Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
The electrolysis of sodium chloride solution
19 practice questions
Practice questions
1–10 of 19
Question 1
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 2
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 3
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 4
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 5
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 6
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 7
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 8
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.
Question 9
2 marks · Normal
Answer and see the solution →During the electrolysis of sodium chloride solution, hydrogen gas is produced at the cathode rather than sodium metal.
Explain why sodium ions do not gain electrons at the cathode, but hydrogen ions do.
Question 10
4 marks · Normal
Answer and see the solution →In the electrolysis of sodium chloride solution, hydrogen gas forms at the cathode.
(a)[1 mark]State the ions present in sodium chloride solution that move to the cathode.
(b)[2 marks]Write a balanced half-equation to show the reaction occurring at the cathode. (You may use either half-equation involving H+ or H2O.)
(c)[1 mark]Explain, in one sentence, what happens to the electrons at the cathode during this reaction.