Question

Identify the correct decreasing order of acid strength for the following compounds:

$\text{(I)}\text{HClO,}\text{(II)}\text{HBrO,}\text{(III)}\text{HIO}$

• A. I > II > III
• B. II > I > III
• C. III > II > I
• D. I > III > II

Answer 1

Answer: (A)

The acidic character of hypohalous acid depends on the electronegativity of halogen. As the electronegativity value of halogen increases the acidic strength of hypohalous acid increases.

Here, Electronegativity of atom $\text{X}$ ( $\text{Cl,}\text{Br}$ or $\text{I}$ ) attached to $\text{O}$ decreases down the group, polarity of OH bond decreases, acid strength decreases. It means more the electronegativity of the halogen atom, more the tendency to pull electron and weaker the $\text{O}-\text{H}$ bond and hence proton ${\left(\text{(H}\right)}^{\text{+}}\text{)}$ can easily be removed.