This definitions covers Key Definitions within Electrolysis of Aqueous Solutions for GCSE Chemistry. Revise Electrolysis of Aqueous Solutions in Electrolysis for GCSE Chemistry with 21 exam-style questions and 15 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 5 of 13 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
📖 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⁻
Practice questions for Electrolysis of Aqueous Solutions
When sodium chloride (NaCl) is dissolved in water, which four types of ion are present in the solution?
Describe the three products formed when concentrated brine is electrolysed, and state where each is produced.