Discuss the physical and chemical properties of sulphuric acid.

(N/A) $(i)$ Physical properties: Sulphuric acid is a colourless,dense,oily liquid with a specific gravity of $1.84$ at $298 \ K$. The freezing point is $283 \ K$ and the boiling point is $611 \ K$. It dissolves in water with the evolution of a large quantity of heat. Hence,while diluting an acid,the acid must be added to water and not water to an acid with constant stirring.
$(ii)$ Chemical properties: The chemical reactions of sulphuric acid are a result of the following characteristics:
$(a)$ Low volatility
$(b)$ Strong acidic character
$(c)$ Strong affinity for water
$(d)$ Ability to act as an oxidising agent
In aqueous medium,sulphuric acid ionises in two steps:
$H_2SO_{4(aq)} + H_2O_{(l)} \rightarrow H_3O^{+}_{(aq)} + HSO^{-}_{4(aq)} ; Ka_1 = \text{very large } (Ka_1 > 10)$
$HSO^{-}_{4(aq)} + H_2O_{(l)} \rightarrow H_3O^{+}_{(aq)} + SO^{2-}_{4(aq)} ; Ka_2 = 1.2 \times 10^{-2}$
The larger value of $Ka_1$ $(Ka_1 > 10)$ means that $H_2SO_4$ is largely dissociated into $H^{+}$ and $HSO^{-}_4$. Greater the value of the dissociation constant $(K_a)$,the stronger is the acid. The acid forms two series of salts: Normal salts (e.g.,sodium sulphate,copper sulphate) and acid sulphates (e.g.,sodium hydrogen sulphate).
Sulphuric acid,because of its low volatility,can be used to manufacture more volatile acids from their corresponding salts:
$2MX + H_2SO_4 \rightarrow 2HX + M_2SO_4$ (where $X = F, Cl, NO_3$ and $M = \text{Metal}$).
Concentrated sulphuric acid is a strong dehydrating agent. Many wet gases can be dried by passing them through sulphuric acid,provided the gases do not react with the acid. Sulphuric acid removes water from organic compounds; it is evident by its charring action on carbohydrates:
$C_{12}H_{22}O_{11} \xrightarrow{H_2SO_4} 11H_2O + 12C$
Hot concentrated sulphuric acid is a moderately strong oxidising agent. It oxidises both metals and non-metals,being reduced to $SO_2$:
$Cu + 2H_2SO_4 \rightarrow CuSO_4 + SO_2 + 2H_2O$
$S + 2H_2SO_4 \rightarrow 3SO_2 + 2H_2O$
$C + 2H_2SO_4 \rightarrow CO_2 + 2SO_2 + 2H_2O$
Sulphuric acid is an important industrial chemical,often called the "King of chemicals".