10 free IGCSE Chemistry Electrochemistry questions written in the style of Cambridge Chemistry papers: 3 multiple-choice and 7 structured, each with its answer and mark scheme. 4 of them are A* challenge questions, built to catch the mistakes strong students still make.
This topic covers Electrolysis, Hydrogen–oxygen fuel cells. Work through the questions below, then generate a full Electrochemistry paper with a fresh set every time.
Generate a full Electrochemistry paper →Dilute sulfuric acid is electrolysed using inert electrodes.
What is formed at each electrode?
| cathode | anode | |
|---|---|---|
| A | oxygen | hydrogen |
| B | sulfur | oxygen |
| C | hydrogen | oxygen |
| D | hydrogen | sulfur dioxide |
Answer: C
What are the products at the electrodes when molten sodium chloride is electrolysed?
| cathode | anode | |
|---|---|---|
| A | sodium | chlorine |
| B | chlorine | sodium |
| C | sodium | bromine |
| D | copper | chlorine |
Answer: A
What is the only product of a hydrogen–oxygen fuel cell?
Answer: B
Dilute sulfuric acid is electrolysed using inert electrodes.
Name the products at each electrode.
State the ratio of the volumes of gases produced.
Write the half-equation at the anode.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | hydrogen at cathode; oxygen at anode cathode: hydrogen B1 anode: oxygen B1 | 2 |
| (b) | 2 : 1 hydrogen : oxygen hydrogen : oxygen = 2 : 1 B1 | 1 |
| (c) | 4OH⁻ → O₂ + 2H₂O + 4e⁻ 4OH⁻ → O₂ + 2H₂O + 4e⁻ (or 2H₂O → O₂ + 4H⁺ + 4e⁻) B2 | 2 |
Copper can be purified by electrolysis using copper(II) sulfate solution.
State which electrode is made of impure copper.
Describe and explain the changes in mass of each electrode.
Write the half-equation at the cathode.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | anode the anode B1 | 1 |
| (b) | anode loses mass, cathode gains anode loses mass as copper atoms form Cu²⁺ ions B1 cathode gains mass as Cu²⁺ ions are deposited as copper B1 | 2 |
| (c) | Cu²⁺ + 2e⁻ → Cu Cu²⁺ + 2e⁻ → Cu B1 | 1 |
A fuel cell uses hydrogen and oxygen to produce electricity.
State the energy change in a fuel cell.
Hydrogen is often made from methane. Explain why this reduces the environmental benefit of fuel cells.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | chemical → electrical chemical energy to electrical energy B1 | 1 |
| (b) | produces CO₂ from fossil fuel methane is a fossil fuel B1 making hydrogen from it releases carbon dioxide B1 | 2 |
A hydrogen–oxygen fuel cell is used to power a car.
Write the overall equation for the reaction in the fuel cell.
Give two advantages of fuel cells compared with petrol engines.
Give one disadvantage of hydrogen fuel cells.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 2H₂ + O₂ → 2H₂O correct formulae B1 balanced B1 | 2 |
| (b) | only water produced; more efficient only product is water (no CO₂/pollutants) B1 more efficient B1 | 2 |
| (c) | hydrogen storage/production Any 1 of: hydrogen is difficult to store (explosive/needs high pressure); hydrogen is often produced from fossil fuels B1 | 1 |
Compare fuel cells with petrol engines.
Give two disadvantages of fuel cell cars.
| Part | Answer and marking points | Marks |
|---|---|---|
| storage; few filling stations; cost Any 2 of: hydrogen is hard to store (high pressure/explosive); few hydrogen filling stations; expensive B2 | 2 |
Fig. 9.1 shows the apparatus for the electrolysis of concentrated aqueous sodium chloride using inert electrodes.
Name the products formed at the anode, at the cathode, and left in solution.
Describe a test for the gas produced at the anode and give the result.
The solution contains Na⁺, H⁺, Cl⁻ and OH⁻ ions.
Write the ionic half-equation for the formation of hydrogen at the cathode.
Explain why hydrogen, not sodium, is produced at the cathode.
Explain why the solution becomes alkaline during the electrolysis.
The electrolysis is repeated using dilute aqueous sodium chloride. Name the gas now produced at the anode and explain why it is different from the gas produced from concentrated solution.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | anode chlorine; cathode hydrogen; solution sodium hydroxide anode: chlorine B1 cathode: hydrogen B1 solution: sodium hydroxide B1 | 3 |
| (b) | damp litmus paper is bleached damp (blue) litmus paper B1 bleached / turns white B1 | 2 |
| (c)(i) | 2H⁺ + 2e⁻ → H₂ 2H⁺ + 2e⁻ B1 → H₂ B1 | 2 |
| (ii) | hydrogen is less reactive than sodium, so H⁺ is discharged hydrogen is less reactive than sodium B1 so H⁺ ions are discharged / gain electrons in preference to Na⁺ B1 | 2 |
| (iii) | H⁺ and Cl⁻ are removed, so OH⁻ and Na⁺ remain H⁺ ions and Cl⁻ ions are removed B1 leaving Na⁺ and OH⁻ ions / sodium hydroxide in solution B1 | 2 |
| (d) | oxygen; Cl⁻ concentration too low, OH⁻ discharged oxygen B1 the concentration of chloride ions is low so hydroxide ions are discharged instead B1 | 2 |
Electrolysis of copper(II) sulfate solution with carbon electrodes.
State what is seen at the cathode and at the anode.
Explain why the blue colour of the solution fades.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | pink/brown copper; bubbles of oxygen cathode: pink/brown copper deposited B1 anode: bubbles of gas (oxygen) B1 | 2 |
| (b) | Cu²⁺ removed copper(II) ions are removed from the solution as copper B1 | 1 |
In the 0620 syllabus, Electrochemistry covers Electrolysis, Hydrogen–oxygen fuel cells.
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Meet Riyaz →Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in