Question

Identify the anion present in the following compounds.

Compound X on heating with copper turnings and concentrated sulphuric acid liberates a reddish-brown gas.

Answer 1

1. The anion present in the compound is the Nitrate ion,${\mathrm{NO}}_3^{-}$.
2. On heating, a Nitrate ion-containing compound with Copper turnings and concentrated Sulphuric acid (${\mathrm{H}}_2{\mathrm{SO}}_4$), liberates a reddish-brown gas called Nitrogen Dioxide (${\mathrm{NO}}_2$).

$$\begin{gathered} 2{\mathrm{NO}}_3^{-}+4{\mathrm{H}}_2{\mathrm{SO}}_4+\underset{\text{Copper}}{3\mathrm{Cu}}\to \underset{\text{Copperlon}}{3{\mathrm{Cu}}^{2+}}+\underset{\text{NitricOxide}}{2\mathrm{NO}}+\underset{\text{Sulphate lon}}{4{\mathrm{SO}}_4^{2-}}+\underset{\text{Water}}{4{\mathrm{H}}_2}\mathrm{O} \\ \underset{\text{NitricOxide}}{2\mathrm{NO}}+\underset{\text{Oxygen}}{{\mathrm{O}}_2}\to \underset{\text{NitrogenDioxide}}{2{\mathrm{NO}}_2}\text{(reddish-brown gas)} \end{gathered}$$