Key Facts to Memorise
Part of Electrolysis of Aqueous Solutions — GCSE Chemistry
This key facts covers Key Facts to Memorise 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 6 of 12 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 6 of 12
Practice
20 questions
Recall
0 flashcards
📌 Key Facts to Memorise
- Aqueous solutions have 4 ions: 2 from the dissolved compound + H⁺ and OH⁻ from water
- Cathode rule: Metal above H → hydrogen forms; Metal below H → metal forms
- Anode rule: Halide present → halogen forms; No halide → oxygen forms
- CuSO₄ solution products: Copper at cathode (Cu below H) + Oxygen at anode (sulfate not a halide)
- NaCl solution products: Hydrogen at cathode (Na above H) + Chlorine at anode (chloride is a halide)
- Half equation for H₂: 2H⁺ + 2e⁻ → H₂
- Half equation for O₂: 4OH⁻ → O₂ + 2H₂O + 4e⁻
- Gas tests: H₂ = squeaky pop with lighted splint; O₂ = relights glowing splint; Cl₂ = bleaches damp litmus paper white
- Brine electrolysis makes H₂ + Cl₂ + NaOH (three valuable products!)
Quick Check: When copper sulfate solution (CuSO₄) is electrolysed, what forms at the cathode and why?
Copper metal deposits at the cathode. Copper is below hydrogen in the reactivity series, so Cu²⁺ ions are preferentially discharged over H⁺ ions. The Cu²⁺ ions gain 2 electrons: Cu²⁺ + 2e⁻ → Cu.