Question

(a) Describe one experiment to show that concentrated Sulphuric acid can remove hydrogen and oxygen in the ratio of 2:1 to form water.

(b) Describe two reactions in which Sulphuric acid behaves as an acid.

Answer 1

(a)

Dehydration of Sugar:

1. Concentrated Sulphuric acid $\left({\mathrm{H}}_2{\mathrm{SO}}_4\right)$ reacts rapidly with sugar $\left({\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6\right)$ to produce carbon $\left(\mathrm{C}\right)$ and water$\left({\mathrm{H}}_2\mathrm{O}\right)$.
2. When concentrated Sulphuric acid is poured on sugar crystals in the vessel, it produces a lot of heat in the surroundings. Therefore, this is known as an exothermic reaction.
3. This results in the formation of black-colored spongy carbon $\left(\mathrm{C}\right)$ which covers the reaction vessel and water vapor$\left({\mathrm{H}}_2\mathrm{O}\right)$.
4. This mixture is very hot due to its exothermic nature.
5. The hydrogen and oxygen are eliminated from sugar in the stoichiometric ratio of 2:1 to produce water.
6. The reaction takes place according to the following balanced chemical equation:
   ${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6\left(\mathrm{aq}\right)\stackrel{\mathrm{Conc}. {\mathrm{H}}_2{\mathrm{SO}}_4}{\to }6\mathrm{C}\left(\mathrm{s}\right)+6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

(b)

Reaction with sodium hydroxide:

1. Sodium hydroxide $\left(\mathrm{NaOH}\right)$ is a strong base.
2. Sulphuric acid $\left({\mathrm{H}}_2{\mathrm{SO}}_4\right)$ is a strong acid.
3. When Sodium hydroxide reacts with Sulphuric acid to form Sodium sulphate $\left({\mathrm{Na}}_2{\mathrm{SO}}_4\right)$ salt and water $\left({\mathrm{H}}_2\mathrm{O}\right)$.
4. This reaction takes place according to the following balanced chemical equation:
   ${\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)+2\mathrm{NaOH}\left(\mathrm{aq}\right)\to {\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$
5. In this reaction, Sulphuric acid behaves as an acid.

Reaction with magnesium oxide:

1. Magnesium oxide $\left(\mathrm{MgO}\right)$ is a base.
2. Sulphuric acid $\left({\mathrm{H}}_2{\mathrm{SO}}_4\right)$ is a strong acid.
3. When Magnesium oxide combines chemically with Sulphuric acid to give Magnesium sulphate $\left({\mathrm{MgSO}}_4\right)$ and water$\left({\mathrm{H}}_2\mathrm{O}\right)$.
4. The reaction takes place according to the following balanced chemical equation:
   $\mathrm{MgO}\left(\mathrm{s}\right)+{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)\to {\mathrm{MgSO}}_4\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$
5. In this reaction, Sulphuric acid acts as an acid, and Magnesium oxide is a base.