This definitions covers Key Definitions within Electrolysis of Aqueous Solutions for GCSE Chemistry. Revise Electrolysis of Aqueous Solutions in Electrolysis for GCSE Chemistry with 20 exam-style questions and 0 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 5 of 12 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
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Section 5 of 12
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20 questions
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📖 Key Definitions
Aqueous solution: A substance dissolved in water. In electrolysis of aqueous solutions, both the ions from the dissolved salt AND H⁺ and OH⁻ ions from water are present.
Preferential discharge: When two ions compete at an electrode, the one that is more easily reduced (at cathode) or more easily oxidised (at anode) is discharged first.
Discharge: When an ion gains or loses electrons at an electrode and becomes a neutral atom or molecule — it is "discharged" from ionic to uncharged form.
Brine: A concentrated solution of sodium chloride (salt) in water. Electrolysis of brine produces hydrogen, chlorine, and sodium hydroxide — the chlor-alkali industry.
Half equation (cathode for H₂): 2H⁺ + 2e⁻ → H₂
Half equation (anode for O₂): 4OH⁻ → O₂ + 2H₂O + 4e⁻