Question

Among the following the correct order of acidity is :

• A. ${HClO < HClO2 < HClO3 < HClO4 }$
• B. ${ HClO4 < HClO < HClO3 < HClO4}$
• C. ${ HClO4 < HClO2 < HClO < HClO3}$
• D. ${ HClO3 < HClO4 < HClO2 < HClO}$

Answer 1

The Correct Option is A

 The question involves determining the correct order of acidity among a series of oxoacids of chlorine: hypochlorous acid (\(HClO\)), chlorous acid (\(HClO_2\)), chloric acid (\(HClO_3\)), and perchloric acid (\(HClO_4\)). The acidity of oxoacids generally depends on the oxidation state of the central atom—in this case, chlorine.

**Explanation of Acidity in Chlorine Oxoacids**:

• The acidity of oxoacids increases with the increase in the oxidation state of the central atom. This is because higher oxidation states stabilize the conjugate base by dispersing negative charge through resonance and inductive effects, making the hydrogen ion more easily released.
• In this series, the oxidation states of chlorine in the acids are as follows:
  • \(HClO\) (hypochlorous acid): +1
  • \(HClO_2\) (chlorous acid): +3
  • \(HClO_3\) (chloric acid): +5
  • \(HClO_4\) (perchloric acid): +7

Since higher oxidation states correspond to stronger acids, the correct order of acidity from weakest to strongest is:

\(HClO < HClO_2 < HClO_3 < HClO_4\)

Therefore, the correct option given in the question matches this order:

Correct Answer: \(HClO < HClO_2 < HClO_3 < HClO_4\)

This trend follows due to the significant electron-withdrawing effect, which stabilizes the conjugate base as the oxidation number of chlorine increases, enhancing the acidic character.