Cambridge IGCSE Chemistry
4.1Electrolysis
Electrolysis in Cambridge IGCSE Chemistry: what the syllabus expects you to know, the learning objectives and how to practise.
Subtopic63 practice questions3 lessons
Learning objectives
What the syllabus expects you to be able to do.
- 4.1.1Define electrolysis as the breaking down of an ionic compound, molten or in aqueous solution, by passing an electric current through it.
- 4.1.2Identify the anode (positive electrode), the cathode (negative electrode) and the electrolyte (the molten or aqueous substance being electrolysed) in a simple electrolytic cell.
- 4.1.3Identify the products at each electrode, and describe what is observed, when molten lead(II) bromide, concentrated aqueous sodium chloride and dilute sulfuric acid are electrolysed with inert platinum or carbon (graphite) electrodes.
- 4.1.4State that metals or hydrogen form at the cathode and that non-metals other than hydrogen form at the anode.
- 4.1.5Predict the products at each electrode when a molten binary compound is electrolysed.
- 4.1.6State that metal objects are electroplated to improve their appearance and their resistance to corrosion.
- 4.1.7Describe how a metal object is electroplated.
- 4.1.8Supplement: describe how charge is transferred during electrolysis: electrons moving in the external circuit, electrons lost or gained at the electrodes and ions moving in the electrolyte.
- 4.1.9Supplement: identify the products, and describe the observations, when aqueous copper(II) sulfate is electrolysed with inert carbon (graphite) electrodes and with copper electrodes.
- 4.1.10Supplement: predict the products at each electrode when dilute or concentrated aqueous solutions of halides are electrolysed.
- 4.1.11Supplement: write ionic half-equations for the reactions at the anode (oxidation) and at the cathode (reduction).
Lessons
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Electrolysis of aqueous solutions
40 min
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Electrolysis: principles and molten compounds
35 min
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Electroplating and the purification of copper
35 min
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Sample question
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Turn Electrolysis into a strength.
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