Which one of the following orders correctly represents the increasing acid strengths of the given acids?
- HOClO < HOCl < HOClO3 < HOClO2
- HOClO3 < HOClO2 < HOClO < HOCl
- HOClO2 < HOClO3 < HOClO < HOCl
- HOCl < HOClO < HOClO2 < HOClO3
Answer
(4) HOCl < HOClO < HOClO2 < HOClO3
Solution
Oxidation state of Cl: HOCl (+1), HOClO (+3), HOClO2 (+5), HOClO3 (+7)
More O atoms on Cl pull electron density from the O–H bond and stabilise the conjugate anion by resonance
acid strength increases with the oxidation state of Cl.
HOCl < HOClO < HOClO2 < HOClO3
Answer: (4)