In the reduction of copper(II) oxide by hydrogen, which of the following species is oxidised during the reaction?

The correct option is Hydrogen.

Explanation

In chemical reactions, oxidation is defined as the gain of oxygen or the loss of hydrogen by a substance. Conversely, reduction is defined as the loss of oxygen or the gain of hydrogen. Reactions where both oxidation and reduction occur simultaneously are termed redox reactions.

Analysis of the Reaction:

The chemical equation for the reduction of copper(II) oxide by hydrogen is:

CuO + H₂ → Cu + H₂O

• Copper(II) oxide (CuO): This compound loses oxygen to become copper (Cu). The loss of oxygen constitutes reduction. Therefore, CuO is reduced.
• Hydrogen (H₂): This element gains oxygen to form water (H₂O). The gain of oxygen constitutes oxidation. Therefore, Hydrogen is oxidised.

Key Takeaway:

The substance that gains oxygen during a reaction is said to be oxidised, while the substance that loses oxygen is said to be reduced.