WAEC Chemistry 2015 Paper

Concept:Sodium displaces the acidic hydrogen of the hydroxyl group in ethanol, releasing hydrogen gas.Explanation:Ethanol contains an $-\mathrm{OH}$ group attached to its carbon chain.Sodium reacts with ethanol by replacing the hydrogen of this $-\mathrm{OH}$ group.The reaction is:$$2\mathrm{C}_2\mathrm{H}_5\mathrm{OH} + 2\mathrm{Na} \rightarrow 2\mathrm{C}_2\mathrm{H}_5\mathrm{ONa} + \mathrm{H}_2$$Here, $\mathrm{C}_2\mathrm{H}_5\mathrm{ONa}$ is sodium ethoxide, and $\mathrm{H}_2$ is hydrogen gas.This evolved gas burns with a characteristic pop sound, confirming it is hydrogen.Answer:B. Hydrogen