Question

(a) Explain the following in terms of gain or loss of oxygen with one example each
(i) oxidation (ii) reduction
(b) When copper powder is heated strongly in air, it forms copper oxide. Write a balanced chemical equation for this reaction. Name (i) substance oxidised, and (ii) substance reduced.

Answer 1

Explanation:

(a) Gain or loss of oxygen:

(i) Oxidation:

• The oxidation process involves gain of oxygen. The compound which oxidizes is called oxidizing agent.

(ii) Reduction:

• The reduction process involves loss of oxygen. The compound which reduces is called reducing agent.

(b) Copper powder reaction:

$2 C u_{(s)}+O_{2(g)} \rightarrow 2 C u O_{(s)}$

• When copper reddish brown metal powder is heated, it reacts with air to form copper oxide which is black in colour.

• (i) The substance oxidised is copper $(Cu)$.
• (ii) The substance reduced is oxygen$(O_2)$.