Question

(c) (i) Name the process used for the large scale manufacture of sulphuric acid.
(ii) Which property of sulphuric acid accounts for its use as a dehydrating agent?
(iii) Concentrated sulphuric acid is both an oxidizing agent and non-volatile acid. Write one equation each to illustrate the above mentioned properties of sulphuric acid.

Answer 1

(i) The contact process is widely used for commercial production of sulphuric acid.
(ii) The strong affinity of sulphuric acid for water accounts for its use as a dehydrating agent.

(iii) Concentrated sulphuric acid is a strong oxidising agent. It oxidises metals as well as non-metals. Any one of the following reaction can be used to illustrate the oxidising nature of sulphuric acid:

Reaction with non-metals: Non-metals are oxidised to corresponding oxides on reaction with concentrated sulphuric acid. For example, consider the following reactions:

C + 2H₂SO₄ → CO₂ + 2SO₂ + 2H₂O
S + 2H₂SO₄ → 3SO₂ + 2H₂O

(iii) The non-volatile nature of sulphuric acid is depicted through its use in preparing volatile acids like HCl and HNO_3. The equations for the reactions are as follows:

$\text{K}{\mathrm{NO}}_3+{\mathrm{H}}_2{\mathrm{SO}}_4\stackrel{<200°\mathrm{C}}{\to }\text{K}{\mathrm{HSO}}_4+{\mathrm{HNO}}_3$
$\mathrm{NaCl}+{\mathrm{H}}_2{\mathrm{SO}}_4\stackrel{200°\mathrm{C}}{\to }{\mathrm{NaHSO}}_4+\mathrm{HCl}$