Name: Allotropes of Sulphur
Uploaded: 2019-07-19
Duration: 6 min 39 s
Description: Sulphur is one of the most useful non-metals which has wide applications in our industries. Watch this video to learn about the important allotropes of sulphur.

Question

Describe the manufacture of

H_{2} {SO}_{4}

by contact process?

Accepted Answer

Sulphuric acid is manufactured on a large scale by the contact process. It involves the following three steps:
Step (I): Sulphur or sulphide ores are burnt in air to form ${SO}_{2}$ .
Step (II): ${SO}_{2}$ is converted into ${SO}_{3}$ in the presence of $V_{2} O_{5}$ as a catalyst.

$2 {SO}_{2} (g) + O_{2} (g) \overset{V_{2} O_{5}}{\to} 2 {SO}_{3} (g) ∆_{t} H ° = - 196.6 {kJmol}^{- 1}$
Step (III): ${SO}_{3}$ produced in the above step is absorbed on $H_{2} {SO}_{4}$ to give $H_{2} S_{2} O_{7}$ (Oleum). This oleum is then diluted to obtain $H_{2} {SO}_{4}$ of the desired concentration.

$H_{2} {SO}_{4}$

The second step is the key step. It is very crucial to maximise the yield of $H_{2} {SO}_{4}$ .
The above reaction is exothermic, reversible, and the forward reaction leads to a decrease in volume. So, in accordance with Le Chatelier's principle, low temperature and high pressure are the favourable conditions for maximum yield. But the temperature should not be too low since the rate of reaction will become slow.
The optimum conditions in the contact process to maximise the yield of sulphuric acid in an industrial plant is a pressure of $2$ bar and temperature around $720 K$ .

Describe the manufacture of $H_{2} {SO}_{4}$ by contact process?

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Describe the manufacture of H2SO4 by contact process?