Question

When sulphur reacts with conc. Sulphuric acid, it acts as a
A. Reducer
B. Oxidiser
C. Both of them
D. None of the above

Answer 1

Hint: When sulphur reacts with conc. Sulphuric acid releases electrons. The sulphur forms sulphur dioxide on reacting with conc. Sulphuric acid.

Complete step by step answer:
The reaction between sulphur and conc. Sulphuric acid is a redox reaction.
Redox reactions are the reactions in which oxidation and reduction both process take place. One species in redox reaction gets oxidised and another species gets reduced.
The reaction between sulphur and conc. Sulphuric acid is shown as follows:
${\text{S}}\,\,{\text{ + }}\,{\text{2}}\,{{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}\, \to \,2\,{\text{S}}{{\text{O}}_2}\, + \,{{\text{H}}_{\text{2}}}{\text{O}}$
The reaction between sulphur and conc. Sulphuric acid forms sulphur dioxide and water.
By the change in the oxidation state, the oxidised and reduced species or oxidiser or reducer can be determined.
The oxidation state of sulphur is zero and the oxidation state of sulphur is sulphur dioxide is + 4 so, sulphur releases electrons during the reaction.
The oxidation state of sulphur in conc. Sulphuric acid is + 6 and the oxidation state of sulphur in sulphur dioxide is + 4 so, sulphur of conc. Sulphuric acid accepts electrons during the reaction.
The sulphur gives electrons hence oxidised so, sulphur is known as reducing agent or reducer.
The conc. Sulphuric acid gains electrons released by the sulphur hence reduced so, conc. Sulphuric acid is known as oxidising agent or oxidiser.

So, the correct answer is “Option A”.

Note: Here, only the sulphur atom is oxidised and reduced during the reaction but this is not the disproportionation reaction because in disproportionation a single atom or molecule oxidised and reduced simultaneously. Here, the oxidised species is sulphur and reduced species is conc. sulphuric acid.