Question

Which one is known as the ‘Oil of Vitriol’?
(a) ${{H}_{2}}S{{O}_{3}}$
(b) ${{H}_{2}}S{{O}_{4}}$
(c) ${{H}_{2}}{{S}_{2}}{{O}_{7}}$
(d) None of these

Answer 1

Hint: Vitriol compounds are the ones which contain sulphate. Vitriol is another word for bitter criticism and malice which sounds acidic in nature/ in the sense of the word.

Complete Step by Step Solution:
Let us talk about the word ‘Oil of Vitriol’, a compound/acid or other is categorised in the Vitriol category if they contain Sulphate ($S{{O}_{4}}^{-2}$ ) group.
● In the given options, only Option B contains the sulphate group.
● Option B is also known as Sulphuric Acid. Also, colloquially sulphuric acid has had various names. Oil of Vitriol or Spirit of Vitriol is used till this day.
● The terminology Oil of Vitriol is given by the European alchemists as the sulphuric acid was synthesised using ‘green vitriol’ in an iron retort system. Green Vitriol is basically Hydrated Ferrous Sulphate ($FeS{{O}_{4}}.7{{H}_{2}}O$ ). This green vitriol was heated in order to extract the sulphuric acid.
● Option A as mentioned in the question is typically termed as Sulphurous Acid. It is a good reducing agent whereas the typical Sulphuric acid is a good oxidising agent.
● Option C is Disulphuric acid which is commonly known by the name of Oleum. It is a sulphur oxoacid. It is not a distinct molecule, it is actually a mixture of ${{H}_{2}}S{{O}_{4}}$ and $S{{O}_{3}}$ in 1:1 molar ratio.
● Therefore, it could be concluded that the Oil of Vitriol is ${{H}_{2}}S{{O}_{4}}$ (Option B).

Note: There are different types of Vitriol available. Oil of Vitriol or Spirit of Vitriol are termed (Sulphuric acid) because when the green vitriol was heated, it formed an oily form of solution which was an acid, which is today’s Sulphuric acid.