Question

Sulphan is:
A. a mixture of $${\text{S}}{{\text{O}}_{\text{3}}}$$ and $${{\text{H}}_2}{\text{S}}{{\text{O}}_{\text{5}}}$$.
B. 100. conc. $${{\text{H}}_2}{\text{S}}{{\text{O}}_{\text{4}}}$$.
C. a mixture of gypsum and conc. $${{\text{H}}_2}{\text{S}}{{\text{O}}_{\text{4}}}$$.
D. 100% oleum (a mixture of 100% $${\text{S}}{{\text{O}}_{\text{3}}}$$ and 100% $${{\text{H}}_2}{\text{S}}{{\text{O}}_{\text{4}}}$$).

Answer 1

Hint: The other name of sulphan is oleum. The molecular formula of oleum is $${{\text{H}}_{\text{2}}}{{\text{S}}_{\text{2}}}{{\text{O}}_{\text{7}}}$$. From the molecular formula of oleum, the components which are involved in the mixture can be determined easily.

Complete step by step solution:
Sulphan is also referred to as oleum. The molecular formula of oleum is $${{\text{H}}_{\text{2}}}{{\text{S}}_{\text{2}}}{{\text{O}}_{\text{7}}}$$. It is made from mixture of 100% sulphuric acid $$\left( {{{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}} \right)$$ and 100% sulphur trioxide$$\left( {{\text{S}}{{\text{O}}_{\text{3}}}} \right)$$. The reaction is as follows:
$${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}} + {\text{S}}{{\text{O}}_{\text{3}}} \to {{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{7}}}\left( {{\text{oleum}}} \right)$$
Thus sulphan is 100% oleum which is made from 100% $${\text{S}}{{\text{O}}_{\text{3}}}$$ and 100% $${{\text{H}}_2}{\text{S}}{{\text{O}}_{\text{4}}}$$. Therefore, the correct option is D.

Additional Information: Sulphan is an extensively strong dehydrating agent (removal of water) which means it has the capability to remove all the water molecules from any compound. It is a thick corrosive substance. Sulphan is prepared through a contact process. Contact process is mainly utilized for the preparation of sulphuric acid $$\left( {{{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}} \right)$$.
The contact process includes the conversion of sulphur dioxide gas $$\left( {{\text{S}}{{\text{O}}_{\text{2}}}} \right)$$ into sulphur trioxide $$\left( {{\text{S}}{{\text{O}}_{\text{3}}}} \right)$$ in the availability of catalyst such as platinum or vanadium pentoxide $$\left( {{{\text{V}}_2}{{\text{O}}_5}} \right)$$. The sulphur trioxide formed is absorbed in concentrated sulphuric acid which leads to the formation of oleum. The reaction of oleum with water produces sulphuric acid.

Note: Sulphan is also known as 100% oleum. Remember the molecular formula of oleum that is $${{\text{H}}_{\text{2}}}{{\text{S}}_{\text{2}}}{{\text{O}}_{\text{7}}}$$. It is made from 100% conc. sulphuric acid saturated with 100% sulphur trioxide (excess).