4.1 Electrolysis

2026 Syllabus Objectives

Core:

1. Define electrolysis as the decomposition of an ionic compound, when molten or in aqueous solution, by the passage of an electric current
2. Identify in simple electrolytic cells: (a) the anode as the positive electrode (b) the cathode as the negative electrode (c) the electrolyte as the molten or aqueous substance that undergoes electrolysis
3. Identify the products formed at the electrodes and describe the observations made during the electrolysis of: (a) molten lead(II) bromide (b) concentrated aqueous sodium chloride (c) dilute sulfuric acid using inert electrodes made of platinum or carbon/graphite
4. State that metals or hydrogen are formed at the cathode and that non-metals (other than hydrogen) are formed at the anode
5. Predict the identity of the products at each electrode for the electrolysis of a binary compound in the molten state
6. State that metal objects are electroplated to improve their appearance and resistance to corrosion
7. Describe how metals are electroplated

Supplement: 8. Describe the transfer of charge during electrolysis to include: (a) the movement of electrons in the external circuit (b) the loss or gain of electrons at the electrodes (c) the movement of ions in the electrolyte 9. Identify the products formed at the electrodes and describe the observations made during the electrolysis of aqueous copper(II) sulfate using inert carbon/graphite electrodes and when using copper electrodes 10. Predict the identity of the products at each electrode for the electrolysis of a halide compound in dilute or concentrated aqueous solution 11. Construct ionic half-equations for reactions at the anode (to show oxidation) and at the cathode (to show reduction)

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