Chemistry 0620/32 February/March 2022: question paper and mark scheme

Question

(a) The electronic structures of five atoms, A, B, C, D and E, are shown. A B C D E Answer the following questions about these electronic structures. Each electronic structure may be used once, more than once or not at all. State which electronic structure, A, B, C, D or E, represents: (i) an atom in Group V of the Periodic Table . …… [1] (ii) an atom which contains only two shells of electrons . …… [1] (iii) an atom that forms a stable ion with a charge of 2– . …… [1] (iv) an atom of an element that exists as a monoatomic gas . …… [1] (v) an atom of the metal that is extracted from bauxite. . …… [1] (b) Complete the table to show the number of electrons, neutrons and protons in the uranium atom and rubidium ion shown. number of electrons number of neutrons number of protons 92U 235 92 37Rb 87 + 50 [3] [Total: 8]

Question

(a) Biogas is a mixture of gases produced when agricultural waste is broken down in the absence of oxygen. The table compares the percentage by mass of the gases present in two samples of biogas, X and Y. biogas X biogas Y gas / % by mass / % by mass carbon dioxide 26 32 hydrogen 1 1 hydrogen sulfide 0.5 0.5 methane 67 56 nitrogen 4 9.5 oxygen 0.5 0.5 other gases 0.5 Answer these questions using only the information in the table. (i) Deduce the percentage by mass of the other gases in biogas X. . …… [1] (ii) Describe two major differences in the compositions of biogas X and biogas Y. 1 . …… 2 . …… [2] (b) Complete the diagram to show the electronic structure in a methane molecule. Show only the outer shell electrons. [1] (c) Hydrogen sulfide burns in air to produce sulfur dioxide and water. (i) Complete the chemical equation for this reaction. ……H2S + ……O2 → 2H2O + 2SO2 [2] (ii) Explain how this equation shows that hydrogen sulfide is oxidised. . …… . …… [1] [Total: 7]

Question

This question is about metals. (a) State three general physical properties common to most metals. 1 …… 2 …… 3 …… [3] (b) Metals are often used in the form of alloys. (i) State the meaning of the term alloy. . …… . …… [1] (ii) Explain in terms of their properties why alloys are used instead of pure metals. . …… [1] (iii) Stainless steel is an alloy. Give one use of stainless steel. . …… [1] (c) Place these metals in order of their reactivity with oxygen. copper magnesium potassium zinc Put the least reactive metal first. least reactive most reactive [2] (d) When 4.8 g of magnesium reacts with excess oxygen, 8.0 g of magnesium oxide is formed. Calculate the minimum mass of magnesium needed to produce 24.0 g of magnesium oxide. minimum mass = …… g [1] [Total: 9]

Question

This question is about acids, bases and salts. (a) Sodium hydroxide is a base. (i) Name the products formed when sodium hydroxide reacts with dilute nitric acid. . …… . …… [2] (ii) Describe the effect of sodium hydroxide on a named indicator. . …… . …… [2] (iii) Complete the word equation for the reaction of sodium hydroxide with ammonium chloride. sodium ammonium …… …… + + + water hydroxide chloride [2] (b) Describe how to prepare pure, dry crystals of the salt zinc sulfate from an aqueous solution of zinc sulfate. …… [2] (c) The rate of reaction of zinc powder with dilute sulfuric acid is found by measuring the increase in volume of hydrogen gas produced as time increases. Describe the effect, if any, of each of the following on the rate of this reaction. ● The reaction is carried out with large pieces of zinc instead of zinc powder. All other conditions stay the same. ● The reaction is carried out using a catalyst. All other conditions stay the same. ● The reaction is carried out with dilute sulfuric acid of a lower concentration. All other conditions stay the same. [3] [Total: 11]

Question

This question is about air. (a) The pie chart shows the proportions of the main gases in clean, dry air. gas G gas H (i) Name the gases G and H. gas G …… gas H …… [2] (ii) The graph shows how the volume of a sample of gas G changes as temperature increases. The pressure is kept constant. volume of gas G / cm3 temperature / C Describe how the volume of gas G changes as temperature increases. . …… [1] (iii) There is a small percentage of noble gases in the air. The noble gases are unreactive. Explain why the noble gases are unreactive in terms of their electronic structure. . …… . …… [1] (iv) Describe the arrangement and separation of the particles in a gas. arrangement …… separation . …… [2] (b) Two of the pollutants in air are oxides of nitrogen and lead compounds. (i) Give one effect of each of these pollutants on health. oxides of nitrogen …… lead compounds …… [2] (ii) Name two other pollutants present in air. State the source of each of these pollutants. pollutant 1 …… source of pollutant 1 …… pollutant 2 …… source of pollutant 2 …… [4] [Total: 12]

Question

The table shows some properties of four Group I elements. melting point boiling point element relative hardness / °C / °C lithium 181 1342 sodium 98 0.70 potassium 63 760 0.36 rubidium 39 686 0.22 (a) (i) Complete the table by estimating: ● the boiling point of sodium ● the relative hardness of lithium. [2] (ii) Predict the physical state of lithium at 200 °C. Give a reason for your answer. . …… . …… [2] (b) Potassium reacts with water. 2K + 2H2O → 2KOH + H2 Describe two observations when potassium reacts with water. 1 …… 2 …… [2] (c) Lithium is extracted by the electrolysis of molten lithium chloride. (i) Name a non-metal used to make the electrodes. . …… [1] (ii) Give one property, other than the conduction of electricity, that makes this substance suitable for use as an electrode. . …… [1] (iii) State the products of the electrolysis of molten lithium chloride at: the negative electrode (cathode) …… the positive electrode (anode). …… [2] (d) Lithium chloride conducts electricity when molten and when in aqueous solution. Give two other physical properties of lithium chloride that show it is an ionic compound. 1 …… 2 …… [2] [Total: 12]

Question

(a) The structures of four organic compounds, P, Q, R and S, are shown. P Q R S H H H H H H H H H H C C O H H C H H C C C H C C C H H O H H H H H H H H C C C H H O H Answer the following questions about these structures. Each structure may be used once, more than once or not at all. (i) State which structure, P, Q, R or S, has a carboxylic acid functional group. . …… [1] (ii) State which structure, P, Q, R or S, is in the same homologous series as ethane. . …… [1] (iii) State which structure, P, Q, R or S, decolourises aqueous bromine. . …… [1] (iv) Deduce the molecular formula of structure Q to show the number of carbon, hydrogen and oxygen atoms. . …… [1] (b) Structure S is produced by cracking petroleum fractions. (i) Complete the sentence using a word from the list. acids alkenes alcohols nitrogen During cracking, long-chain alkanes are converted to shorter chain alkanes and …… . [1] (ii) Cracking is an example of thermal decomposition. State the meaning of the term thermal decomposition. . …… . …… [2] (c) Link each petroleum fraction on the left to its use on the right. The first one has been done for you. fraction use refinery gas making chemicals naphtha bottled gas lubricating fraction jet fuel kerosene waxes and polishes [2] [Total: 9]

Question

This question is about chlorine and compounds of chlorine. (a) Chlorine is an element in Group VII of the Periodic Table. State the meaning of the term element. …… [1] (b) State one use of chlorine. …… [1] (c) Chlorine reacts with phosphorus to produce phosphorus(V) chloride. (i) Balance the equation for this reaction. ……P + ……Cl 2 → 2PCl 5 [2] (ii) This reaction is exothermic. State the meaning of the term exothermic. . …… [1] (d) Chlorine reacts with aqueous sodium bromide. (i) Complete the word equation for this reaction. sodium …… …… chlorine + + bromide [2] (ii) Describe a test for bromide ions. test . …… observations …… [2] (iii) When bromine is mixed with aqueous sodium chloride there is no reaction. Suggest in terms of chemical reactivity why there is no reaction. . …… [1] (e) A compound of chlorine has the formula C3H6Cl 2. Complete the table to calculate the relative molecular mass of C3H6Cl 2. relative atom number of atoms atomic mass carbon 3 12 3 × 12 = 36 hydrogen 1 chlorine 35.5 relative molecular mass = …… [2] [Total: 12] 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 20 rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon 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.).