Question

Arrange the following acids in increasing order of their strength: HOF, HOCl, HBr, HI

Answer 1

HOCl, HOF, HBr, HI

Answer 2

1. For oxyacids (HOF and HOCl):

   • Acid strength often increases with the electronegativity of the halogen attached to –OH (when the number of oxygen atoms is the same).
   • Fluorine being more electronegative than chlorine, HOF is stronger than HOCl.

2. For binary hydrides (HBr and HI):

   • In the hydrogen halides, acid strength increases down the group due to increasing bond length and decreasing H–X bond strength.
   • Thus, HI is stronger than HBr.

3. Relative comparison:

   • Oxyacids (like HOF and HOCl) are generally much weaker than hydrohalic acids (HBr and HI).
   • Arranging from weakest to strongest: $$\text{HOCl} < \text{HOF} < \text{HBr} < \text{HI}$$

Core Explanation:

HOCl is the weakest oxyacid among the two (due to lesser electron withdrawal by Cl compared to F in HOF). Hydrohalic acids (HBr and HI) are very strong, with HI being the strongest due to the weakest H–I bond.