Question

In the contact process, $S{O}_3$ is dissolved in concentrated Sulphuric acid to produce:

• A. Fuming Sulphuric acid
• B. Pyrosulphuric acid
• C. Oleum
• D. $H_2{S}_2{O}_7$

Answer 1

Answer: (A), (B), (C), (D)

$H_2{S}_2{O}_7$

$H_{2}S{O}_4\left(I\right)+S{O}_3\left(g\right)\to H_2{S}_2{O}_7\left(I\right)$

Oleum, the product on the right hand side is also knows as fuming sulphuric acid. It has other names – pyrosulphuric acid or disulphuric acid.

It has the following structure:

Each Sulphur atom is $s{p}^3$ hybridized as per VSEPR theory. Also, Sulphur retains its +6 oxidation much like in the case of the sulphate ion, Sulphuric acid and $S{O}_3$.