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
71–80 of 80 · Easy
Question 71
2 marks · Easy
Answer and see the solution →Explain why sodium chloride conducts electricity when molten, but not as a solid.
Question 72
3 marks · Easy
Answer and see the solution →A student tests three substances for their ability to conduct electricity when solid and when dissolved in water. The results are shown in the table.
Conductivity results Substance Conducts as a solid? Conducts dissolved in water? A (potassium bromide) No Yes B (ethanol) No No C (magnesium) Yes n/a (a)[2 marks]Identify substances A, B, and C as ionic, covalent, or metallic.
(b)[1 mark]Which substance is a non-electrolyte?
Question 73
1 mark · Easy
Answer and see the solution →Name a common non-electrolyte used in food and explain why it does not conduct electricity.
Question 74
3 marks · Easy
Answer and see the solution →The table gives the results for the electrical conductivity of three substances in different states:
Conductivity results for different substances Substance Solid Molten Aqueous D No Yes Yes E No No No F Yes Yes n/a (a)[1 mark]Which substance is a non-electrolyte? Explain your answer.
(b)[1 mark]What type of bonding does substance D have? Explain using the data.
(c)[1 mark]State the bonding present in substance F.
Question 75
2 marks · Easy
Answer and see the solution →A student tests solid sodium chloride and sugar for electrical conductivity. She finds that only molten sodium chloride conducts electricity, while sugar does not conduct electricity when molten or in solution.
State, with a reason, whether each substance is ionic, covalent, or a non-electrolyte.
(a)[1 mark]Sodium chloride:
(b)[1 mark]Sugar:
Question 76
2 marks · Easy
Answer and see the solution →The results of an experiment are shown below:
Conductivity Results Substance State Tested Conducts Electricity? Magnesium chloride Solid No Magnesium chloride Molten Yes Ethanol Liquid No Identify whether each substance is ionic, covalent, or a non-electrolyte. Give a reason for your answer in each case.
(a)[1 mark]Magnesium chloride:
(b)[1 mark]Ethanol:
Question 77
5 marks · Easy
Answer and see the solution →The table shows some properties of substances at room temperature.
(a)Substance Properties Substance Type of Bonding Solid? (yes/no) Molten? (yes/no) In solution? (yes/no) Conducts electricity? (yes/no) Copper Metallic Yes No No Yes Sodium chloride (NaCl) Ionic Yes Yes Yes No Methane (CH4) Covalent Yes No No No (i)[1 mark]State one reason why copper conducts electricity as a solid.
(ii)[1 mark]Give one reason why solid sodium chloride does not conduct electricity.
(iii)[1 mark]Explain how sodium chloride can be made to conduct electricity.
(b)You pass electricity through molten sodium chloride using a simple cell and two inert (carbon) electrodes.
(i)[1 mark]In this experiment, what is the name given to the liquid sodium chloride?
(ii)[1 mark]State the name given to the positive electrode and the negative electrode.
Question 78
5 marks · Easy
Answer and see the solution →A student compares the electrolysis of molten lead(II) bromide with the electrolysis of aqueous sodium chloride solution.
(a)[2 marks]State the product formed at the cathode during the electrolysis of molten lead(II) bromide. Explain your answer briefly.
(b)[3 marks]Describe how to set up the apparatus to investigate the electrolysis of an aqueous sodium chloride solution. State one safety precaution.
Question 79
5 marks · Easy
Answer and see the solution →This question is about balancing half-equations for the electrolysis of ionic compounds.
(a)[2 marks]Write the balanced ionic half-equation (including state symbols) for the reaction at the anode during the electrolysis of molten zinc(II) chloride.
(b)[2 marks]State the product formed at the anode and the product formed at the cathode during the electrolysis of concentrated aqueous sodium chloride solution.
(c)[1 mark]Explain why less chlorine gas is collected at the anode than expected, even if the reaction has gone to completion.
Question 80
5 marks · Easy
Answer and see the solution →A student investigates the electrolysis of two different substances using graphite electrodes:
(a)[2 marks]Molten lead(II) bromide (PbBr₂) is electrolysed. Predict which element forms at the cathode and which at the anode. Explain how you know.
(b)The student now electrolyses concentrated aqueous magnesium chloride (MgCl₂(aq)). After testing the gases, they find the volume of chlorine gas collected at the anode is much less than the volume of hydrogen collected at the cathode.
(i)[1 mark]Explain why hydrogen, and not magnesium, is formed at the cathode.
(ii)[2 marks]Give a reason why less chlorine gas is collected at the anode than expected.