Question

What happens when (given balanced equation):
(a) Sulphur is added to hot and conc. HNO₃?
(b) Nitric acid is added to KI (aq)?
(c) Nitric acid is dissolved in large amount of water?
(d) Nitric acid is added to washing soda and the resulting gas is passed through a freshly prepared lime water?
(e) Limestone reacts with nitric acid?

Answer 1

1. This will result in the formation of sulphuric acid, as shown below.

$$\begin{gathered} 2{\mathrm{HNO}}_3\to {\mathrm{H}}_2\mathrm{O}+2{\mathrm{NO}}_2+\left[\mathrm{O}\right] \\ \mathrm{S}+3\left[\mathrm{O}\right]\to {\mathrm{SO}}_3 \\ {\mathrm{SO}}_3+{\mathrm{H}}_2\mathrm{O}\to {\mathrm{H}}_2{\mathrm{SO}}_4 \end{gathered}$$

2. The result will be the formation of iodine, as shown below.

${\mathrm{HNO}}_3+\mathrm{KI}\to {\mathrm{KNO}}_3+{\mathrm{I}}_2+\mathrm{NO}+{\mathrm{H}}_2\mathrm{O}$

3. Nitric acid will dissolve in water to form hydronium ions and nitrate ions, as shown below.

${\mathrm{HNO}}_3+{\mathrm{H}}_2\mathrm{O}$ ⇌ ${\mathrm{H}}_3{\mathrm{O}}^{+}+{{\mathrm{NO}}_3}^{-}$

4. Nitric acid will react with sodium carbonate to form carbon dioxide, which upon passing through lime water will turn the lime water milky.

$$\begin{gathered} {\mathrm{NaCO}}_3+2{\mathrm{HNO}}_3\to 2{\mathrm{NaNO}}_3+{\mathrm{H}}_2\mathrm{O}+{\mathrm{CO}}_2 \\ \mathrm{Ca}{\left(\mathrm{OH}\right)}_2+{\mathrm{CO}}_2\to {\mathrm{CaCO}}_3+{\mathrm{H}}_2\mathrm{O} \end{gathered}$$

5. Nitric acid reacts with calcium carbonate to form calcium nitrate, carbon dioxide and water, as shown below.

${\mathrm{CaCO}}_3+2{\mathrm{HNO}}_3\to \mathrm{Ca}{\left({\mathrm{NO}}_3\right)}_2+{\mathrm{CO}}_2+{\mathrm{H}}_2\mathrm{O}$