO2, is formed in car engines. Name the equipment in a car exhaust used to remove the NO2 formed in car engines. . …… [1] (e) All gases diffuse. (i) Choose from the list of formulae the gas which diffuses most quickly. Draw a circle around your answer. CO CO2 CH4 NO2 SO2 [1] (ii) Explain your answer to (i). . …… [1] (f) State one adverse effect of carbon monoxide on human health. . …… [1] (g) Carbon dioxide, CO2, is a reactant in photosynthesis. Name the two products of photosynthesis. (h) Complete the dot-and-cross diagram in Fig. 1.1 for a molecule of CO2. Show outer shell electrons only. O C O Fig. 1.1 [2] [Total: 11]

Question

Lithium, sodium and potassium are Group I elements. (a) Name the type of bonding in these elements. . …… [1] (b) Sodium reacts with cold water to form hydrogen gas and a solution of a strong alkali. (i) State the test for hydrogen gas. test . …… positive result . …… [1] (ii) Suggest the pH of a solution of a strong alkali. pH = …… [1] (iii) Name a substance which can be used to confirm the pH of a solution of a strong alkali. . …… [1] (iv) Write the symbol equation for the reaction between sodium and cold water. Include state symbols. . …… [3] (c) Lithium has two naturally occurring types of atoms, 6Li and 7Li. (i) State the name given to atoms of the same element with different nucleon numbers. . …… [1] (ii) Complete Table 2.1 to show the number of protons, neutrons and electrons in the atom and ion of lithium shown. Table 2.1 6 Li 7 Li+ protons neutrons electrons [3] (iii) Table 2.2 shows the relative abundance of the two naturally occurring atoms of lithium. Table 2.2 atom 6 Li 7 Li relative abundance 10% 90% Calculate the relative atomic mass of lithium to one decimal place. relative atomic mass = …… [2] (d) Potassium oxide, K2O, is an ionic compound. Complete Fig. 2.1 to show the electronic configurations of the ions in potassium oxide. Show the charges on the ions. K O K Fig. 2.1 [3] [Total: 16]

Question

The Haber process is used to manufacture ammonia. (a) State the main source of each gas used in the Haber process. nitrogen . …… hydrogen . …… [2] (b) The equation for the Haber process is shown. N2(g) + 3H2(g) 2NH3(g) ∆H = –92 kJ / mol The reaction is reversible. The forward reaction is exothermic. (i) State what is meant by the symbol ∆H. . …… [1] (ii) ∆H for the forward reaction is –92 kJ / mol. State why this value shows that the forward reaction is exothermic. . …… [1] (iii) State the typical conditions and name the catalyst used in the Haber process. temperature …… °C pressure . …… kPa catalyst …… [3] (iv) Complete Table 3.1 to show the effect, if any, when the typical conditions in the Haber process are changed. Use only the words increases, decreases or no change. Table 3.1 change to effect on the rate of effect on the concentration typical conditions the forward reaction of NH3(g) at equilibrium temperature increases increases pressure decreases no catalyst decreases [4] (v) Explain in terms of collision theory why increasing the temperature increases the rate of the reaction. . …… . …… . …… . …… . …… [3] (c) Ammonia reacts with an acid to form ammonium sulfate, (NH4)2SO4. (i) State the formula of the acid used. . …… [1] (ii) State one use of ammonium sulfate. . …… [1] (iii) Calculate the percentage composition by mass of nitrogen in (NH4)2SO4. percentage of nitrogen = …… % [2] [Total: 18]

Question

Copper is element 29 in the Periodic Table. (a) Brass contains copper. (i) Name the other metal in brass. . …… [1] (ii) State the term given to a mixture of a metal with another element. . …… [1] (b) Copper can be stretched into wires. Copper wires conduct electricity. (i) Name the property of metals which means that they can be stretched into wires. . …… [1] (ii) Name the particles responsible for the conduction of electricity in solid copper. . …… [1] (c) Copper is a transition element. Some physical and chemical properties of transition elements are shown. physical properties: ● high density ● high strength chemical properties: ● form coloured compounds ● have ions with variable oxidation numbers (i) State one other physical property of transition elements. . …… [1] (ii) State one other chemical property of transition elements. . …… [1] (d) Hydrated copper(II) sulfate is a coloured compound. It exists as hydrated crystals which contain water molecules. (i) State the term given to water molecules present in hydrated crystals. . …… [1] (ii) State the colour of hydrated copper(II) sulfate crystals. . …… [1] (iii) Write the formula of hydrated copper(II) sulfate. . …… [2] (e) Copper(II) oxide is formed when copper(II) nitrate, Cu(NO3)2, is heated. 2Cu(NO3)2(s) → 2CuO(s) + 4NO2(g) + O2(g) (i) State the class of oxide to which copper(II) oxide belongs. . …… [1] (ii) State the meaning of the Roman numeral (II) in the name copper(II) oxide. . …… [1] (iii) 0.0200 moles of Cu(NO3)2 is heated. Calculate the mass of 0.0200 moles of Cu(NO3)2. mass = …… g [2] (iv) Calculate the total volume of gas, in dm3 at r.t.p., produced when 0.0200 moles of Cu(NO3)2 is heated. volume = …… dm3 [2] (v) Powdered aluminium reduces copper(II) oxide. Write the symbol equation for this reaction. . …… [2] [Total: 18]

Question

Propane, propene, propan-1-ol and propanoic acid are members of different homologous series. Molecules of these substances contain three carbon atoms. (a) Explain why members of a homologous series have similar chemical properties. . …… [1] (b) Name the homologous series to which propanoic acid belongs. . …… [1] (c) State the general formula of the homologous series to which propanoic acid belongs. . …… [1] (d) Propan-1-ol has an unbranched isomer. ● Name this isomer. . …… ● Draw the displayed formula of this isomer. [2] (e) Propane and propene can be manufactured by heating decane, C10H22, in the presence of a catalyst. One other product is formed. (i) Complete the equation for this reaction. C10H22 → …… + …… + …… [2] (ii) Name this manufacturing process. . …… [1] (f) Propene forms a polymer named poly(propene). (i) Draw the displayed formula of a section of poly(propene) showing three repeat units. [2] (ii) State the type of polymerisation that occurs when propene forms poly(propene). . …… [1] (g) Propanoic acid reacts with aqueous sodium carbonate to form a salt. (i) Suggest the name of the salt formed. . …… [1] (ii) Suggest the formula of the anion in this salt. . …… [1] (h) Propanoic acid forms an ester when it reacts with ethanol in the presence of a catalyst. (i) Suggest a suitable catalyst. . …… [1] (ii) Name the ester formed. . …… [1] (iii) Draw the displayed formula of this ester. [2] [Total: 17] 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.).