Question

State what you would observe when : Copper is added to concentrated nitric acid.

Answer 1

• Copper is the least reactive metal.
• Concentrated nitric acid act as an oxidizing agent.
• When copper is added to concentrated nitric acid, a deep blue solution of aqueous copper nitrate along with a reddish-brown gas of nitrogen dioxide is formed.
• $\underset{\mathrm{Copper}}{\mathrm{Cu}\left(\mathrm{s}\right)}+\underset{\mathrm{Nitric}\mathrm{Acid}}{4{\mathrm{HNO}}_3\left[\mathrm{conc}.\right]\left(\mathrm{aq}\right)}\to \underset{\mathrm{Copper}\mathrm{nitrate}}{\mathrm{Cu}{\left[{\mathrm{NO}}_3\right]}_2\left(\mathrm{aq}\right)}+\underset{\mathrm{Water}}{2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}+\underset{\mathrm{reddish}\mathrm{brown}\mathrm{gas}}{2{\mathrm{NO}}_2\left(\mathrm{g}\right)}$