Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
The electrolysis of molten compounds
19 practice questions
Practice questions
1–8 of 8 · Normal
Question 1
2 marks · Normal
Answer and see the solution →State the products formed at the electrodes when molten sodium chloride is electrolysed. For each product, name the electrode where it forms.
Question 2
4 marks · Normal
Answer and see the solution →Aluminium oxide can be electrolysed when molten.
(a)[1 mark]State the names and formulas of the ions present in molten aluminium oxide.
(b)[1 mark]Write the half-equation for the reaction at the cathode.
(c)[1 mark]Write the half-equation for the reaction at the anode.
(d)[1 mark]Identify the product formed at each electrode.
Question 3
4 marks · Normal
Answer and see the solution →A student investigates the electrolysis of three different molten ionic compounds using carbon electrodes. The table below shows the ions present in each compound.
Compound Cation(s) Anion(s) Magnesium bromide (MgBr2) Mg^{2+} Br^- Potassium iodide (KI) K^+ I^- Calcium chloride (CaCl2) Ca^{2+} Cl^- (a)[1 mark]For magnesium bromide, state the product formed at the anode.
(b)[1 mark]For potassium iodide, state the product formed at the cathode.
(c)[2 marks]Write the half-equation for the reaction at the anode when calcium chloride is electrolysed.
Question 4
1 mark · Normal
Answer and check →Which of the following half-equations correctly represents the reaction occurring at the anode during the electrolysis of molten potassium bromide (KBr)?
- A.Br^- → Br_2 + 2e^-
- B.K^+ + e^- → K
- C.2Br^- → Br_2 + 2e^-
- D.K^+ → K + e^-
Question 5
2 marks · Normal
Answer and see the solution →Write the half-equation for the reaction at the cathode during the electrolysis of molten zinc chloride (ZnCl_2). State what is observed at the cathode.
Question 6
4 marks · Normal
Answer and see the solution →The diagram below shows the electrolysis of molten copper(II) bromide (CuBr2) using carbon electrodes.
Apparatus for electrolysis of molten copper(II) bromide. (a)[1 mark]Identify the ions present in molten copper(II) bromide.
(b)[1 mark]State what is produced at the cathode and at the anode.
(c)[1 mark]Write the half-equation for the reaction at the cathode.
(d)[1 mark]Describe a visible change that would be observed at the anode during electrolysis.
Question 7
3 marks · Normal
Answer and see the solution →Molten sodium chloride (NaCl) is electrolysed using inert electrodes.
(a)[1 mark]State the ions present in molten sodium chloride.
(b)[1 mark]Write the balanced half-equation for the reaction at the cathode.
(c)[1 mark]Identify the product formed at the anode and write the half-equation for its formation.
Question 8
3 marks · Normal
Answer and see the solution →Electrolysis is carried out on molten magnesium chloride (MgCl2) using inert electrodes.
(a)[1 mark]Predict the product formed at the anode. Explain your answer.
(b)[1 mark]Write a balanced half-equation for the reaction at the cathode.
(c)[1 mark]Explain why molten magnesium chloride conducts electricity, but solid magnesium chloride does not.