Rate of reaction — Paper 3 · IGCSE Science - Combined 0653

2 A student reacts dilute hydrochloric acid with a solid metal carbonate, as shown in Fig. 2.1. thermometer gas bubbles solid metal dilute hydrochloric acid carbonate Fig. 2.1 (a) (i) Name the gas produced in this reaction. … [1] (ii) The student observes that the temperature increases. State the type of reaction that results in a temperature increase. … [1] (iii) Describe the change in the pH number of the solution during the reaction. … [1] (iv) The student records the time taken for the reaction to stop. Suggest how she knows that the reaction has stopped. … … [1] (v) Some solid metal carbonate is left over after the reaction has stopped. State one method used to separate the unreacted solid metal carbonate from the mixture. … [1] (b) The student changes the concentration of the acid and then repeats the reaction. (i) Describe the effect of using acid with a lower concentration on the rate of the reaction. … [1] (ii) Suggest one other way of changing the rate of the reaction. … [1] (c) Describe a test to show that the acid used contains chloride ions. State the change that is observed. test … observation … [2]

9 marks

Mark scheme: 2(a)(i) carbon dioxide / CO2 ; 1 2(a)(ii) exothermic ; 1 2(a)(iii) increase / goes to 7 ; 1 2(a)(iv) fizzing / bubbles / gas / CO2 stops / no more ; 1 2(a)(v) filter(ing) / filtration ; 1 Question Answer Marks 2(b)(i) (rate is) less / reduced ; 1 2(b)(ii) (change) temperature / (use a) catalyst (change) surface area / particle size / stirring; 1 2(c) (test) (add) silver nitrate (soln) ; (observation) white_solid / precipitate ; 2

This question in 0653/32 Feb/March 2017

5 A student investigates the reaction between dilute sulfuric acid and copper(II) carbonate powder. The apparatus she uses is shown in Fig. 5.1. gas syringe copper(II) carbonate dilute sulfuric acid powder Fig. 5.1 The reaction produces a gas which is collected in the gas syringe. (a) (i) Name the gas and the salt which are produced in this reaction. gas … salt … [2] (ii) Describe the pH change, if any, of the reaction mixture. Name this type of reaction. pH change … reaction type … [2] (b) The student records the volume of gas in the syringe for 10 minutes. Her results are shown in Fig. 5.2. volume of gas 0 1 2 3 4 5 6 7 8 9 10 time / minutes Fig. 5.2 Suggest why the reaction stops at 4 minutes. … … [1] (c) The student repeats the experiment using the same mass of powdered copper(II) carbonate and the same volume of dilute sulfuric acid. Suggest one change that the student can make to decrease the time taken for the reaction to stop. … [1] (d) The formula of sulfuric acid is H2SO4. (i) State the number of different elements and the total number of atoms shown in this formula. number of elements … number of atoms … [2] (ii) Describe a chemical test for sulfate ions and state the positive result. test … … result … [2]

10 marks

Mark scheme: 5(a)(i) carbon dioxide ; copper sulfate ; 2 5(a)(ii) increases ; salt making / neutralisation ; 2 5(b) runs out of / no more (sulfuric) acid / copper carbonate / powder ; 1 5(c) higher temperature / more concentrated (acid) / decrease particle size (of powder) / agitate the flask ; 1 5(d)(i) three / 3 ; seven / 7 ; 2 5(d)(ii) (acidified) barium ions / barium nitrate (soln) ; (result) white ppt / white solid ; 2

This question in 0653/31 May/June 2017

2 A student places four pieces of metal, at the same time, into separate beakers containing dilute hydrochloric acid, HCl. The four metals react with the acid to produce the same gas, but at different rates. The gas is collected in test-tubes, as shown in Fig. 2.1. gas bubbles of gas dilute metalhydrochloric acid metal A metal B metal C metal D Fig. 2.1 The four metals are calcium, iron, magnesium, and zinc. (a) (i) Using the information in Fig. 2.1 and your knowledge of the reactivity series, identify metals A, B, C and D. metal A … metal B … metal C … metal D … [2] (ii) Name the gas made in the reaction between magnesium and dilute hydrochloric acid. … [1] (iii) State the effect of increasing the temperature of the acid on the rate of reaction with the metals. … [1] (iv) Suggest one other way of changing the rate of reaction. … [1] (b) When iron reacts with dilute hydrochloric acid, a solution of an iron salt is made. The student thinks that this salt contains iron(II) ions. Another student thinks that the salt contains iron(III) ions. They add dilute sodium hydroxide solution to a sample of the iron salt solution. Describe the observations that are expected for iron(II) ions and for iron(III) ions. iron(II) ions … iron(III) ions … [2] (c) Iron is a transition metal. (i) Suggest two properties of iron that are not properties of Group I metals. 1. … 2. … [2] (ii) Explain why iron is used in the form of alloys, rather than as pure iron, for kitchen knives. … … … [1]

10 marks

Mark scheme: 2(a)(i) (metal A) calcium / Ca (metal B) magnesium / Mg (metal C) zinc / Zn (metal D) iron / Fe ;; 2 2(a)(ii) hydrogen ; 1 2(a)(iii) increases (rate) ; 1 2(a)(iv) any one from change / increase / decrease concentration / surface area / (solid) particle size ; use / add a catalyst ; max 1 2(b) (iron(II) ions) green ppt / solid ; (iron(III) ions) brown ppt / solid ; 2 2(c)(i) Any two from high_density ; high_melting point ; (form) coloured compounds ; catalysts ; 2 Question Answer Marks 2(c)(ii) (alloys are) harder / more resistant to wear / more resistant to corrosion ; 1

This question in 0653/32 Oct/Nov 2017

8 (a) Molten lead(II) bromide is broken down into simpler substances using the apparatus shown in Fig. 8.1. low voltage d.c.supply … … – + molten lead (II) bromide Fig. 8.1 (i) Use the names of the electrodes to complete Fig. 8.1. [2] (ii) Describe the appearance of the substance that forms at the positive electrode. … [1] (b) Copper is extracted from copper oxide by heating with carbon. The equation for this reaction is copper oxide + carbon copper + carbon dioxide. State whether the copper oxide is oxidised or reduced during this reaction. Explain your answer. … … [1] (c) Copper, Cu, does not react with water. Calcium, Ca, reacts rapidly with water. Magnesium, Mg, reacts slowly with water. Potassium, K, reacts very rapidly with water. Place these four metals in order of reactivity, from most to least reactive. … most reactive … … … least reactive [2] (d) A student adds excess magnesium to dilute hydrochloric acid. (i) State two changes that the student can make to increase the rate of this reaction. 1. … 2. … [2] (ii) Identify the salt produced during this reaction. … [1] (iii) After the reaction finishes, the student removes the unreacted magnesium from the solution that has formed. Name the separation technique that the student uses. … [1]

10 marks

Mark scheme: 8(a)(i) (left) cathode ; (right) anode ; 2 8(a)(ii) orange / brown gas ; 1 8(b) (reduced) oxygen is removed ; 1 8(c) K Ca Mg Cu ;; 2 8(d)(i) any two from heat / increase temperature ; increase surface area of magnesium ; increase concentration of acid ; use / add a catalyst ; 2 8(d)(ii) magnesium chloride ; 1 8(d)(iii) filter / filtration ; 1

This question in 0653/33 Oct/Nov 2017

5 (a) A student adds magnesium powder to dilute hydrochloric acid. She then uses a balance to investigate the rate of this reaction, as shown in Fig. 5.1. cotton wool conical flask dilute hydrochloric acid magnesium powder 124.57g balance Fig. 5.1 (i) Describe the change in the mass, if any, of the conical flask and its contents. Explain your answer. change … explanation … … [2] (ii) Describe one change that can be made to decrease the rate of this reaction. … … [1] (iii) Predict the effect of using calcium, rather than magnesium, on the rate of reaction. Explain your answer using ideas about reactivity. effect … explanation … … [2] (b) Magnesium is produced by the electrolysis of magnesium chloride. (i) State the energy source used in electrolysis. … [1] (ii) Predict the type of bond present in magnesium chloride. … [1] (iii) Magnesium chloride is produced when one atom of magnesium combines with two atoms of chlorine. Predict the formula of magnesium chloride. … [1] (iv) Magnesium is also produced by heating magnesium oxide with silicon. In this process, oxygen is removed from magnesium oxide. State the type of reaction that leads to the loss of oxygen from a substance. … [1]

9 marks

Mark scheme: 5(a)(i) (decreases) no mark gas produced / released (during reaction) ; (gas goes) to the surroundings / (gas) leaves flask ; 2 5(a)(ii) lower temperature / lower (acid) concentration / use lumps (instead of powder) ; 1 5(a)(iii) increases ; calcium is more reactive (than magnesium) ; 2 5(b)(i) electricity ; 1 5(b)(ii) ionic ; 1 5(b)(iii) MgCl2 ; 1 5(b)(iv) reduction ; 1 Que estion Answer Ma arks

This question in 0653/32 May/June 2018

5 (a) A student adds magnesium powder to dilute hydrochloric acid. She then uses a balance to investigate the rate of this reaction, as shown in Fig. 5.1. cotton wool conical flask dilute hydrochloric acid magnesium powder 124.57g balance Fig. 5.1 (i) Describe the change in the mass, if any, of the conical flask and its contents. Explain your answer. change … explanation … … [2] (ii) Describe one change that can be made to decrease the rate of this reaction. … … [1] (iii) Predict the effect of using calcium, rather than magnesium, on the rate of reaction. Explain your answer using ideas about reactivity. effect … explanation … … [2] (b) Magnesium is produced by the electrolysis of magnesium chloride. (i) State the energy source used in electrolysis. … [1] (ii) Predict the type of bond present in magnesium chloride. … [1] (iii) Magnesium chloride is produced when one atom of magnesium combines with two atoms of chlorine. Predict the formula of magnesium chloride. … [1] (iv) Magnesium is also produced by heating magnesium oxide with silicon. In this process, oxygen is removed from magnesium oxide. State the type of reaction that leads to the loss of oxygen from a substance. … [1]

9 marks

Mark scheme: 5(a)(i) (decreases) no mark gas produced / released (during reaction) ; (gas goes) to the surroundings / (gas) leaves flask ; 2 5(a)(ii) lower temperature / lower (acid) concentration / use lumps (instead of powder) ; 1 5(a)(iii) increases ; calcium is more reactive (than magnesium) ; 2 5(b)(i) electricity ; 1 5(b)(ii) ionic ; 1 5(b)(iii) MgCl2 ; 1 5(b)(iv) reduction ; 1 Que estion Answer Ma arks

This question in 0653/33 May/June 2018

8 (a) When zinc oxide is heated with carbon, zinc and carbon dioxide are formed. (i) State the type of chemical reaction that occurs when zinc loses oxygen. … [1] (ii) Suggest one effect on the reaction between zinc oxide and carbon of using a lower temperature. … [1] (iii) Explain why argon, a Group VIII gas, does not react with zinc oxide. … [1] (b) When aluminium oxide is heated with carbon, there is no reaction. Explain why aluminium oxide does not react with carbon. Use ideas about the reactivity series in your answer. … … [1] (c) (i) Name the ore from which aluminium is extracted. … [1] (ii) State the method used to extract aluminium. … [1] (d) Iron is a transition element. Sodium is a Group I element. Describe one difference and one similarity between the physical properties of iron and of sodium. difference … … similarity … … [2] (e) Recycled metals can cost less than metals extracted from their ores. Suggest one other reason why metals are recycled. … … [1] [Total: 9]

9 marks

Mark scheme: 8(a)(i) reduction ; 1 8(a)(ii) slower (reaction) ; 1 8(a)(iii) argon / noble gases / Group VIII gases have full outer electron shell ; 1 8(b) aluminium is more reactive (than carbon) ; 1 8(c)(i) bauxite ; 1 8(c)(ii) electrolysis ; 1 8(d) (difference) density / melting point / hardness / strength ; (similarity) (electrical / heat) conductivity ; 2 8(e) metals/ores are running out/finite / no need to mine / does not go into landfill ; 1

This question in 0653/33 May/June 2019

2 A student investigates the rate of reaction between a piece of magnesium and excess dilute hydrochloric acid. (a) During this reaction, hydrogen is produced. (i) Complete the equation for this reaction. + + hydrogen [2] (ii) Describe the chemical test for hydrogen and state the positive result. test … result … [2] (b) The reaction between magnesium and dilute hydrochloric acid is exothermic. State the meaning of exothermic. … … [1] (c) (i) Describe the effect of increasing the concentration of the acid on the rate of reaction. … [1] (ii) Describe the effect of decreasing the temperature of the acid on the rate of reaction. … [1] (d) The student repeats the experiment but uses a piece of zinc instead of a piece of magnesium. The piece of zinc has the same surface area as the piece of magnesium. Suggest the effect that using zinc instead of magnesium has on the rate of the reaction. Explain your answer. effect … explanation … … [2] [Total: 9]

9 marks

Mark scheme: 2(a)(i) magnesium + hydrochloric acid → magnesium chloride + (hydrogen) reactants ; magnesium chloride ; 2(a)(ii) (test) lighted splint ; (result) burns with a squeaky ‘pop’ ; 2 2(b) (thermal) energy / heat, is, released / given out ; 1 2(c)(i) rate increases ; 1 2(c)(ii) rate decreases ; 1 2(d) (effect) rate, decreases / reduces ; (explanation) zinc is less reactive (than magnesium) ; 2

This question in 0653/33 Oct/Nov 2020

8 (a) A student reacts a piece of magnesium with dilute hydrochloric acid, as shown in Fig. 8.1. A funnel holds the magnesium under a measuring cylinder to collect the gas formed. gas measuring cylinder dilute hydrochloric acid magnesium funnel Fig. 8.1 (i) State one other piece of apparatus that the student needs to use to determine the rate of this reaction. … [1] (ii) Suggest one change that increases the rate of this reaction. … [1] (iii) The student repeats the experiment under the same conditions, using the same mass of zinc instead of magnesium. State and explain the effect of this change on the rate of reaction. effect … explanation … [1] (b) Brass is a mixture of zinc and copper. (i) State the general name of mixtures such as brass that contain different metals. … [1] (ii) Suggest why brass, and not pure copper, is used to make coins. … … [1] (c) Some copper compounds are used as catalysts. Name the collection of metals in the Periodic Table that includes copper. … [1] (d) Copper is extracted from copper oxide using carbon. (i) Describe one condition needed for this process. … [1] (ii) State and explain whether copper is oxidised or reduced in this process. copper is … explanation … … [1] [Total: 8]

8 marks

Mark scheme: 8(a)(i) stop-clock ; 1 Question Answer Marks 8(a)(ii) any one from: increase temperature ; increase concentration (of acid) ; increase surface area (of Mg) / use Mg powder / use smaller pieces ; add a catalyst ; 1 8(a)(iii) effect: decrease / slower (rate) AND explanation: zinc is less reactive (than magnesium) ORA ; 1 8(b)(i) alloy ; 1 8(b)(ii) brass is, stronger / harder / less malleable / hardwearing / durable / corrodes or oxidises less / doesn’t go green ; 1 8(c) transition (elements / metals) ; 1 8(d)(i) high temperature ; 1 8(d)(ii) copper is: reduced AND explanation: (copper) loses, oxygen / O ; 1

This question in 0653/31 May/June 2021

8 A student investigates the rate of the reaction between lumps of calcium carbonate and dilute hydrochloric acid. The student uses the pieces of apparatus shown in Fig. 8.1. apparatus X dilute calcium carbonate hydrochloric acid Fig. 8.1 (a) State the name of apparatus X. … [1] (b) Suggest one piece of apparatus that is not shown in Fig. 8.1 which the student needs to investigate the rate of this reaction. … [1] (c) Complete the word equation for this reaction. calcium hydrochloric + + + carbonate acid [2] (d) The student repeats the experiment using the same mass of calcium carbonate and the same volume of dilute hydrochloric acid. (i) Suggest one change that the student makes to the calcium carbonate to increase the rate of the reaction. … [1] (ii) Suggest one change that the student makes to the hydrochloric acid to increase the rate of the reaction. … [1] (e) A type of calcium atom has the symbol shown. 3620Ca (i) Deduce the number of neutrons in this atom. … [1] (ii) Deduce the number of electrons in one Ca2+ ion. … [1] [Total: 8]

8 marks

Mark scheme: 8(a) (gas) syringe ; 1 8(b) stop-watch ; 1 8(c) calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide calcium chloride / water AND carbon dioxide ; all correct ; 2 8(d)(i) (use) powder / crush (lumps) ; 1 8(d)(ii) (use) more concentrated / increase temperature ; 1 8(e)(i) 16 ; 1 8(e)(ii) 18 ; 1

This question in 0653/32 Oct/Nov 2021

8 A student investigates the rate of the reaction between lumps of calcium carbonate and dilute hydrochloric acid. The student uses the pieces of apparatus shown in Fig. 8.1. apparatus X dilute calcium carbonate hydrochloric acid Fig. 8.1 (a) State the name of apparatus X. … [1] (b) Suggest one piece of apparatus that is not shown in Fig. 8.1 which the student needs to investigate the rate of this reaction. … [1] (c) Complete the word equation for this reaction. calcium hydrochloric + + + carbonate acid [2] (d) The student repeats the experiment using the same mass of calcium carbonate and the same volume of dilute hydrochloric acid. (i) Suggest one change that the student makes to the calcium carbonate to increase the rate of the reaction. … [1] (ii) Suggest one change that the student makes to the hydrochloric acid to increase the rate of the reaction. … [1] (e) A type of calcium atom has the symbol shown. 3620Ca (i) Deduce the number of neutrons in this atom. … [1] (ii) Deduce the number of electrons in one Ca2+ ion. … [1] [Total: 8]

8 marks

Mark scheme: 8(a) (gas) syringe ; 1 8(b) stop-watch ; 1 8(c) calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide calcium chloride / water AND carbon dioxide ; all correct ; 2 8(d)(i) (use) powder / crush (lumps) ; 1 8(d)(ii) (use) more concentrated / increase temperature ; 1 8(e)(i) 16 ; 1 8(e)(ii) 18 ; 1

This question in 0653/33 Oct/Nov 2021

2 (a) Potassium, K, and fluorine, F, are both elements. The electronic structure of a potassium atom and of a fluorine atom are shown in Fig. 2.1. K F potassium fluorine atom atom Fig. 2.1 Potassium and fluorine react exothermically to form the compound potassium fluoride. (i) Complete Fig. 2.2 to show the electronic structure of a potassium ion and of a fluoride ion in potassium fluoride. K F potassium fluoride ion ion Fig. 2.2 [2] (ii) State what is meant by the term exothermic. … … [1] (iii) State what is meant by the terms element and compound. element … … compound … … [2] (b) A student investigates the rate of reaction between solid potassium oxide and dilute sulfuric acid. (i) State the name of the salt that forms in this reaction. … [1] (ii) Suggest two ways of increasing the rate of this reaction. 1 … 2 … [2] (c) Potassium carbonate reacts with dilute hydrochloric acid to make potassium chloride and a gas and one other product. Complete the word equation for this reaction. dilute potassium potassium + hydrochloric + + carbonate chloride acid [2] [Total: 10]

10 marks

Mark scheme: 2(a)(i) potassium any symbols showing 2,8,8 ; 2 fluoride any symbols showing 2,8 ; 2(a)(ii) (a reaction in which) thermal / heat, energy is released ; 1 2(a)(iii) element (contains) one type of atom (only) ; 2 compound two or more elements chemically, combined / bonded / joined together ; 2(b)(i) potassium sulfate ; 1 2(b)(ii) any two from: 2 increase temperature ; decrease particle size (of solid / potassium oxide) ; increase concentration (of acid) ; add a catalyst ; 2(c) 2 carbon dioxide ; water ;

This question in 0653/31 Oct/Nov 2022

5 Copper is a transition element. (a) State two properties of transition elements that are not properties of Group I metals. 1 … 2 … [2] (b) Copper is extracted from copper oxide by heating with carbon. Identify the greenhouse gas formed in this process. … [1] (c) Copper is slowly oxidised by oxygen when it is left in air. The reaction equation is shown. 2Cu(s) + O2(g) 2CuO(s) (i) State the meaning of the term oxidised. … … [1] (ii) Suggest one change that increases the rate of this reaction. … [1] (d) (i) State the percentage of oxygen in clean air. … % [1] (ii) Suggest the percentage of argon in clean air. … % [1] (iii) State why argon does not react with copper. … … [1] [Total: 8]

8 marks

Mark scheme: 5(a) any two from: 2 high density ; high melting point ; (forms) coloured compounds ; (can) act as catalysts (as element or compound) ; 5(b) carbon dioxide / CO2 ; 1 5(c)(i) (it) gains oxygen ; 1 5(c)(ii) any one from: 1 increase / higher, temperature / heat (it) ; increase surface area ; 5(d)(i) 21(%) ; 1 5(d)(ii) less than 1(%) ; 1 5(d)(iii) argon is inert / argon is a noble gas / argon atoms have full outer shell ; 1

This question in 0653/32 Feb/March 2023

8 Copper(II) sulfate, CuSO4, can be made by reacting copper(II) oxide, CuO, with a dilute acid. (a) (i) Complete the word equation for the formation of copper(II) sulfate from copper(II) oxide. copper(II) ……………... copper(II) + + ………………. oxide acid sulfate [1] (ii) State two ways of increasing the rate of this reaction. 1 … 2 … [2] (b) (i) State the colour observed in the flame test of copper(II) ions, Cu2+. … [1] (ii) State the test for sulfate ions and the observation for a positive result. test … … observation … [2] (c) Copper atoms can have different numbers of neutrons. One atom of copper is represented as shown. 63 29Cu Deduce the number of electrons and neutrons in this atom. electrons … neutrons … [2] [Total: 8]

8 marks

Mark scheme: 8(a)(i) sulfuric (acid) AND water ; 1 Question Answer Marks 8(a)(ii) any two from: increase temperature ; increase surface area (of solid / CuO) ; increase concentration (of acid) ; 2 8(b)(i) blue-green ; 1 8(b)(ii) (test) aqueous barium nitrate ; (observation) white, precipitate / solid ; 2 8(c) (electrons) 29 ; (neutrons) 34 ; 2

This question in 0653/31 May/June 2023

2 A student investigates the reactions of four metals with dilute hydrochloric acid, HCl. (a) In the first experiment, the student adds a piece of each metal to separate test-tubes of dilute hydrochloric acid. The concentration and temperature of the acid are the same in each test-tube. The size of each piece of metal is the same, and the pieces of metal are added to the acid at the same time. The student observes bubbles of gas being produced in three of the test-tubes, as shown in Fig. 2.1. dilute hydrochloric acid bubble of gas copper zinc metal X metal Y Fig. 2.1 (i) State the name of the gas produced in this investigation. … [1] (ii) State the name of the salt made in the reaction between zinc and dilute hydrochloric acid. … [1] (iii) Explain why bubbles of gas are produced in the test-tube containing zinc, but no bubbles of gas are produced in the test-tube containing copper. … … [1] (iv) Suggest the identities of metal X and metal Y. Choose from the list of metals. aluminium calcium iron magnesium metal X … metal Y … [1] (b) In the second experiment, the student uses the apparatus shown in Fig. 2.2 to investigate the rate of reaction of zinc with dilute hydrochloric acid. gas W water dilute hydrochloric acid zinc Fig. 2.2 (i) State the name of the piece of apparatus labelled W. … [1] (ii) State one other piece of apparatus, not shown in Fig. 2.2, that the student uses to investigate the rate of this reaction. … [1] (iii) Suggest one way the student can increase the rate of this reaction. … … [1] (iv) When zinc reacts with dilute hydrochloric acid, an aqueous zinc salt is formed. This salt contains zinc ions, Zn2+. State a chemical test for zinc ions, Zn2+, and give the observation for a positive result. test … … observation … … [2] [Total: 9]

9 marks

Mark scheme: 2(a)(i) hydrogen ; 1 2(a)(ii) zinc chloride ; 1 2(a)(iii) zinc is more reactive (than copper / hydrogen) ORA ; 1 2(a)(iv) metal X: calcium / aluminium / magnesium ; 1 metal Y: iron ; 2(b)(i) measuring cylinder ; 1 2(b)(ii) stop-watch / timer ; 1 2(b)(iii) any one from: 1 increase concentration (of acid) ; increase temperature ; increase surface area of zinc / use smaller zinc pieces ; use a catalyst ; 2(b)(iv) test: aqueous sodium hydroxide / aqueous ammonia ; 2 result: white precipitate / solid AND solid is soluble in excess solution ;

This question in 0653/32 Oct/Nov 2023

2 A student investigates the reactions of four metals with dilute hydrochloric acid, HCl. (a) In the first experiment, the student adds a piece of each metal to separate test-tubes of dilute hydrochloric acid. The concentration and temperature of the acid are the same in each test-tube. The size of each piece of metal is the same, and the pieces of metal are added to the acid at the same time. The student observes bubbles of gas being produced in three of the test-tubes, as shown in Fig. 2.1. dilute hydrochloric acid bubble of gas copper zinc metal X metal Y Fig. 2.1 (i) State the name of the gas produced in this investigation. … [1] (ii) State the name of the salt made in the reaction between zinc and dilute hydrochloric acid. … [1] (iii) Explain why bubbles of gas are produced in the test-tube containing zinc, but no bubbles of gas are produced in the test-tube containing copper. … … [1] (iv) Suggest the identities of metal X and metal Y. Choose from the list of metals. aluminium calcium iron magnesium metal X … metal Y … [1] (b) In the second experiment, the student uses the apparatus shown in Fig. 2.2 to investigate the rate of reaction of zinc with dilute hydrochloric acid. gas W water dilute hydrochloric acid zinc Fig. 2.2 (i) State the name of the piece of apparatus labelled W. … [1] (ii) State one other piece of apparatus, not shown in Fig. 2.2, that the student uses to investigate the rate of this reaction. … [1] (iii) Suggest one way the student can increase the rate of this reaction. … … [1] (iv) When zinc reacts with dilute hydrochloric acid, an aqueous zinc salt is formed. This salt contains zinc ions, Zn2+. State a chemical test for zinc ions, Zn2+, and give the observation for a positive result. test … … observation … … [2] [Total: 9]

9 marks

Mark scheme: 2(a)(i) hydrogen ; 1 2(a)(ii) zinc chloride ; 1 2(a)(iii) zinc is more reactive (than copper / hydrogen) ORA ; 1 2(a)(iv) metal X: calcium / aluminium / magnesium ; 1 metal Y: iron ; 2(b)(i) measuring cylinder ; 1 2(b)(ii) stop-watch / timer ; 1 2(b)(iii) any one from: 1 increase concentration (of acid) ; increase temperature ; increase surface area of zinc / use smaller zinc pieces ; use a catalyst ; 2(b)(iv) test: aqueous sodium hydroxide / aqueous ammonia ; 2 result: white precipitate / solid AND solid is soluble in excess solution ;

This question in 0653/33 Oct/Nov 2023

8 (a) Solid zinc and dilute sulfuric acid react to form zinc sulfate and hydrogen gas. Zn + H2SO4 ZnSO4 + H2 (i) A student measures and controls the temperature, the volume and the concentration of the acid. State two other measurements that the student needs to make to investigate the rate of this reaction. 1 … 2 … [2] (ii) Describe what happens to the pH number of the reaction mixture during the reaction. … [1] (b) Dilute sulfuric acid is electrolysed using the apparatus shown in Fig. 8.1. low voltage d.c. power supply negative positive electrode electrode dilute sulfuric acid Fig. 8.1 (i) State the name of the negative electrode. … [1] (ii) Identify the product that forms at the positive electrode. … [1] [Total: 5]

5 marks

Mark scheme: 8(a)(i) time ; and any one of: volume of gas / H2/ total mass / mass of hydrogen ; 2 8(a)(ii) (pH number) increases ; 1 8(b)(i) cathode ; 1 8(b)(ii) oxygen / O2 ; 1

This question in 0653/31 May/June 2024

2 A student investigates the reaction of magnesium with excess dilute hydrochloric acid using the apparatus shown in Fig. 2.1. excess dilute hydrochloric acid magnesium Fig. 2.1 The equation for the reaction is shown. Mg + 2HCl MgCl2 + H2 (a) The student repeats the experiment at the same temperature, using the same volume of acid with a lower concentration. Describe the effect of this change on the rate of the reaction. … [1] (b) Describe the effect of dilute hydrochloric acid on litmus paper. … [1] (c) Describe a chemical test for hydrogen gas. State the observation for a positive result. test … observation … … [2] (d) One alloy contains copper and magnesium. (i) State what is meant by an alloy. … … [1] (ii) Copper is extracted from copper oxide by heating with carbon. Magnesium cannot be extracted from magnesium oxide by heating with carbon. Explain these observations. copper … … magnesium … … [2] [Total: 7]

7 marks

Mark scheme: 2(a) (rate of reaction) decreases / slows down ; 1 2(b) (turns blue litmus paper) red ; 1 2(c) (test) lighted splint ; (observation) ‘pops’ ; 2 2(d)(i) a mixture of a metal with another element(s) ; 1 2(d)(ii) (copper) is less reactive than carbon ORA ; (magnesium) is more reactive than carbon ORA ; 2

This question in 0653/32 May/June 2024

2 A student investigates the rate of reaction between solid magnesium carbonate and dilute hydrochloric acid. Fig. 2.1 shows the apparatus. bubbles of gas syringe carbon dioxide gas conical flask lumps of solid magnesium carbonate dilute hydrochloric acid Fig. 2.1 (a) Complete the word equation for the reaction shown in Fig. 2.1. carbon + + water + dioxide [2] (b) The student investigates this reaction using three different concentrations, A, B and C, of dilute hydrochloric acid. All other variables are kept constant. Fig. 2.2 shows the volume of carbon dioxide gas produced over a period of 100 s. 60 50 A 40 B volume of C carbon dioxide gas 30 produced / cm3 20 10 0 0 10 20 30 40 50 60 70 80 90 100 time / s Fig. 2.2 (i) Identify the time at which the acid with concentration B stops reacting. time = … s [1] (ii) Use Fig. 2.2 to identify which concentration, A, B or C, is the lowest concentration of dilute hydrochloric acid. Explain your answer. concentration … explanation … … … [2] (iii) Changing the concentration of dilute hydrochloric acid affects the rate of reaction. State two other ways of affecting the rate of reaction. 1 … 2 … [2] (c) The reaction between dilute hydrochloric acid and magnesium carbonate produces water. (i) State the name of the type of chemical bonding in a water molecule. … [1] (ii) Complete the dot-and-cross diagram in Fig. 2.3 to show the bonding in a water molecule, H2O. Show all the outer-shell electrons. O H H Fig. 2.3 [2] [Total: 10]

10 marks

Mark scheme: 2(a) magnesium carbonate AND hydrochloric acid ; 2 magnesium chloride ; 2(b)(i) 38–40 (s) ; 1 2(b)(ii) C ; 2 lowest rate of reaction / curve is less steep / reaction takes longer to complete ; 2(b)(iii) any two from: 2 change temperature ; use catalyst ; change, size / surface area (of particles / magnesium carbonate) ; 2(c)(i) covalent ; 1 2(c)(ii) bonding pair between each hydrogen and the oxygen ; 2 2 lone pairs / 4 non-bonding electrons on oxygen outer shell AND all else correct ;

This question in 0653/31 Oct/Nov 2024

4 (a) Iron is a metal. Fig. 4.1 shows the three physical states of iron. A solid liquid gas B Fig. 4.1 Name the changes of state shown by arrows A and B. A … B … [2] (b) Complete the sentences about the particles in a liquid. Use words or phrases from the list. Each word or phrase may be used once, more than once or not at all. at the same speed as more quickly than stable more slowly than regular random The particles in a liquid move … in a solid. Particles in a liquid have a … arrangement. [2] (c) The symbol equation for the reaction of solid iron with oxygen is shown. 4Fe( … ) + 3O2( … ) 2Fe2O3(s) (i) Complete the symbol equation by adding the state symbols. [1] (ii) Explain how the equation shows that oxidation takes place. … … [1] (d) Iron is used as a catalyst in a reaction to make ammonia. Describe the effect of a catalyst on the rate of reaction. … [1] [Total: 7]

7 marks

Mark scheme: 4(a) A: melting / melt ; 2 B: condensing / condensation ; 4(b) more quickly than ; 2 random ; 4(c)(i) s and g ; 1 4(c)(ii) Fe / iron, gains oxygen ; 1 4(d) increases (the rate) ; 1

This question in 0653/31 May/June 2025

6 Hydrogen peroxide, H2O2, decomposes into water and oxygen when a catalyst is added. (a) Balance the symbol equation for the reaction. … H2O2 … H2O + O2 [1] (b) The oxygen is collected and tested. Describe the test for oxygen gas. State the observation for the positive result. test … observation … [1] (c) Anhydrous cobalt(II) chloride is used to test for water. State the colour observed for a positive result. … [1] (d) Describe what is meant by a catalyst. … … … … [2] (e) The temperature of the hydrogen peroxide is increased. All other conditions stay the same. Predict the effect of this change on the reaction. … [1] [Total: 6]

6 marks

Mark scheme: 6(a) 2 and 2 ; 1 6(b) glowing splint and relights ; 1 6(c) pink ; 1 6(d) (a substance that) increases rate of reaction ; 2 is unchanged at end of a reaction ; 6(e) increases the rate (of reaction) ; 1

This question in 0653/32 May/June 2025