Question

Which is weakest `H-X` bond for the series `HI`, `HBr`, `HCl`, and `HF`?

Answer 1

There is a single covalent bond between hydrogen and the halogen. `H-I` is both longer and weaker.

Explanation:

In the gaseous phase, both hydrogen halides, `HCl` and `HI`, exist.

In aqueous solution, what do you think happens almost completely?

`HX(g) + H_2O rarr H_3O^(+) + X^(-)(aq)`

When you open a bottle of concentrated acid, you often get a nasty whiff of the acid!

Hydrochloric, hydrobromic, and hydroiodic acids are all strong acids in water. On the other hand, hydrofluoric acid, is classified as a weak acid in water. Why? (It has to do with hydrogen-halogen bond strength and overlap.)