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chemistry igcse acapprinted 27 · PDF 27
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27
Electrolysis of Dilute Sulfuric Acid
At Cathode: Hydrogen ions (H⁺) are reduced to form hydrogen gas.
Half-equation: 2H⁺ + 2e⁻ → H₂(g)
At Anode: Hydroxide ions (OH⁻) are oxidized to form oxygen gas.
Half-equation: 4OH⁻ → O₂(g) + 2H₂O + 4e⁻
Products: Hydrogen gas at cathode, oxygen gas at anode.
Electrolysis of Water
Water is split into hydrogen and oxygen gases.
At Cathode: Hydrogen ions (H⁺) are reduced to form hydrogen gas.
Half-equation: 2H⁺ + 2e⁻ → H₂(g)
At Anode: Hydroxide ions (OH⁻) are oxidized to form oxygen gas.
Half-equation: 4OH⁻ → O₂(g) + 2H₂O + 4e⁻
Overall Reaction: 2H₂O(l) → 2H₂(g) + O₂(g)