Question

Assign appropriate reasons for the following statement: Perchloric acid is a stronger acid than sulphuric acid.

Answer 1

Hint : We know that perchloric acid is the strongest acid with molecular formula, $Cl{{O}_{3}}\left( OH \right).$ Compared to all the given choices, perchloric acid shows the highest oxidation number on chlorine or the central atom.

Complete Step By Step Answer:
When we say a strong acid, we refer to its tendency to lose hydrogen readily. Now when the central atom, and in the above examples have different oxidation states, the readiness of the hydrogen atom to break from the molecule depends on the positivity of the oxidation number of the central atom. $S{{O}_{2}}{{\left( OH \right)}_{2}}$ is the most popular sulphuric acid and the oxidation number of sulphur is $+6.$ In $Cl{{O}_{2}}\left( OH \right)$ , the oxidation number of chlorine is $+5$ and in case of $Cl{{O}_{3}}\left( OH \right)$ the oxidation number of chlorine is $+7.$ Thus the bond that is the weakest in perchloric acid is $Cl{{O}_{3}}\left( OH \right)$ and thus it is our answer to the strongest acid. It is stronger than the most popular nitric acid also. The oxidation state of $Cl$ in perchloric acid is $+7$ while that of $S$ in sulphuric acid is $+6.$ Greater the oxidation state of the central atom, more readily the $O-H$ bond breaks and hence stronger is the acid.

Note :
Remember that the perchloric acid is considered to be highly corrosive in nature and it is useful in rocketry for its potentially explosive mixtures. We can also say that there are three atoms of oxygen and these will attract the electrons of oxygen hydrogen towards oxygen and make the bond weaker.