Question

Among the following oxoacids, the correct decreasing order of acidic strength is

• A. $HOCl > HClO_2 > HClO_3 > HClO_4$
• B. $HClO_4 > HOCl > HClO_2 > HClO_3$
• C. $HClO_4 > HClO_3 > HClO_2 > HOCl$
• D. $HClO_2 > HClO_4 > HClO_3 > HOCl$

Answer 1

Answer: (C)

$HClO_4 > HClO_3 > HClO_2 > HOCl$

Answer 2

$HClO_4 {<=>} ClO^{-}_{4}+H^+$
$HClO_3 {<=>} ClO^{-}_3+H^+$
$HClO_2 {<=>}ClO^{-}_2+H^+$
$HOCl {<=>}ClO^{-}+H^{+}$

Resonance produced conjugate base

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(iv) $ClO^-$ is not resonance stabilized

As per resonance stability order of conjugate base is

$ClO _{4}^{-}> ClO _{3}^{-}> ClO _{2}^{-}> ClO ^{-}$

Hence acidic strength order is

$HClO _{4}> HClO _{3}> HClO _{2}> HClO$