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
111–120 of 198
Question 111
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 112
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 113
1 mark · Easy
Answer and see the solution →During the electrolysis of sodium chloride solution, what ion builds up near the cathode making the solution there alkaline?
Question 114
3 marks · Easy
Answer and see the solution →A student electrolyses sodium chloride solution and is surprised that hydrogen, not sodium, is produced at the cathode.
(a)[1 mark]Name the two positive ions present in the solution that could be discharged at the cathode.
(b)[1 mark]State which of these ions is discharged and forms a gas at the cathode.
(c)[1 mark]Explain why sodium ions are not discharged at the cathode.
Question 115
2 marks · Easy
Answer and see the solution →Write a balanced half-equation for the cathode reaction during the electrolysis of sodium chloride solution when hydrogen gas is formed.
Question 116
2 marks · Easy
Answer and see the solution →Describe why the region near the cathode becomes alkaline during the electrolysis of sodium chloride solution.
Question 117
3 marks · Easy
Answer and see the solution →The table shows the tendency to gain electrons (ease of reduction) for some ions in decreasing order.
Reduction Tendency of Some Ions Ion Reduction Tendency K^+ Very difficult Na^+ Very difficult Ca^2+ Difficult H^+ Easier Cu^2+ Very easy A student electrolyses sodium chloride solution. Use the data to answer the following questions.
(a)[1 mark]Suggest which ion, Na⁺ or H⁺, is more easily reduced at the cathode.
(b)[1 mark]Which gas is formed at the cathode?
(c)[1 mark]Explain why sodium metal does not form at the cathode, using the reduction tendency data.
Question 118
1 mark · Easy
Answer and see the solution →What is the symbol equation for the reduction of hydrogen ions at the cathode during electrolysis of sodium chloride solution?
Question 119
3 marks · Easy
Answer and see the solution →During the electrolysis of sodium chloride solution, a student notices the solution near the cathode becomes alkaline.
(a)[1 mark]Name the ion that increases in concentration near the cathode.
(b)[1 mark]Write the half-equation that shows the production of hydrogen gas at the cathode.
(c)[1 mark]Explain why the increase of this ion causes the solution to become alkaline.
Question 120
2 marks · Easy
Answer and see the solution →At the cathode during the electrolysis of sodium chloride solution, two different possible ions could gain electrons. Use the position of sodium and hydrogen in the reactivity series to deduce which ion is discharged.