Cambridge IGCSE Chemistry (9-1) 0971 — 2022 May/June Paper 3 · Variant 2

1 (a) A list of symbols and formulae is shown. Br – CH4 CO2 Cu2+ H2 K+ Na+ N2 O2 U Answer the following questions using these symbols or formulae. Each symbol or formula may be used once, more than once or not at all. State which symbol or formula represents: (i) a compound that is a product of respiration ....................................................................................................................................... [1] (ii) an ion that gives a lilac colour in a flame test ....................................................................................................................................... [1] (iii) a gas which is 21% of clean, dry air ....................................................................................................................................... [1] (iv) an element that has a radioactive isotope used as a source of energy ....................................................................................................................................... [1] (v) an ion formed when an atom gains an electron. ....................................................................................................................................... [1] (b) Complete the table to show the relative masses of a proton, a neutron and an electron. type of particle relative mass proton 1 neutron electron [2] (c) Choose the two correct statements about carbon dioxide. Tick (✓) two boxes. Carbon dioxide is a mixture of two elements. Carbon dioxide is an acidic oxide. Carbon dioxide has ionic bonding. Carbon dioxide has a giant covalent structure. There are three atoms in a molecule of carbon dioxide. [2] [Total: 9]

Mark scheme: 1(a)(i) CO2 1 1(a)(ii) K+ 1 1(a)(iii) O2 1 1(a)(iv) U 1 1(a)(v) Br- 1 1(b) neutron: 1 (1) electron: values between 0.000001 and 0.001 (1) 2 1(c) 2nd box ticked (1) 5th box ticked (1) 2

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2 The table shows the masses of some ions in a 1000 cm3 sample of toothpaste. mass of ion in 1000 cm3 name of ion formula of ion of toothpaste / g ammonium NH4+ 0.5 calcium Ca2+ 3.6 carbonate CO32– 2.5 chloride Cl – 0.9 fluoride F– 1.2 Mg2+ 0.2 phosphate PO43– 28.0 sodium Na+ 32.0 SO42– 10.4 tin(II) Sn2+ 0.3 (a) Answer these questions using only the information in the table. (i) State which positive ion has the lowest mass in 1000 cm3 of toothpaste. ....................................................................................................................................... [1] (ii) Name the compound that contains Mg2+ and SO42– ions. ....................................................................................................................................... [1] (iii) Calculate the mass of sodium ions in 200 cm3 of toothpaste. mass = .............................. g [1] (b) Describe a test for chloride ions. test ............................................................................................................................................. observations ............................................................................................................................... [2] (c) Toothpaste also contains glycerol. The structure of glycerol is shown. H H C O H H C O H H C O H H Deduce the formula of glycerol to show the number of atoms of carbon, hydrogen and oxygen. .............................................................................................................................................. [1] (d) Glycerol is an alcohol. Ethanol is also an alcohol. (i) Draw the structure of ethanol to show all of the atoms and all of the bonds. [1] (ii) Name the two products formed when ethanol undergoes complete combustion. ................................................................ and ��������������������������������������������������������������� [2] (iii) Give one use of ethanol. ....................................................................................................................................... [1] [Total: 10]

Mark scheme: 2(a)(i) 1 2(a)(ii) magnesium sulfate 1 2(a)(iii) 6.4 (g) 1 2(b) (add nitric acid and add) silver nitrate (1) white precipitate (1) 2 2(c) C3H8O3 1 Question Answer Marks 2(d)(i) H H │ │ H─C─C─O─H │ │ H H 1 2(d)(ii) carbon dioxide (1) water (1) 2 2(d)(iii) fuel / solvent 1

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3 This question is about Group I and Group VII elements. (a) Deduce the number of electrons, neutrons and protons in one atom of the isotope of potassium shown. 1940K number of electrons ................................................................................................................... number of neutrons .................................................................................................................... number of protons ...................................................................................................................... [3] (b) Complete the chemical equation for the reaction of potassium with water to form potassium hydroxide and a gas which pops with a lighted splint. 2K + .....H2O → 2KOH + .......... [2] (c) The table shows some properties of four Group I elements. melting point boiling point element relative hardness / °C / °C lithium 181 1342 5.0 sodium 883 .................... 0.7 potassium 63 760 .................... rubidium 39 686 0.2 (i) Complete the table by predicting: ● the melting point of sodium ● the relative hardness of potassium. [2] (ii) Predict the physical state of potassium at 100 °C. Give a reason for your answer. ............................................................................................................................................. ....................................................................................................................................... [2] (d) Aqueous bromine reacts with aqueous potassium iodide. Br2 + 2KI → 2KBr + I2 (i) Explain how this equation shows that bromine is more reactive than iodine. ............................................................................................................................................. ....................................................................................................................................... [1] (ii) State the colour of aqueous iodine. ....................................................................................................................................... [1] (e) Bromine is a diatomic molecule. State the meaning of the term diatomic. .............................................................................................................................................. [1] (f) Bromine liquid turns into a gas very easily at room temperature. Choose the word which best describes a substance that evaporates easily. Draw a circle around your chosen answer. conductor flammable malleable volatile [1] [Total: 13]

Mark scheme: 3(a) electrons: 19 (1) neutrons: 21 (1) protons: 19 (1) 3(b) 2 (H2O) (1) H2 (1) 2 3(c)(i) melting point of sodium: values between 65 and 178 (inclusive of these values) (1) hardness of potassium: values between 0.3 and 0.6 (inclusive of these values) (1) 2 3(c)(ii) liquid (1) 100 °C is higher than the melting point but lower than the boiling point / 100 °C is between the melting and boiling point / 100 °C is above the melting point and below the boiling point (1) 2 3(d)(i) bromine displaces iodine from potassium iodide / bromine replaces iodide in potassium iodide 1 3(d)(ii) brown 1 Question Answer Marks 3(e) (molecule) has two atoms 1 3(f) volatile 1

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4 This question is about acids and bases. (a) Name the type of chemical reaction which occurs when an acid reacts with a base. .............................................................................................................................................. [1] (b) Describe the colour of litmus in acidic and alkaline solutions. in acidic solution ......................................................................................................................... in alkaline solution ...................................................................................................................... [2] (c) Complete the word equation for the reaction of nitric acid with calcium hydroxide. nitric calcium ........................ ........................ + + acid hydroxide ........................ [2] (d) When nitric acid reacts with calcium hydroxide, the temperature of the reaction mixture increases. (i) Choose the word which best describes this reaction. Draw a circle around your chosen answer. decomposition endothermic exothermic oxidation [1] (ii) Complete the energy level diagram for the reaction of nitric acid with calcium hydroxide by writing the words: ● reactants ● products. energy progress of reaction [1] (e) Calcium hydroxide is slaked lime. Give one use of slaked lime. .............................................................................................................................................. [1] [Total: 8]

Mark scheme: 4(a) neutralisation 1 4(b) acidic: red / pink (1) alkaline: blue (1) 2 4(c) calcium nitrate (1) water (1) 2 4(d)(i) exothermic 1 4(d)(ii) reactants on top left horizontal line and products on bottom left horizontal line 1 4(e) treating acidic soil / neutralising acidic waste / flue gas desulfurisation / neutralising acidic soil 1

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5 This question is about aluminium. (a) The changes of state of aluminium are shown. A solid liquid aluminium aluminium aluminium gas B Name the changes of state represented by A and B. A ................................................................................................................................................. B ................................................................................................................................................. [2] (b) Use the kinetic particle model to describe the differences between solid aluminium and liquid aluminium in terms of: ● the arrangement of the particles ......................................................................................... .................................................................................................................................................... .................................................................................................................................................... ● the separation of the particles. ............................................................................................ .................................................................................................................................................... .................................................................................................................................................... [4] (c) Aluminium ore contains aluminium oxide. (i) Name the main ore of aluminium. ....................................................................................................................................... [1] (ii) Aluminium is extracted from aluminium oxide by electrolysis. Explain why aluminium is extracted by electrolysis and not by reduction with carbon. ............................................................................................................................................. ....................................................................................................................................... [1] (d) Aluminium can be used to reduce iron(III) oxide to iron. Fe2O3 + 2Al → 2Fe + Al 2O3 Describe how this equation shows that iron(III) oxide is reduced. .............................................................................................................................................. [1] (e) Aluminium is used for electric cables. State one other use of aluminium. Give a reason for this use in terms of the properties of aluminium. use of aluminium ........................................................................................................................ reason for this use ...................................................................................................................... .................................................................................................................................................... [2] (f) Deduce the electronic structure of aluminium. Use the Periodic Table to help you. .............................................................................................................................................. [1] [Total: 12]

Mark scheme: 5(a) A: melting (1) B: condensation / condensing (1) 2 Question Answer Marks 5(b) arrangement: solid: regular / in rows (1) liquid: irregular (1) separation: solid: close together / touching (1) liquid: close together / (some) touching (1) 4 5(c)(i) bauxite 1 5(c)(ii) aluminium is too reactive / aluminium is above carbon in the reactivity series 1 5(d) oxygen removed from iron oxide / iron oxide loses oxygen 1 5(e) use (1) property related to the use (1) e.g. aircraft/ aeroplane (1) low density / strength (1) food containers / food cans / window frames (1) resistance to corrosion (1) Saucepans/ pans (1) Good conductor of heat (1) 2 5(f) 2,8,3 1

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6 (a) The structures of four organic compounds, C, D, E and F, are shown. C D H H H H H H H O H C C C H C C C C C H O H H H H H H H H E F H H H H H H C C C H C C H H H H H (i) State which two of the compounds, C, D, E and F, are in the same homologous series. ................................................................ and ��������������������������������������������������������������� [1] (ii) State which compound, C, D, E or F, is the monomer used to make poly(ethene). ....................................................................................................................................... [1] (iii) State which compound, C, D, E or F, is a carboxylic acid. ....................................................................................................................................... [1] (b) Petroleum is a mixture of hydrocarbons, which can be separated into fractions. Describe how petroleum is separated into fractions to include: ● the name of the process used to separate the fractions .................................................................................................................................................... ● how this process separates the different fractions. .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... [4] (c) Complete the table to show the name and uses of some petroleum fractions. name of fraction use of fraction naphtha diesel oil (gas oil) making roads [3] [Total: 10]

Mark scheme: 6(a)(i) D and E 1 6(a)(ii) F 1 6(a)(iii) C 1 Question Answer Marks 6(b) (fractional) distillation (1) AND 1 mark each for any three of:  petroleum vaporised / heated / turned into a gas  temperature gradient in column / column hotter at bottom / colder at top  smaller hydrocarbons go further up the column / larger hydrocarbons stay near the bottom of the column  different boiling points of fractions / alkanes / molecules / hydrocarbons  fractions / molecules / hydrocarbons come off at different heights in the column 4 6(c) naphtha: making chemicals (1) diesel oil: fuel for cars / fuel for vehicles (1) making roads: bitumen (1) 3

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7 This question is about sodium and compounds of sodium. (a) Sodium is a metal in Group I of the Periodic Table. (i) Give two physical properties of all metals. 1 .......................................................................................................................................... 2 .......................................................................................................................................... [2] (ii) Give one physical property of Group I metals that is different from most other metals and state how it is different. ............................................................................................................................................. ....................................................................................................................................... [1] (b) Sodium reacts with oxygen to form sodium oxide, Na2O. Complete the chemical equation for this reaction. .....Na + O2 → .....Na2O [2] (c) The diagram shows the apparatus used to electrolyse molten sodium iodide. power supply – + (i) Complete the diagram by labelling: ● the electrolyte ● the cathode. [2] (ii) Name the products formed at each electrode. positive electrode ................................................................................................................ negative electrode ............................................................................................................... [2] (d) A compound of sodium has the formula Na2S2O3. Complete the table to calculate the relative molecular mass of Na2S2O3. relative atom number of atoms atomic mass sodium 2 23 2 × 23 = 46 sulfur 32 oxygen 16 relative molecular mass = .............................. [2] [Total: 11]

Mark scheme: 7(a)(i) 1 mark each for any two of:  conduct electricity / conduct heat (1)  malleable (1)  ductile (1)  shiny / lustrous (1) 7(a)(ii) density is low(er) / melting point is low(er) / soft 1 7(b) 4 (Na) (1) 2 (Na2O) (1) 2 7(c)(i) electrolyte labelled (1) negative electrode labelled cathode (1) 2 Question Answer Marks 7(c)(ii) positive electrode: iodine (1) negative electrode: sodium (1) 2 7(d) 158 (2) if two marks not scored, allow 1 mark for S = 2  32 / 64 OR O = 3  16 / 48 2

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8 A student investigates the reaction of small pieces of calcium carbonate with dilute hydrochloric acid. The hydrochloric acid is in excess. CaCO3 + 2HCl → CaCl 2 + CO2 + H2O The rate of reaction is found by measuring the volume of carbon dioxide gas produced as time increases. The results are shown on the graph. 60 50 40 volume of carbon dioxide / cm3 30 20 10 0 0 10 20 30 40 50 60 70 time / s (a) Deduce the volume of carbon dioxide gas at 35 s. volume = .............................. cm3 [1] (b) The experiment is repeated at a higher temperature. All other conditions stay the same. Draw a line on the grid to show how the volume of carbon dioxide gas produced changes as time increases. [2] (c) Describe the effect each of the following has on the rate of reaction of calcium carbonate with dilute hydrochloric acid. All other conditions stay the same. ● The reaction is carried out using a higher concentration of hydrochloric acid. .................................................................................................................................................... ● The reaction is carried out using powdered calcium carbonate. .................................................................................................................................................... [2] (d) When 0.11 g of calcium carbonate is used, 25 cm3 of carbon dioxide gas is produced. Calculate the mass of calcium carbonate needed to produce 100 cm3 of carbon dioxide gas. mass of calcium carbonate = .............................. g [1] (e) State one use of calcium carbonate. .............................................................................................................................................. [1] [Total: 7]

Mark scheme: 8(a) 44 (cm3) 1 8(b) initial gradient steeper starting at 0-0 point (1) line ends at same final volume (1) 2 8(c) concentration: rate increases / reaction faster / rate higher / reaction speeds up (1) smaller pieces: rate increases / reaction faster / rate higher / reaction speeds up (1) 2 8(d) 0.44 (g) 1 8(e) making iron / making cement 1

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