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Which one of the following orders correctly represents the increasing acid strengths of the given acids?
A
$HOClO \lt HOCl \lt HOClO_3 \lt HOClO_2$
B
$HOClO_2 \lt HOClO_3 \lt HOClO \lt HOCl$
C
$HOClO_3 \lt HOClO_2 \lt HOClO \lt HOCl$
D
$HOCl \lt HOClO \lt HOClO_2 \lt HOClO_3$
Detailed Solution
Oxidation numbers of chlorine: $HOCl$ (+1), $HOClO$ (+3), $HOClO_2$ (+5), $HOClO_3$ (+7).
As the oxidation number of the central atom increases, the strength of the oxoacid also increases.
More oxygen atoms on chlorine pull electron density away from the O-H bond, so the proton is released more easily.
Also, the negative charge of the conjugate base is delocalised over more oxygen atoms: $ClO^- \lt ClO_2^- \lt ClO_3^- \lt ClO_4^-$ in stability.
A more stable conjugate base means a stronger acid.
Increasing acid strength: $HOCl \lt HOClO \lt HOClO_2 \lt HOClO_3$
As the oxidation number of the central atom increases, the strength of the oxoacid also increases.
More oxygen atoms on chlorine pull electron density away from the O-H bond, so the proton is released more easily.
Also, the negative charge of the conjugate base is delocalised over more oxygen atoms: $ClO^- \lt ClO_2^- \lt ClO_3^- \lt ClO_4^-$ in stability.
A more stable conjugate base means a stronger acid.
Increasing acid strength: $HOCl \lt HOClO \lt HOClO_2 \lt HOClO_3$