Question

The catalyst used in making ${\mathrm{H}}_2{\mathrm{SO}}_4$ in contact process is

Answer 1

Contact process:-

• The contact process is one of the most common methods of forming Sulphuric acid$\left({\mathrm{H}}_2{\mathrm{SO}}_4\right)$.
• In this process not only Sulphuric acid is formed, but Oleum$\left({\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_7\right)$ and Sulphur trioxide$\left({\mathrm{SO}}_3\right)$ is also formed.

Step 1: Formation of Sulphur trioxide

First, Sulphur dioxide and oxygen are combined in a $1:1$ratio.

And it is then treated with the catalyst Vanadium pentoxide$\left({\mathrm{V}}_2{\mathrm{O}}_5\right)$at a temperature between $\left(400-450\right)°\mathrm{C}$and $1-2\mathrm{atm}$pressure.

This converts the Sulphur dioxide into Sulphur trioxide:

$\underset{\mathrm{Sulphur}\mathrm{dioxide}}{2{\mathrm{SO}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}\underset{1-2\mathrm{atm}}{\overset{{\mathrm{V}}_2{\mathrm{O}}_5,(400-450)°\mathrm{C}}{\to }}\underset{\mathrm{Sulphur}\mathrm{trioxide}}{2{\mathrm{SO}}_3\left(\mathrm{g}\right)}$

Step 2: Formation of Sulphuric acid

Now this Sulphur trioxide formed is reacted with Sulphuric acid in order to dilute it.

in this process Oleum$\left({\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_7\right)$ is formed:

$\underset{\mathrm{Sulphur}\mathrm{trioxide}}{{\mathrm{SO}}_3\left(\mathrm{g}\right)}+\underset{\mathrm{Sulphuric}\mathrm{acid}}{{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)}\to \underset{\mathrm{Oleum}}{{\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_7\left(\mathrm{aq}\right)}$

This Oleum formed is then diluted with water to ultimately yield Sulphuric acid:

$\underset{\mathrm{Oleum}}{{\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_7\left(\mathrm{aq}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\mathrm{Sulphuric}\mathrm{acid}}{{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)}$

Therefore, the catalyst used in making ${\mathrm{H}}_2{\mathrm{SO}}_4$ in contact process is Vanadium pentoxide$\left({\mathrm{V}}_2{\mathrm{O}}_5\right)$.