Describe the reactions during the electrolysis of waterA) Oxygen is reduced and hydrogen is oxidized. B) Oxygen and hydrogen are both oxidized. C) Oxygen and hydrogen are both reduced. D) Oxygen is oxidized and hydrogen is reduced. E) Neither oxygen or hydrogen are oxidized or reduced.

D) Oxygen is oxidized and hydrogen is reduced.

Explanation:

In the electrolysis of water, an electric current passes through an electrolytic solution (e. g. aqueous NaCl), leading to the following redox reaction.

H₂O (l) → H₂ (g) + 1/2 O₂ (g)

The corresponding half-reactions are:

Reduction: 2 H₂O (l) + 2 e⁻ → H₂ (g) + 2 OH⁻

Oxidation: 2 H₂O (l) → O₂ (g) + 4 H⁺ (aq) + 4 e⁻

As we can see, H in water is reduced (its oxidation number decreases from 1 to 0), while O in water is oxidized (its oxidation number increases from - 2 to 0).