The electrolysis of some other solutions using inert electrodes
3 marks · EasyName the ion that will produce oxygen gas at the anode during the electrolysis of aqueous potassium sulfate solution with inert electrodes.
Write the ionic equation for the formation of oxygen at the anode.
State another negative ion commonly found in salts that will also result in the formation of oxygen at the anode.
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(a) hydroxide ion (OH⁻)
(b) 4OH^− → 2H₂O + O₂ + 4e⁻
(c) nitrate
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Marking points
B1 (a) · 1 mark · Names ‘hydroxide’ or ‘OH⁻’ as the ion that produces oxygen at the anode.
B1 (b) · 1 mark · Gives correct equation: 4OH^- → 2H2O + O2 + 4e^-.
B1 (c) · 1 mark · States another suitable negative ion such as nitrate or sulfate.
Worked solution
a) Hydroxide ion (OH⁻) b) 4OH⁻ → 2H₂O + O₂ + 4e⁻ c) Nitrate (NO₃⁻) or sulfate (SO₄²⁻) will also result in oxygen formation at the anode.