The electrolysis of molten compounds

2 marks · Easy

Write the balanced half-equation for the reaction at the anode during the electrolysis of molten potassium bromide (), and state how many electrons are involved per bromine molecule formed.

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; 2 electrons per Br_2

Also accept: 2Br^- -> Br_2 + 2e^-; 2 electrons

Common mistakes: Br^- -> Br + e^-; Br^- -> Br_2 + e^-

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Marking points

M1 · 1 mark · Writes correct balanced half-equation: .

A1 · 1 mark · States that 2 electrons are involved per Br_2 molecule formed.

Worked solution

At the anode: bromide ions lose electrons.

Each molecule formed involves 2 electrons being lost.