Question

Sulphuric acid is used to prepare a number of gases in the laboratory. Write balanced equations for the reactions in which the following gases are obtained by using dilute sulphuric acid as one of the reactants:

(a) Hydrogen

(b) Carbon dioxide

(c) Sulphur dioxide

Answer 1

(a)

Reaction between dilute Sulphuric acid and active metals:

1. In the laboratory, dilute Sulphuric acid is used to prepare hydrogen gas because it acts as a source of hydrogen.
2. Dilute Sulphuric acid reacts with active metals to produce hydrogen gas and the corresponding metal salts.
3. For example, Iron $\left(\mathrm{Fe}\right)$ metal can react with dilute Sulphuric acid $\left( {\mathrm{H}}_2{\mathrm{SO}}_4\right)$ to produce hydrogen $\left({\mathrm{H}}_2\right)$ gas and Ferrous sulphate $\left({\mathrm{FeSO}}_4\right)$ salt.
4. The balanced chemical equation for the reaction between iron metal and dilute Sulphuric acid is written as follows:
   $\mathrm{Fe}\left(\mathrm{s}\right)+\mathrm{dil}. {\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\to {\mathrm{FeSO}}_4\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)$

(b)

Reaction between dilute Sulphuric acid and metal carbonates or metal bicarbonates:

1. Dilute Sulphuric acid is used to prepare carbon dioxide gas in the chemistry laboratory.
2. When metal carbonates or metal bicarbonates is treated with dilute sulphuric acid, it releases carbon dioxide gas, water and the corresponding metal sulphate salts.
3. For example, Magnesium carbonate $\left({\mathrm{MgCO}}_3\right)$ treats with dilute Sulphuric acid $\left( {\mathrm{H}}_2{\mathrm{SO}}_4\right)$ to give Magnesium sulphate $\left({\mathrm{MgSO}}_4\right)$, water $\left({\mathrm{H}}_2\mathrm{O}\right)$ and carbon dioxide $\left({\mathrm{CO}}_2\right)$ gas.
4. The balanced chemical equation for the reaction between Magnesium carbonate and dilute Sulphuric acid is written as follows:${\mathrm{MgCO}}_3\left(\mathrm{s}\right)+\mathrm{dil}. {\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\to {\mathrm{MgSO}}_4\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)$

(c)

Reaction between dilute Sulphuric acid and metal sulphites or metal bisulphites:

1. Dilute Sulphuric acid is used to prepare sulphur dioxide gas in the chemistry laboratory.
2. When metal sulphites or metal bisulphites is treated with dilute Sulphuric acid, it gives Sulphur dioxide gas, water and their metal sulphate salts.
3. For example, Sodium sulphites $\left({\mathrm{Na}}_2{\mathrm{SO}}_3\right)$ reacts with dilute Sulphuric acid $\left( {\mathrm{H}}_2{\mathrm{SO}}_4\right)$ to give sodium sulphate $\left({\mathrm{Na}}_2{\mathrm{SO}}_4\right)$ and water$\left({\mathrm{H}}_2\mathrm{O}\right)$, evolving Sulphur dioxide $\left({\mathrm{SO}}_2\right)$ gas.
4. The balanced chemical equation for the reaction between Sodium sulphites and dilute Sulphuric acid is written as follows:
   ${\mathrm{Na}}_2{\mathrm{SO}}_3\left(\mathrm{s}\right)+\mathrm{dil}. {\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\to {\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+{\mathrm{SO}}_2\left(\mathrm{g}\right)$