Electrolysis half equations to learn

copper chloride (aq)

ions present:

Cu²⁺, Cl⁻, H⁺, OH⁻

anode reaction:

2Cl⁻ → Cl₂ + 2e⁻

cathode reaction:

Cu²⁺ + 2e⁻ → Cu

sodium chloride (aq)

ions present:

Na⁺, Cl⁻, H⁺, OH⁻

anode reaction:

2Cl⁻ → Cl₂ + 2e⁻

cathode reaction:

2H⁺ + 2e⁻ → H₂

sodium sulphate (aq)

ions present:

Na⁺, SO₄²⁻, H⁺, OH⁻

anode reaction:

4OH⁻ → O₂ + H₂O + 4e⁻

cathode reaction:

2H⁺ + 2e⁻ → H₂

water acidified with sulphuric acid (H₂SO₄)

ions present:

H⁺, OH⁻, SO₄²⁻

anode reaction:

4OH⁻ → O₂ + H₂O + 4e⁻

cathode reaction:

2H⁺ + 2e⁻ → H₂

molten lead bromide

ions present:

Pb²⁺, Br⁻

anode reaction:

2Br ⁻ → Br₂ + 2e⁻

cathode reaction:

Pb²⁺ + 2e⁻ → Pb