Question

Explain why HI is more acidic than HCl but HOI is less acidic than HOCl?

Answer 1

Answer

A binary acid's strength depend upon the H-X bond strength, weaker the bond stronger the acid. The HI is more acidic than HCl because I is bigger in size compare to Cl.The H-I bond is weaker than H-Cl bond and hence proton more easily remove from H-I.

Whereas in oxyacids the acid strength depend upon the electronegativity of central atom and number of oxygen atoms. The HOCl is more acidic than HOI because Cl is more electronegative than I. The more the electronegative halogen, more tendency to pull electrons and weaker the O-H bond hence proton more easily remove.