Question

Why strength of oxyacids decrease with increase in size?

Answer 1

· With oxoacids containing the same number of Oxygen atoms, but different central atoms, acid strength increases as the electronegativity of the central atom increases. ... As electronegativity (of the central atom) increases, electron density of the O—H bond decreases, and the bond ...

Answer 2

Acid strength decreases as X moves down a group due to the increasing size of X. (H-X bond gets weaker and X- becomes more stable.) This effect of size outweighs the effect of decreasing electronegativity because of the large change in size.