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2017 O Level Chem P1 Q13 — Electrolysis / Products of Electrolysis Solution

Electrolysis / Products of Electrolysis 2017 O Level Pure Chemistry · Paper 1 · Q13

Question

Dilute aqueous sodium chloride and concentrated aqueous sodium chloride are electrolysed using inert electrodes in separate experiments. Which row shows the products of these experiments? Question diagram

Question diagram

A
B
C
D

Correct answer: C

Video Solution

Explanation

Answer: C. With dilute sodium chloride the products are oxygen at the positive electrode (water is oxidised in preference to the dilute chloride) and hydrogen at the negative electrode.

With concentrated sodium chloride the high chloride concentration gives chlorine at the positive electrode, while hydrogen is still produced at the negative electrode. So dilute gives oxygen and hydrogen; concentrated gives chlorine and hydrogen.

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