Types of chemical reactions: OCR GCSE Combined Science A questions

Every OCR GCSE Combined Science A exam question on C3.3 Types of chemical reactions, 2018–2025, with its mark scheme and examiner’s report.

All 109 questions on Types of chemical reactions, as a list

June 2025, Chemistry Paper 3 Foundation, Q5 (1 mark): Methane reacts with oxygen to make carbon dioxide and water. CH4 + 2O2 CO2 + 2H2O Which chemical is being oxidised? A CH4 B CO2 C H2O D O2 Your answer [1]
June 2025, Chemistry Paper 3 Foundation, Q7 (1 mark): Which particle in dilute hydrochloric acid, HCl, makes it acidic? Cl – A H+ B C H2O OH– D Your answer [1]
June 2025, Chemistry Paper 3 Foundation, Q15(a)(i) (1 mark): Suggest the pH of dilute sulfuric acid. [1]
June 2025, Chemistry Paper 3 Foundation, Q15(a)(ii) (2 marks): Name an indicator that the student could use to measure the pH of dilute sulfuric acid. State the colour of the indicator after it has been added to the dilute
June 2025, Chemistry Paper 3 Foundation, Q15(a)(iii) (1 mark): Name a piece of equipment the student could use to measure the pH more accurately. [1]
June 2025, Chemistry Paper 3 Foundation, Q15(b) (1 mark): When magnesium carbonate reacts with dilute sulfuric acid, it forms a salt, water and carbon dioxide. What is the name of the salt? [1]
June 2025, Chemistry Paper 3 Foundation, Q15(c) (2 marks): The student adds an excess of magnesium carbonate to dilute sulfuric acid until no more of it reacts. magnesium carbonate(s) + sulfuric acid(aq) salt(aq) + wate
June 2025, Chemistry Paper 3 Foundation, Q15(e)(i) (2 marks): Describe the relationship between the mass of magnesium carbonate and the mass of the salt. [2]
June 2025, Chemistry Paper 3 Foundation, Q15(e)(ii) (1 mark): A student thinks that when 6.0 g of magnesium carbonate has been added it is in excess. Explain why the student is correct. [1]
June 2025, Chemistry Paper 9 Higher, Q8 (1 mark): The reaction of iron, Fe, with copper ions, Cu2+, can be written as two half equations. 8 Fe2+ + 2e– Fe Cu2+ + 2e– Cu Which species is oxidised? A Cu B Fe Cu2+
June 2025, Chemistry Paper 9 Higher, Q11(a)(i) (1 mark): Suggest the pH of dilute sulfuric acid. [1]
June 2025, Chemistry Paper 9 Higher, Q11(a)(ii) (2 marks): Name an indicator that the student could use to measure the pH of dilute sulfuric acid. State the colour of the indicator after it has been added to the dilute
June 2025, Chemistry Paper 9 Higher, Q11(a)(iii) (1 mark): Name a piece of equipment the student could use to measure the pH more accurately. [1]
June 2025, Chemistry Paper 9 Higher, Q11(b) (1 mark): When magnesium carbonate reacts with dilute sulfuric acid, it forms a salt, water and carbon dioxide. What is the name of the salt? [1]
June 2025, Chemistry Paper 9 Higher, Q11(c) (2 marks): The student adds an excess of magnesium carbonate to dilute sulfuric acid until no more of it reacts. magnesium carbonate(s) + sulfuric acid(aq) salt(aq) + wate
June 2025, Chemistry Paper 9 Higher, Q11(d) (2 marks): The student separates the salt from the solution formed at the end of the reaction. Step 1: They remove the excess magnesium carbonate. Step 2: They remove the
June 2025, Chemistry Paper 9 Higher, Q11(e)(i) (2 marks): Describe the relationship between the mass of magnesium carbonate and the mass of the salt. [2]
June 2025, Chemistry Paper 9 Higher, Q11(e)(ii) (1 mark): A student thinks that when 6.0 g of magnesium carbonate has been added it is in excess. Explain why the student is correct. [1]
June 2025, Chemistry Paper 9 Higher, Q15(a) (1 mark): Why are solutions of sodium hydroxide and calcium hydroxide called alkalis? [1]
June 2024, Chemistry Paper 3 Foundation, Q2 (1 mark): Magnesium reacts with oxygen to make magnesium oxide. magnesium + oxygen magnesium oxide Which type of reaction is shown by the equation? A Displacement B Elect
June 2024, Chemistry Paper 3 Foundation, Q5 (1 mark): The table shows the colours of an indicator at different pH values. 1 2 3 4 5 6 7 8 9 10 11 12 Pink Orange Purple Green Which colour is this indicator in a neut
June 2024, Chemistry Paper 3 Foundation, Q8 (1 mark): What is the ionic equation for an aqueous neutralisation reaction? H+ + OH+ A H2O H+ + OH– B H2O H– + OH+ C H2O H– + OH– D H2O Your answer [1]
June 2024, Chemistry Paper 4 Foundation, Q9 (1 mark): Carbon reacts with copper oxide to produce copper. copper oxide + carbon copper + carbon dioxide What is the role of the carbon? A It is a catalyst. B It neutra
June 2024, Chemistry Paper 4 Foundation, Q16(e)(i) (1 mark): This is the equation for the electrolysis of aluminium oxide. 2Al 2O3 4Al + 6O2 A student thinks that this reaction is an example of reduction. Explain why the
June 2024, Chemistry Paper 9 Higher, Q14(a) (2 marks): Write the formula of the molecules in the box for R to show a balanced reaction. [2]
June 2024, Chemistry Paper 9 Higher, Q14(b) (2 marks): Write the name and the formula of the compound in solution S. Name Formula [2]
June 2024, Chemistry Paper 9 Higher, Q14(c) (1 mark): Name the type of reaction which happens between solutions P and Q. [1]
June 2024, Chemistry Paper 9 Higher, Q14(d) (3 marks): Which of the solutions in the diagram shows a strong acid? Tick (3) one box. P Q S Give two reasons for your answer. 1 2 [3]
June 2024, Chemistry Paper 10 Higher, Q1 (1 mark): Carbon reacts with copper oxide to produce copper. copper oxide + carbon copper + carbon dioxide What is the role of the carbon? A It is a catalyst. B It neutra
June 2024, Chemistry Paper 10 Higher, Q9 (1 mark): Fluorine gas reacts with sodium to form sodium fluoride. What is the balanced half equation for the reaction of fluorine when it reacts with sodium? F + e– F –
June 2024, Chemistry Paper 10 Higher, Q11(e)(i) (1 mark): This is the equation for the electrolysis of aluminium oxide. 2Al 2O3 4Al + 6O2 A student thinks that this reaction is an example of reduction. Explain why the
June 2023, Chemistry Paper 3 Foundation, Q3 (1 mark): Which is an example of a neutralisation reaction? A A metal reacting with an acid B A non-metal reacting with oxygen C A salt dissolving in water D An acid reac
June 2023, Chemistry Paper 3 Foundation, Q14(b) (1 mark): Name the salt, ZnSO4, made from zinc and sulfuric acid. [1]
June 2023, Chemistry Paper 3 Foundation, Q14(c) (2 marks): To make sure all the sulfuric acid reacts, an excess of zinc is used. Describe how universal indicator could be used to show that all the sulfuric acid has reac
June 2023, Chemistry Paper 9 Higher, Q4 (1 mark): Copper carbonate reacts with dilute hydrochloric acid to form copper chloride, water and a gas. What is the formula of the gas? A C B CO C CO2 D CO3 Your answer
June 2023, Chemistry Paper 9 Higher, Q15(a) (1 mark): Describe the difference between a strong acid and a weak acid. [1]
June 2023, Chemistry Paper 9 Higher, Q15(b)(i) (1 mark): Write the formula of the ion that gives the dilute hydrochloric acid solution the pH shown on the graph. [1]
June 2023, Chemistry Paper 9 Higher, Q15(b)(ii) (2 marks): The pH of the dilute hydrochloric acid solution can be measured using either universal indicator or a pH meter. Explain which method would be better to use for
June 2023, Chemistry Paper 9 Higher, Q15(c) (2 marks): Describe how the pH changes with the concentration of dilute hydrochloric acid solution on the graph. [2]
June 2023, Chemistry Paper 9 Higher, Q15(d) (2 marks): As the concentration of the dilute hydrochloric acid solution increases by a factor of ten, the pH of the solution decreases by one. Use data from the graph to
June 2023, Chemistry Paper 9 Higher, Q15(e) (4 marks): Calculate the mass of hydrochloric acid, HCl , in 100 cm3 of solution that gives a pH 1.5. Use data from the graph. Give your answer to 2 significant figures. R
June 2023, Chemistry Paper 10 Higher, Q15(a) (1 mark): In Stage 1 iodide ions are produced by reduction. Explain reduction in terms of electrons. [1]
June 2023, Chemistry Paper 10 Higher, Q15(b) (2 marks): In Stage 2 iodide ions are oxidised to iodine. Complete the half-equation for the oxidation of iodide ions into iodine. 2I – → [2]
June 2022, Chemistry Paper 3 Foundation, Q4 (1 mark): Which particles in an aqueous solution of sodium hydroxide, NaOH(aq), make it alkaline? H+ A B H2O OH– C Na+ D Your answer [1]
June 2022, Chemistry Paper 3 Foundation, Q5 (1 mark): The table shows the colours of universal indicator in solutions of different pH. pH 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Colour red orange yellow green blue purple
June 2022, Chemistry Paper 3 Foundation, Q10 (1 mark): The equation shows the reaction between carbon dioxide, CO2, and hydrogen, H2. CO2 + H2 CO + H2O What is the oxidising agent in the reaction? A CO B CO2 C H2 D
June 2022, Chemistry Paper 3 Foundation, Q14 (6 marks): 14* A student wants to produce a pure dry sample of the salt sodium chloride. The diagram shows the method they use. 2 cm3 portions of Solution formed sodium hy
June 2022, Chemistry Paper 9 Higher, Q2 (1 mark): The equation shows the reaction between carbon dioxide, CO2, and hydrogen, H2. CO2 + H2 CO + H2O What has been reduced in this reaction? A CO B CO2 C H2 D H2O Y
June 2022, Chemistry Paper 9 Higher, Q6 (1 mark): The table shows some information about four different acids. Number of particles per Degree of ionisation Acid cm3 of acid solution (%) A high 1 B low 1 C high
June 2022, Chemistry Paper 9 Higher, Q9 (1 mark): A solution has a pH of 3. The solution is diluted with water by a factor of 1000. What is the pH of the solution after dilution? A 2 B 4 C 5 D 6 Your answer [1]
June 2022, Chemistry Paper 9 Higher, Q14(e)(i) (1 mark): Write the balanced ionic equation for the reaction of dilute hydrochloric acid and a solution of calcium hydroxide. [1]
June 2022, Chemistry Paper 9 Higher, Q14(e)(ii) (3 marks): Describe and explain how the pH of the solution of calcium hydroxide changes as the dilute hydrochloric acid is added until it is in excess. [3]
June 2022, Chemistry Paper 9 Higher, Q15(a) (2 marks): A student thinks that the half equation shows that reduction has taken place. Describe two ways in which the half equation shows the student is correct. 1 2 [2]
June 2022, Chemistry Paper 9 Higher, Q15(b) (1 mark): This half equation shows the reaction of the zinc. + 2e– Zn Complete the half equation for the reaction. [1]
June 2022, Chemistry Paper 9 Higher, Q15(c) (1 mark): The student removes the zinc from the green solution by filtration. When they add some nitric acid to this solution it turns back from green to blue. What is th
November 2021, Chemistry Paper 3 Foundation, Q8 (1 mark): Iron oxide, Fe2O3, is heated with carbon, C. Iron, Fe, and another product, X, are made. Look at the equation for the reaction. Fe2O3(s) + 3C(s) 2Fe(s) + 3X(g)
November 2021, Chemistry Paper 3 Foundation, Q12(b) (1 mark): Which compound, A, B, C, D or E, is made when copper is oxidised as copper reacts with oxygen? [1]
November 2021, Chemistry Paper 3 Foundation, Q12(c) (1 mark): Which compound, A, B, C, D or E, reacts with dilute hydrochloric acid to make carbon dioxide? [1]
November 2021, Chemistry Paper 3 Foundation, Q13(a) (1 mark): What is the name of the piece of equipment labelled X? [1]
November 2021, Chemistry Paper 3 Foundation, Q13(b) (1 mark): Fig. 13.2 shows two pieces of equipment which could be used to measure 0.5 cm3 of the sodium hydroxide solution. 25 cm3 25 20 1.0 cm3 15 0.5 cm3 10 5 Dropping p
November 2021, Chemistry Paper 3 Foundation, Q13(c) (3 marks): The student plots a graph of some of their results. Look at the table. It shows the rest of the student’s results. Volume of sodium hydroxide solution (cm3) 8.0
November 2021, Chemistry Paper 3 Foundation, Q13(d) (1 mark): The dilute hydrochloric acid is exactly neutralised when the pH of the mixture is 7. Use the graph to work out the volume of sodium hydroxide solution needed to
November 2021, Chemistry Paper 3 Foundation, Q13(e) (2 marks): The dilute hydrochloric acid is neutralised by the sodium hydroxide solution. Complete the sentence using the words shown. You may use each word once, more than
November 2021, Chemistry Paper 9 Higher, Q6 (1 mark): Which equation shows the ionisation of a weak acid? H+(aq) + Cl –(aq) A HCl (aq) HCOO–(aq) + H+(aq) B HCOOH(aq) Na+(aq) + OH–(aq) C NaOH(aq) +(aq) + OH–(aq) D N
November 2021, Chemistry Paper 9 Higher, Q8 (1 mark): Look at the ionic equation. Mg(s) + Cu2+(aq) Mg2+(aq) + Cu(s) Which species is reduced? A Cu(s) Cu2+(aq) B C Mg(s) Mg2+(aq) D Your answer [1]
November 2021, Chemistry Paper 9 Higher, Q9 (1 mark): A solution has a hydrogen ion concentration of 1 × 10–6 mol / dm3. The solution has a pH of 6. 9 What is the hydrogen ion concentration of a solution with a pH
November 2020, Chemistry Paper 3 Foundation, Q4: Which particle in a solution of dilute hydrochloric acid, HCI, makes it acidic? 4 A CI B Ht C H2O D OH [11 Your answer
November 2020, Chemistry Paper 3 Foundation, Q9 (1 mark): Iron can be made from the reaction of iron(III) oxide with carbon monoxide. Fe,0z + 3C0 → 2Fe+ 3C0½ What is the reducing agent in this reaction? A СО в СО2 C Fe
November 2020, Chemistry Paper 3 Foundation, Q12(f)(i) (1 mark): What is the name of the gas produced? [1]
November 2020, Chemistry Paper 4 Foundation, Q13(b) (1 mark): In the reaction copper ions in the copper oxide are reduced. Explain why. • [1]
November 2020, Chemistry Paper 9 Higher, Q1 (1 mark): Iron can be made from the reaction of iron(III) oxide with carbon monoxide. Fe2O3 + 3CO 2Fe + 3CO2 What is the reducing agent in this reaction? A CO B CO2 C Fe
November 2020, Chemistry Paper 9 Higher, Q8 (1 mark): Which curve shows how the pH of a strong alkali changes when a strong acid is added? A 14 12 10 8 pH 6 4 2 00 5 10 15 20 25 30 Volume of strong acid (cm3) B 14
November 2020, Chemistry Paper 9 Higher, Q14(a) (1 mark): Copper oxide is an insoluble compound that neutralises dilute hydrochloric acid. Name the type of insoluble compound that neutralises an acid to form a salt and
November 2020, Chemistry Paper 9 Higher, Q14(b) (1 mark): Dilute hydrochloric acid is a hazardous chemical. Describe one safety precaution the student should take when using dilute hydrochloric acid. [1]
November 2020, Chemistry Paper 9 Higher, Q14(c) (1 mark): Stage 1 uses an excess of copper oxide. Give a reason why. [1]
November 2020, Chemistry Paper 9 Higher, Q14(e)(i) (1 mark): Explain why this student is correct. [1]
November 2020, Chemistry Paper 9 Higher, Q14(e)(ii) (1 mark): Describe how the method in Fig. 14.1 can be improved to make pure copper chloride. [1]
November 2020, Chemistry Paper 9 Higher, Q16(a) (1 mark): Explain why phosphoric acid is described as a strong acid. [1]
November 2020, Chemistry Paper 9 Higher, Q16(b) (1 mark): Explain why the solution of phosphoric acid used is described as dilute. [1]
November 2020, Chemistry Paper 9 Higher, Q16(d) (2 marks): Look at Table 16.1. Describe how the pH of the solution formed changes as the concentration of the hydrogen ions in the solution changes by a factor of 10. Use
November 2020, Chemistry Paper 9 Higher, Q16(e) (2 marks): The reaction between phosphoric acid and calcium hydroxide is a neutralisation reaction. Write the balanced ionic equation for neutralisation. Include state sym
November 2020, Chemistry Paper 10 Higher, Q18(c)(i) (1 mark): Write the half equation for the formation of chloride ions, Cl−, from chlorine, Cl2. [1]
November 2020, Chemistry Paper 10 Higher, Q18(c)(ii) (1 mark): In this reaction is chlorine oxidised or reduced? Explain your answer. [1]
June 2019, Chemistry Paper 3 Foundation, Q13(a)(i) (1 mark): Which solution, A, B or C, is acidic? Tick (✓) one box. A B C [1]
June 2019, Chemistry Paper 3 Foundation, Q13(a)(ii) (1 mark): Suggest a pH value for the acidic solution. pH value = [1]
June 2019, Chemistry Paper 3 Foundation, Q13(a)(iii) (2 marks): Write down two other tests the student could use to identify that the solution is acidic. 1 2 [2]
June 2019, Chemistry Paper 3 Foundation, Q13(b) (1 mark): The student adds the acidic solution to a solution of sodium hydroxide. A neutralisation reaction takes place. He records the pH of the mixture. Table 13.2 show
June 2019, Chemistry Paper 3 Foundation, Q13(c) (1 mark): Sodium hydroxide is an alkali. Which ion do solutions of alkalis contain? Put a ring around the correct answer. H+ Na+ OH– SO4 2– [1]
June 2019, Chemistry Paper 3 Foundation, Q13(d) (1 mark): In a different neutralisation reaction sulfuric acid, H2SO4, reacts with sodium hydroxide, NaOH. Complete the balanced symbol equation for this reaction. H2SO4
June 2019, Chemistry Paper 3 Foundation, Q16(d)(i) (1 mark): During this reaction the aluminium is oxidised. Explain what is meant by the term oxidised. [1]
June 2019, Chemistry Paper 4 Foundation, Q13(c)(i) (1 mark): Which element in hexane is oxidised to produce water? Give a reason for your answer. element reason [1]
June 2019, Chemistry Paper 9 Higher, Q11(d)(i) (1 mark): During this reaction the aluminium is oxidised. Explain what is meant by the term oxidised. [1]
June 2019, Chemistry Paper 9 Higher, Q16(a) (1 mark): What volume of acid is needed to neutralise the alkali? Volume of acid = cm3 [1]
June 2019, Chemistry Paper 9 Higher, Q16(b) (2 marks): The mixture becomes less alkaline as the acid is added. Describe how the pH of the mixture changes as the acid is added. [2]
June 2019, Chemistry Paper 9 Higher, Q16(c) (2 marks): Explain why the mixture becomes less alkaline as the acid is added. Use ideas about hydrogen ions and pH in your answer. [2]
June 2019, Chemistry Paper 10 Higher, Q14(c)(ii) (1 mark): Give a reason for your answer to (c)(i). [1]
June 2018, Chemistry Paper 3 Foundation, Q2 (1 mark): A metal carbonate reacts with an acid. What products are made? A Salt and carbon dioxide B Salt and water C Salt, carbon dioxide and water D Salt, hydrogen and
June 2018, Chemistry Paper 3 Foundation, Q3 (1 mark): Ethanoic acid is a weak acid. What is the pH of ethanoic acid? A 1 B 5 C 7 D 12 Your answer [1]
June 2018, Chemistry Paper 3 Foundation, Q16(a) (1 mark): Write a word equation for this reaction. [1]
June 2018, Chemistry Paper 3 Foundation, Q16(b)(i) (1 mark): Calculate the mean temperature for experiment D. Answer = °C [1]
June 2018, Chemistry Paper 3 Foundation, Q16(b)(ii) (1 mark): Describe the pattern of the highest temperature reached for experiments A to C. [1]
June 2018, Chemistry Paper 3 Foundation, Q16(b)(iii) (1 mark): Describe the pattern of pH at the end of the reaction for experiments A to D. [1]
June 2018, Chemistry Paper 3 Foundation, Q16(b)(iv) (1 mark): How could the student measure the pH? [1]
June 2018, Chemistry Paper 3 Foundation, Q16(c) (1 mark): What conclusion can you draw from the student’s experiments? [1]
June 2018, Chemistry Paper 9 Higher, Q14(a) (1 mark): Complete the word equation for the reaction. Acid + Metal Carbonate → + + [1]
June 2018, Chemistry Paper 9 Higher, Q14(b) (1 mark): The student uses universal indicator in his experiment. Why did the student use universal indicator? [1]
June 2018, Chemistry Paper 9 Higher, Q14(c) (1 mark): An acid has a pH of 3. The hydrogen ion concentration of the acid is 1 × 10–3 mol / dm3. A different acid has a pH of 1. What is the hydrogen ion concentration
June 2018, Chemistry Paper 9 Higher, Q14(d)(i) (1 mark): What is the range of the results for Acid A? Answer = [1]
June 2018, Chemistry Paper 9 Higher, Q14(d)(ii) (2 marks): Evaluate the quality of the student’s results. [2]

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