Electrolysis: brine
I can describe the reactions of electrolysis of an aqueous solution of sodium chloride, including the tests for identifying the products.
Electrolysis: brine
I can describe the reactions of electrolysis of an aqueous solution of sodium chloride, including the tests for identifying the products.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- There are four ions present in a solution of brine: H⁺, OH⁻, Na⁺ and Cl⁻.
- The product at the negative electrode is hydrogen gas.
- The product at the positive electrode is chlorine gas.
- Sodium hydroxide solution forms in the electrolyte solution, making it alkaline.
- Two types of ions are in competition at each electrode.
Keywords
Brine - A concentrated aqueous solution containing between 3.5% and 26% sodium chloride.
Anode - A positively charged electrode, in an electrolysis cell, to which the anions are attracted.
Cathode - A negatively charged electrode, in an electrolysis cell, to which the cations are attracted.
Reduction - Reduction is a type of reaction in which a substance loses oxygen or gains electrons.
Oxidation - Oxidation is a type of reaction in which a substance gains oxygen or loses electrons.
Common misconception
Pupils find it hard to remember what is formed at each electrode.
Remind pupils about the electrolysis rules and provide opportunities for them to apply the rules to different electrolytes. Use animations to show the ions present in brine and how they move in the electrolysis cell.
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
Lesson video
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