Electrolysis: Edexcel GCSE Chemistry questions

Every Edexcel GCSE Chemistry exam question on Electrolysis (specification points 3.22–3.31), 2018–2025, with its mark scheme and examiner’s report.

All 79 questions on Electrolysis, as a list

June 2025, Paper 1 Higher, Q8(c) (6 marks): Magnesium sulfate solution can be electrolysed using the apparatus shown in Figure 7. oxygen hydrogen magnesium sulfate solution positive negative + – electrod
June 2024, Paper 1 Higher, Q7(a)(i) (2 marks): In this electrolysis, the acidified water is an electrolyte. Explain why acidified water is an electrolyte. (2)
June 2024, Paper 1 Higher, Q7(a)(ii) (1 mark): Hydrogen collects at the negative electrode and oxygen collects at the positive electrode. Which of these shows the results after 10 minutes of this electrolysi
June 2024, Paper 1 Higher, Q7(a)(iii) (2 marks): Complete and balance the half equation for the formation of oxygen at the positive electrode in this electrolysis. (2) 4OH– →
June 2024, Paper 1 Higher, Q7(b)(i) (2 marks): Describe what should be done to the copper cathode, after it has been removed from the copper sulfate solution, before its final mass is determined. (2)
June 2024, Paper 1 Higher, Q7(b)(ii) (2 marks): Explain, in terms of ions, the change in mass of the cathode shown in Figure 6. (2)
June 2024, Paper 1 Higher, Q7(b)(iii) (2 marks): Explain why the appearance of the copper sulfate solution did not change during the electrolysis. (2)
June 2024, Paper 1 Foundation, Q6(c)(i) (2 marks): Give two reasons why graphite is a suitable material for the electrodes. (2) 1 2
June 2024, Paper 1 Foundation, Q6(c)(ii) (1 mark): Sodium sulfate solution contains ions. Which ions are attracted to the positive electrode during the electrolysis? (1) A H+ ions only B OH– ions only C H+ and N
June 2024, Paper 1 Foundation, Q6(c)(iii) (2 marks): Draw one straight line from each electrode to the product formed at that electrode during the electrolysis of sodium sulfate solution. (2) electrode product hyd
June 2023, Paper 1 Higher, Q6(a) (1 mark): Where is copper formed during the electrolysis? (1) A at the anode B at the bottom of the beaker C at the cathode D on the surface of the electrolyte
June 2023, Paper 1 Higher, Q6(b)(i) (3 marks): State and explain the trend shown in these results. (3)
June 2023, Paper 1 Higher, Q6(b)(ii) (2 marks): Describe how, after the power supply has been switched off, the mass of copper formed can be measured. (2)
June 2023, Paper 1 Foundation, Q3(a) (1 mark): Which statement describes what happens during electrolysis? (1) A atoms are decomposed B ionic compounds are decomposed C mixtures are separated D molecules are
June 2023, Paper 1 Foundation, Q3(b)(i) (2 marks): Use the words from the box to complete the labelling of the diagram in Figure 5. (2) anode cathode electrolyte 6 V d.c. supply – + solid X gas Y Figure 5
June 2023, Paper 1 Foundation, Q3(b)(ii) (2 marks): The products of the electrolysis shown in Figure 5 are solid X and gas Y. Draw one straight line from each product to its name. (2) product name carbon solid X
June 2023, Paper 1 Foundation, Q3(b)(iii) (2 marks): The experiment is repeated using powdered solid copper chloride instead of copper chloride solution. Nothing happens and no products are formed. Explain why not
June 2023, Paper 2 Foundation, Q6(b)(vi) (1 mark): Sodium chloride solution conducts electricity. 6V d.c. circuit supply electrode electrode sodium chloride solution Figure 11 State what can be put into the circ
June 2022, Paper 1 Higher, Q5(a) (2 marks): Draw a labelled diagram to show the apparatus that can be used to electrolyse copper sulfate solution using copper electrodes. (2)
June 2022, Paper 1 Higher, Q5(b) (2 marks): Before the electrolysis is carried out, the mass of each electrode is determined. Explain what should be done to the copper electrodes before their masses are d
June 2022, Paper 1 Higher, Q5(c)(i) (3 marks): Explain, in terms of ions, the changes in mass of the two electrodes shown in the results in Figure 4. (3)
June 2022, Paper 1 Higher, Q5(c)(ii) (2 marks): The electrolysis was repeated using another pair of copper electrodes of the same masses. Explain a change that could be made to the electrolysis experiment to
June 2022, Paper 1 Foundation, Q6(c)(i) (1 mark): Figure 11 shows the ions in the sodium sulfate solution. Draw a circle around each of the ions in Figure 11 that are attracted to the negative graphite electrod
June 2022, Paper 1 Foundation, Q6(c)(ii) (1 mark): State why it is important that the electrodes are inert. (1)
June 2022, Paper 1 Foundation, Q7(c) (6 marks): Pure metals can be made more useful by converting them into alloys or by electroplating them. Explain what alloying and electroplating are and how they can make
November 2021, Paper 1 Higher, Q4(d) (2 marks): Metal objects can be electroplated with gold. Give two reasons why metal objects are electroplated with gold. (2) 1 2
November 2021, Paper 1 Higher, Q5(a) (1 mark): A sample of molten potassium bromide is electrolysed. What are the two products formed? (1) A hydrogen and oxygen B hydrogen and bromine C potassium and oxygen
November 2021, Paper 1 Higher, Q5(b) (2 marks): Zinc chloride and zinc carbonate contain ions. Zinc chloride mixed with water can be electrolysed. Zinc carbonate mixed with water cannot be electrolysed. Expla
November 2021, Paper 1 Higher, Q5(c)(i) (1 mark): Identify this gas. (1)
November 2021, Paper 1 Higher, Q5(c)(ii) (2 marks): Explain how this gas is formed at the cathode. (2)
November 2021, Paper 1 Higher, Q5(d)(i) (2 marks): Draw a labelled diagram to show how this experiment would be set up. The beaker has been drawn for you. (2) beaker
November 2021, Paper 1 Higher, Q5(d)(ii) (3 marks): During the electrolysis, the anode gets smaller, the cathode gets larger and the solution remains the same shade of blue. Give the reason for each of these obse
November 2021, Paper 1 Foundation, Q6(b)(i) (1 mark): Give the name of the piece of apparatus labelled X. (1)
November 2021, Paper 1 Foundation, Q6(b)(ii) (1 mark): The rod labelled Y in Figure 6 is made of graphite. What is the name of this piece of apparatus? (1) A electrode B electrolysis C electrolyte D electron
November 2021, Paper 1 Foundation, Q6(b)(iii) (1 mark): Give one reason why graphite is a suitable material to make Y. (1)
November 2021, Paper 1 Foundation, Q6(b)(iv) (1 mark): Complete the balanced equation for the reaction that occurs. (1) HCl → H2 + Cl2
November 2021, Paper 1 Foundation, Q10(d) (2 marks): Metal objects can be electroplated with gold. Give two reasons why metal objects are electroplated with gold. (2) 1 2
November 2020, Paper 1 Higher, Q2(a)(i) (2 marks): Describe the test to show the gas is hydrogen. (2)
November 2020, Paper 1 Higher, Q2(a)(ii) (1 mark): What is the name of gas X that forms at the positive electrode? (1) A ammonia B oxygen C nitrogen D sulfur dioxide
November 2020, Paper 1 Higher, Q2(a)(iii) (2 marks): State what is meant by the term electrolysis. (2)
November 2020, Paper 1 Foundation, Q7(b) (1 mark): Give one reason why metals are electroplated. (1)
November 2020, Paper 1 Foundation, Q8(a)(i) (2 marks): Describe the test to show the gas is hydrogen. (2)
November 2020, Paper 1 Foundation, Q8(a)(ii) (1 mark): What is the name of gas X that forms at the positive electrode? (1) A ammonia B oxygen C nitrogen D sulfur dioxide
November 2020, Paper 1 Foundation, Q8(a)(iii) (2 marks): State what is meant by the term electrolysis. (2)
November 2020, Paper 1 Foundation, Q8(d)(i) (1 mark): In Figure 11, the gases given off at the electrodes are collected in test-tubes. However, the actual volume of gases cannot be measured using these test-tubes.
November 2020, Paper 1 Foundation, Q8(d)(ii) (1 mark): State what could be added into the circuit to show a current is flowing during electrolysis. (1)
June 2019, Paper 1 Higher, Q1(c) (2 marks): Some metal objects are electroplated. State two reasons for electroplating a metal object. (2) 1 2
June 2019, Paper 1 Higher, Q3(a)(i) (1 mark): A sample of hydrogen is mixed with air and ignited. State what would happen. (1)
June 2019, Paper 1 Higher, Q3(a)(ii) (2 marks): Throughout the experiment the volume of hydrogen and the volume of oxygen are measured at two-minute intervals. The results are shown in Figure 2. volume of hyd
June 2019, Paper 1 Higher, Q3(b) (1 mark): Molten lead bromide is electrolysed. The products of this electrolysis are (1) A hydrogen and bromine B hydrogen and oxygen C lead and bromine D lead and oxygen
June 2019, Paper 1 Higher, Q3(c) (2 marks): Calcium nitrate and calcium carbonate are both ionic compounds. Calcium nitrate mixed with water behaves as an electrolyte. Calcium carbonate mixed with water d
June 2019, Paper 1 Higher, Q3(d) (2 marks): When molten zinc chloride is electrolysed, zinc ions, Zn2+, form zinc atoms. Write the half equation for this reaction. (2)
June 2019, Paper 1 Foundation, Q6(c)(ii) (2 marks): Complete the balanced equation for the overall reaction by putting numbers in the spaces. (2) 2AL,O3 → Al +
June 2019, Paper 1 Foundation, Q9(a)(ii) (2 marks): Throughout the experiment the volume of hydrogen and the volume of oxygen are measured at two-minute intervals. The results are shown in Figure 9. volume of hyd
June 2019, Paper 1 Foundation, Q9(b) (1 mark): Molten lead bromide is electrolysed. The products of this electrolysis are (1) A hydrogen and bromine B hydrogen and oxygen X C lead and bromine D lead and oxyg
June 2019, Paper 1 Foundation, Q9(c) (2 marks): Calcium nitrate and calcium carbonate are both ionic compounds. Calcium nitrate mixed with water behaves as an electrolyte. Calcium carbonate mixed with water d
June 2019, Paper 1 Foundation, Q9(d) (6 marks): Impure copper can be purified using electrolysis. In this electrolysis • the anode is made of impure copper • the cathode is made from pure copper • the electro
June 2018, Paper 1 Higher, Q6(a)(i) (1 mark): Which row shows the products formed at the anode and at the cathode when molten zinc chloride is electrolysed? (1) product at anode product at cathode A oxygen
June 2018, Paper 1 Higher, Q6(a)(ii) (1 mark): Which of the following is the reason why molten zinc chloride is an electrolyte? (1) A it contains molecules that can move B it has a giant structure C it conta
June 2018, Paper 1 Higher, Q6(b)(i) (2 marks): Draw a labelled diagram to show the apparatus that is used to carry out this electrolysis in the laboratory. (2)
June 2018, Paper 1 Higher, Q6(b)(ii) (4 marks): Before the electrolysis, the masses of the electrodes were determined. After the electrolysis, the electrodes were washed and dried and their masses re-determin
June 2018, Paper 1 Higher, Q6(c) (2 marks): When sodium sulfate solution is electrolysed, using inert electrodes, hydrogen is formed at the cathode. +. Write the half equation for the formation of hydroge
June 2018, Paper 1 Foundation, Q5(e)(i) (1 mark): State why sodium chloride solution, rather than solid sodium chloride, must be used in this experiment. (1)
June 2018, Paper 1 Foundation, Q5(e)(ii) (1 mark): The formulae of the ions present in the sodium chloride solution are Na+ Cl– H+ OH– Circle the ions that would be attracted to the anode. (1)
June 2018, Paper 1 Foundation, Q5(e)(iii) (2 marks): Molten lead bromide can be electrolysed to form molten lead and bromine gas. Explain how a student could modify the apparatus shown in Figure 8 to carry out thi
June 2018, Paper 1 Foundation, Q7(c)(i) (1 mark): State to what the anode and cathode have to be connected in order to carry out the electroplating. (1)
June 2018, Paper 1 Foundation, Q7(c)(ii) (1 mark): Predict the name of a substance that could be dissolved in water to form the electrolyte for this electroplating. (1)
Specimen, Paper 1 Higher, Q5(a)(i) (1 mark): Which row of the table correctly shows the charge on the silver rod electrode and the type of reaction occurring at this electrode? (1) charge type of reaction
Specimen, Paper 1 Higher, Q5(a)(ii) (1 mark): Silver metal is deposited on the spoon. Which half-equation represents this reaction? (1) A Ag + e → Ag+ B Ag → Ag+ + e− C Ag+ + e → Ag D Ag+ → Ag + e−
Specimen, Paper 1 Higher, Q6(a) (2 marks): Explain which solutions are electrolytes. (2)
Specimen, Paper 1 Higher, Q6(b) (1 mark): Which material is most suitable to make the electrodes for the electrolysis of a dilute acid? (1) A zinc B sulfur C iron D graphite
Specimen, Paper 1 Higher, Q6(c) (4 marks): When a solution of sodium sulfate, Na2SO4, is electrolysed, the products formed at the electrodes are hydrogen and oxygen. Explain the formation of the products
Specimen, Paper 1 Higher, Q6(d) (2 marks): Copper is purified by the electrolysis of copper sulfate solution using an impure copper anode and a pure copper cathode. Write the half-equation for the format
Specimen, Paper 1 Foundation, Q4(a)(i) (1 mark): State an improvement that can be made to the circuit to show that a current is flowing during the electrolysis. (1) Some of these solutions are electrolytes.
Specimen, Paper 1 Foundation, Q4(a)(ii) (2 marks): State what is meant by the term electrolyte. (2)
Specimen, Paper 1 Foundation, Q4(a)(iii) (1 mark): Which of J, K and L are electrolytes? (1) A K only B J and L only C K and L only D J, K and L
Specimen, Paper 1 Foundation, Q4(b) (2 marks): Copper sulfate solution was electrolysed for five minutes using copper electrodes. Figure 5 shows the mass of the anode and of the cathode before electrolysis a
Specimen, Paper 1 Foundation, Q4(c) (2 marks): Identify the products formed at the anode and cathode when molten potassium iodide is electrolysed. (2) Anode Cathode
Specimen, Paper 1 Foundation, Q5(a) (2 marks): Give two advantages for electroplating some metal objects. (2)

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