Question

Dilute $HCl$ does not react with $Cu$ but dilute $H{NO}_3$ reacts with $Cu$. Give reason.

• A. $HCl$ is a good oxidising agent
• B. $HCl$ is a weak acid
• C. $H{NO}_3$ is a good oxidising agent
• D. $H{NO}_3$ is a strong acid

Answer 1

Answer: (C)

$H{NO}_3$ is a good oxidising agent

Copper is an unreactive metal and does not react in normal circumstances with dilute acids. In the reaction between copper and nitric acid, nitric oxide gas NO is produced. Nitric acid is a very strong oxidising agent and the copper is oxidized to copper ions and the solution turns from colorless to red and a cloud of red toxic gas of NO evolves and hence whole copper is consumed in the reaction.