Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Electrolysis
198 practice questions
Topics covered
- Why things conduct electricity17 practice questions
- Passing electricity through compounds: electrolysis20 practice questions
- The electrolysis of molten compounds19 practice questions
- Electrolysis and redox19 practice questions
- The electrolysis of other molten substances19 practice questions
- The electrolysis of aqueous solutions18 practice questions
- The electrolysis of sodium chloride solution19 practice questions
- The electrolysis of copper(ii) sulfate solution using inert electrodes18 practice questions
- The electrolysis of some other solutions using inert electrodes19 practice questions
- What would happen with non-electrolytes?19 practice questions
Practice questions
11–20 of 33 · Hard
Question 11
5 marks · Hard
Answer and see the solution →The apparatus below is used to electrolyse molten tin(II) chloride (SnCl₂). Tin(II) ions (Sn²⁺) and chloride ions (Cl⁻) move towards the electrodes and react.
Electrolysis setup for molten tin(II) chloride (a) State what is meant by 'discharging' a tin(II) ion during the electrolysis of molten tin(II) chloride.
(a)[2 marks]State what is meant by 'discharging' a tin(II) ion during the electrolysis of molten tin(II) chloride.
(b)[2 marks]Explain, in terms of electron transfer, what happens to a tin(II) ion at the cathode in this process.
(c)[1 mark]Write a half-equation for the reaction involving tin(II) ions at the cathode.
Question 12
2 marks · Hard
Answer and see the solution →The electrolysis of molten iron(III) chloride (FeCl₃) involves reactions at both electrodes.
State which electrode reaction involves oxidation, and which involves reduction. Explain your answer with reference to loss or gain of electrons.
Question 13
2 marks · Hard
Answer and see the solution →Balance the following ionic half-equation for the electrolysis of a molten ionic compound, so that both the number of atoms and the charges are equal on both sides:
where M represents a generic metal.
Question 14
5 marks · Hard
Answer and see the solution →A molten ionic compound XY is electrolysed using inert electrodes.
(a)[2 marks]State which element is produced at the cathode. Explain your answer.
(b)[2 marks]State which element is produced at the anode. Explain your answer.
(c)[1 mark]Give one reason why these predictions are valid only for molten binary ionic compounds, not aqueous ones.
Question 15
2 marks · Hard
Answer and see the solution →Write the ionic half-equation for the reaction that occurs at the cathode during the electrolysis of molten magnesium oxide (MgO).
Question 16
2 marks · Hard
Answer and see the solution →Describe two essential safety precautions you must take when setting up an experiment to investigate the electrolysis of concentrated sodium chloride solution in the laboratory.
Question 17
5 marks · Hard
Answer and see the solution →A student carries out the electrolysis of concentrated sodium chloride solution using carbon electrodes as shown below.
Electrolysis of concentrated sodium chloride solution (a)[1 mark]State the product formed at the cathode.
(b)[1 mark]State the product formed at the anode.
(c)[1 mark]Write the half-equation for the reaction at the cathode.
(d)[1 mark]Write the half-equation for the reaction at the anode.
(e)[1 mark]Explain why hydrogen forms at the cathode instead of sodium.
Question 18
2 marks · Hard
Answer and see the solution →During the electrolysis of concentrated sodium chloride solution, the volume of chlorine gas collected at the anode is often less than the volume expected. Explain two reasons for this observation.
Question 19
2 marks · Hard
Answer and see the solution →Write a balanced half-equation, including state symbols, for the reduction that takes place at the cathode during the electrolysis of sodium chloride solution. State the physical state of each species involved.
Question 20
5 marks · Hard
Answer and see the solution →A student sets up an electrolytic cell using sodium chloride solution and collects the gases produced. They notice that the solution near the cathode becomes increasingly alkaline as the reaction proceeds.
(a)[1 mark]Name the ion that increases in concentration around the cathode.
(b)[2 marks]Write a balanced chemical equation, with state symbols, for the process at the cathode that explains this change.
(c)[2 marks]Explain why the solution near the cathode becomes alkaline as electrolysis continues. Relate your answer to the ions produced and removed at the electrode.