Question

Small pieces of a silver coloured metal X, were added to concentrated nitric acid A then brown gas Z and a colourless solution containing salt Y were formed Identify X, Y and Z.

Answer 1

The silver metal reacts with hot concentrated Nitric acid and produces Silver Nitrate (AgNO₃) salt, Nitrogen dioxide (NO₂) gas, and water as products.

1. This reaction is a redox reaction (oxidation-reduction reaction).
2. Silver is not a reactive metal like other metals such as iron, calcium, and sodium.
3. Concentrated Nitric acid has oxidizing acid characteristics like concentrated nitric acid. That is the reason why Concentrated Nitric acid reacts with silver metal.
4. In this reaction, silver is oxidized to +1 oxidation state of silver, and nitric acid is reduced to +4 oxidation state from +5 oxidation state.
5. During the reaction, brown-colored nitrogen dioxide (NO₂) gas is emitted.

Equation of reaction between Silver (Ag) concentrated Nitric acid(HNO₃).

$\underset{\mathrm{Silver}}{\mathrm{Ag}\left(\mathrm{s}\right)}+\underset{\mathrm{Concentrated}\mathrm{Nitric}\mathrm{acid}}{2{\mathrm{HNO}}_3\left(\mathrm{conc}\right)}\to \underset{\mathrm{Silver}\mathrm{Nitrate}}{{\mathrm{AgNO}}_3\left(\mathrm{s}\right)}+\underset{\mathrm{Nitrogen}\mathrm{dioxide}}{{\mathrm{NO}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

Final answer: Silver metal reacts with hot concentrated Nitric acid and produces Silver Nitrate (AgNO₃) salt, Nitrogen dioxide (NO₂) gas (brown in color ), and water as products. Hence X is Silver metal, Y is Silver Nitrate (AgNO₃) salt, and Z is Nitrogen dioxide (NO₂) gas.