Answer

Sulphuric acid is an important industrial chemicaland is used for a lot of purposes. Some important uses of sulphuric acid are given below.

(i) It is used in fertilizer industry. It is used to make various fertilizers such as ammonium sulphate and calcium super phosphate.

(ii) It is used in the manufacture of pigments, paints, and detergents.

(iii) It is used in the manufacture of storage batteries.

Answer

Manufacture of sulphuric acid by Contact process involves three steps.

1. Burning of ores to form $\mathrm{SO_2}$

2. Conversion of $\mathrm{SO_2}$ to $\mathrm{SO_3}$ by the reaction of the former with $\mathrm{O_2}$

$\left(\mathrm{V_2} \mathrm{O_5}\right.$ is used in this process as a catalyst.)

3. Absorption of $\mathrm{SO_3}$ in $\mathrm{H_2} \mathrm{SO_4}$ to give oleum $\left(\mathrm{H_2} \mathrm{~S_2} \mathrm{O_7}\right)$

The key step in this process is the second step. In this step, two moles of gaseous reactants combine to give one mole of gaseous product. Also, this reaction is exothermic. Thus, in accordance with Le Chatelier’s principle, to obtain the maximum amount of $\mathrm{SO_3}$ gas, temperature should be low and pressure should be high.

Answer

$$ \begin{aligned} & \mathrm{H_2} \mathrm{SO_4(a q)}+\mathrm{H_2} \mathrm{O_(l)} \longrightarrow \mathrm{H_3} \mathrm{O_(a q)}^{+}+\mathrm{HSO_4(a q)}^{-} ; \quad K_{a_{1}}>10 \\ & \mathrm{HSO_4(a q)}^{-}+\mathrm{H_2} \mathrm{O_(l)} \longrightarrow \mathrm{H_3} \mathrm{O_(a q)}^{+}+\mathrm{SO_4(a q)}^{-} ; \quad K_{a_{2}}=1.2 \times 10^{-2} \\ & \text { It can be noticed that } K_{a_{1}} > > K_{a_{2}} \end{aligned} $$

This is because a neutral $\mathrm{H_2} \mathrm{SO_4}$ has a much higher tendency to lose a proton than the negatively charged $\mathrm{HSO_4}^{-}$. Thus, the former is a much stronger acid than the latter.