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Topic Summary: Electrolysis of Aqueous Solutions

Part of Electrolysis of Aqueous Solutions — GCSE Chemistry

This topic summary covers Topic Summary: Electrolysis of Aqueous Solutions 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 13 of 13 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 13 of 13

Practice

20 questions

Recall

0 flashcards

Topic Summary: Electrolysis of Aqueous Solutions

Key Terms
  • Aqueous solution — contains ions from salt + H⁺/OH⁻ from water
  • Preferential discharge — one ion reacts rather than another
  • Brine — concentrated NaCl solution
  • Cathode — negative electrode (reduction)
  • Anode — positive electrode (oxidation)
Must-Know Facts
  • 4 ions always present in aqueous solution
  • Cathode: metal above H → H₂; below H → metal
  • Anode: halide present → halogen; no halide → O₂
  • Brine → H₂ + Cl₂ + NaOH
  • 2H⁺ + 2e⁻ → H₂ (cathode half equation)
  • 4OH⁻ → O₂ + 2H₂O + 4e⁻ (anode, no halide)
  • Gas tests: H₂ = squeaky pop; Cl₂ = bleaches litmus

Keep building this topic

Read this section alongside the surrounding pages in Electrolysis of Aqueous Solutions. That gives you the full topic sequence instead of a single isolated revision point.

Exam Tips for Electrolysis of Aqueous SolutionsThe Water ComplicationElectrolysis of Brine

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?

  • A. Na⁺, Cl⁻, H⁺ and OH⁻
  • B. Na⁺, Cl⁻, H₂O and OH⁻
  • C. Na⁺, Cl⁻ only
  • D. Na⁺, Cl⁻, H₂ and O²⁻
1 markfoundation

Describe the three products formed when concentrated brine is electrolysed, and state where each is produced.

3 marksstandard

Quick Recall Flashcards

State the anode rule for aqueous electrolysis.
If a halide ion (Cl⁻, Br⁻, or I⁻) is present → the halogen gas forms. If NO halide is present → oxygen gas forms from the OH⁻ ions. Example: Cl⁻ present → Cl₂ forms. SO₄²⁻ present (no halide) → O₂ forms.
State the cathode rule for aqueous electrolysis.
If the metal is MORE reactive than hydrogen (above H in reactivity series) → hydrogen gas forms. If the metal is LESS reactive than hydrogen (below H) → the metal deposits. Examples: Na above H → H₂ forms. Cu below H → Cu deposits.

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Electrolysis of Aqueous Solutions