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 85 · Normal
Question 71
2 marks · Normal
Answer and see the solution →Name the gases formed at the anode and at the cathode when dilute sulfuric acid is electrolysed with inert electrodes.
Question 72
4 marks · Normal
Answer and see the solution →A student electrolyses aqueous magnesium sulfate using inert electrodes.
(a)[1 mark]State the gas formed at the cathode.
(b)[2 marks]Explain why this product is formed at the cathode, using the reactivity series.
(c)[1 mark]Name the ion that is discharged at the anode.
Question 73
3 marks · Normal
Answer and see the solution →A student electrolyses an aqueous solution of sodium sulfate using inert electrodes.
She collects 120 cm³ of gas at the anode over a period of time.
Only two types of negative ions are present: sulfate ions and hydroxide ions.
State which ion is discharged at the anode, write the ionic equation for the reaction, and calculate the volume of oxygen molecules produced in moles (to 2 significant figures). (1 mol of any gas occupies 24 000 cm³ at room temperature and pressure.)
(a)[1 mark]State which ion is discharged at the anode.
(b)[1 mark]Write the ionic half-equation for the reaction at the anode.
(c)[1 mark]Calculate the amount of oxygen produced, in moles, to 2 significant figures.
Question 74
2 marks · Normal
Answer and see the solution →A student wants to know whether glucose (C6H12O6) is an electrolyte, an ionic compound, or a covalent compound. They attempt to pass an electric current through both solid glucose and glucose dissolved in water, but the bulb does not light up in either case.
State what type of substance glucose is and give a reason based on the results of the experiment.
Question 75
4 marks · Normal
Answer and see the solution →Two students investigate the ability of different substances to conduct electricity using the apparatus below.
(a)[2 marks]Complete the table below by identifying whether each substance is likely to conduct electricity or not in the form stated.
Substance State Will it conduct electricity? (Yes/No) Sodium chloride Molten Sucrose (C12H22O11) Aqueous solution (b)[2 marks]Explain why one of these substances does not conduct electricity in the given state.
Question 76
3 marks · Normal
Answer and see the solution →Water is often used as the solvent in electrolysis experiments. Pure water conducts electricity only very weakly, but when a small amount of sodium chloride is added, it conducts electricity much better.
Explain why pure water is a poor conductor of electricity and why adding sodium chloride increases the conductivity so much.
Question 77
4 marks · Normal
Answer and see the solution →The table below shows results from an experiment where a student measured the volume of oxygen gas produces at the anode when different substances are electrolysed:
Results of electrolysis Substance (aq) Bulb lights? Volume of O2 at anode (cm³) Sodium sulfate Yes 18.5 Copper(II) sulfate Yes 17.8 Sugar No 0 Ethanol No 0 (a)[2 marks]Identify which substances are electrolytes and which are non-electrolytes. Explain your choices.
(b)[2 marks]State what this experiment shows about the type of bonding in sugar and ethanol.
Question 78
1 mark · Normal
Answer and check →The student sets up an apparatus to test substance X for electrical conductivity. The bulb stays off, and even after substance X is dissolved in water, there is still no current. What does this suggest about substance X?
- A.It is an ionic compound that conducts electricity when solid.
- B.It is a covalent compound that forms ions in water.
- C.It is a non-electrolyte and does not produce ions in solution.
- D.It is an acid and must form ions in solution.
Question 79
2 marks · Normal
Answer and see the solution →Explain why potassium iodide (KI) will conduct electricity when molten but not as a solid.
Question 80
4 marks · Normal
Answer and see the solution →You are given a white solid (substance Y) that is soluble in water. You need to determine whether it is an ionic compound, a covalent compound, or a non-electrolyte.
(a)[2 marks]Describe an experiment you could do to determine the type of substance.
(b)[2 marks]State what you would observe if substance Y is an ionic compound and explain your answer.