0653.C4.1.01 — Define electrolysis as the decomposition of an ionic compound, when molten or in aqueous solution, by the passage of an electric current: past paper questions
Real questions on 0653.c4.1.01 — define electrolysis as the decomposition of an ionic compound, when molten or in aqueous solution, by the passage of an electric current
The newest 20 of 21 written questions. Open one to see it on the real paper.
- 0653/42 · May/June 2025 · Q4c(i)[2]
Define electrolysis.
See it on the paper → - 0653/32 · February/March 2025 · Q6b[1]
Explain why the mass of concentrated aqueous sodium chloride decreases during electrolysis.
See it on the paper → - 0653/32 · February/March 2025 · Q6c[1]
Use Table 6.1 to explain why electrolysis is a chemical change.
See it on the paper → - 0653/21 · October/November 2024 · Q18[1]
Which row describes what happens at the anode and at the cathode?
See it on the paper → - 0653/32 · October/November 2024 · Q8c[1]
Dilute sulfuric acid is the electrolyte in this electrolysis. Complete the sentence about electrolytes.
See it on the paper → - 0653/33 · October/November 2024 · Q8c[1]
Dilute sulfuric acid is the electrolyte in this electrolysis. Complete the sentence about electrolytes.
See it on the paper → - 0653/43 · October/November 2024 · Q5a[2]
Electrolysis is the breakdown of an ionic when molten or in (a) Use one word in each gap to complete the definition of electrolysis.
See it on the paper → - 0653/43 · October/November 2024 · Q5b[2]
Hydrogen gas forms at the negative electrode. Complete the ionic equation for the reaction. +
See it on the paper → - 0653/43 · October/November 2024 · Q5c[2]
Dilute sulfuric acid contains water. Hydroxide ions from the water react at the positive electrode to form oxygen gas. Describe what happens to the hydroxide ions in this reaction.
See it on the paper → - 0653/43 · October/November 2024 · Q5d[1]
Universal indicator is added to the dilute sulfuric acid at the beginning of the electrolysis. The universal indicator turns red. Explain why the universal indicator does not change colour when the dilute sulfuric acid is electrolysed.
See it on the paper → - 0653/42 · February/March 2024 · Q5a(i)[1]
Explain why the zinc chloride must be molten in this electrolysis.
See it on the paper → - 0653/31 · October/November 2023 · Q8b(i)[1]
State the name of the process that breaks down compounds by passing an electric current through them.
See it on the paper → - 0653/33 · May/June 2023 · Q5e[1]
Aqueous magnesium sulfate is broken down by an electric current. State the name of this process.
See it on the paper → - 0653/43 · May/June 2023 · Q2a(i)[3]
Describe in words the reaction at the positive electrode.
See it on the paper → - 0653/43 · May/June 2023 · Q2a(ii)[2]
Complete the ionic equation for the reaction at the negative electrode. 2H + (aq) + (g)
See it on the paper → - 0653/43 · May/June 2023 · Q2b[2]
Dilute sulfuric acid is the electrolyte in this electrolysis. State the meaning of electrolyte.
See it on the paper → - 0653/43 · May/June 2023 · Q2c[1]
A different aqueous solution is electrolysed. The products of this electrolysis are hydrogen and chlorine. Suggest the identity of this aqueous solution.
See it on the paper → - 0653/42 · February/March 2023 · Q2b[2]
The lamp only lights up when the temperature of the lead( II ) chloride is greater than 501 °C. Explain why. Use ideas about ions in your answer.
See it on the paper → - 0653/42 · February/March 2023 · Q2c(i)[2]
Complete the symbol equation for the electrolysis reaction. Include the state symbols. PbC l ( ) ( ) + ( )
See it on the paper → - 0653/11 · October/November 2022 · Q16[1]
What are the products of the electrolysis of dilute sulfuric acid using inert electrodes?
See it on the paper →
What examiners said
Only some candidates gained full credit on this question about electrolysis. Candidates are referred to the definition of electrolysis given in the syllabus. Candidates should refer to electric current rather than electricity when describing how the ions are separated.
— Examiner report, May/June 2025, 0653/42 Q4(c)(i) (Cambridge)
Candidates found this question challenging. Since the products of the electrolysis of concentrated aqueous sodium chloride are both gases, the bubbles of gas are released, and the mass of the electrolyte reduces. Most candidates did not make this observation. Common errors included statements that the electrolyte gets hot, or that it evaporates.
— Examiner report, February/March 2025, 0653/32 Q6(b) (Cambridge)
This question was generally answered well. Many candidates understood that new substances are formed during electrolysis, therefore the process must be a chemical change.
— Examiner report, February/March 2025, 0653/32 Q6(c) (Cambridge)
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