Question

How can you predict if an ionic compound will have a further hydrolysis reaction? (what needs to be true of at least one of its ions?)

Answer 1

1. The salt of weak and strong acid/base have some residual property of strong acid/base.

2. You need to calculate its hydrolysis constant, if it has some appreciable value then hydrolysis will occur else not

For example

CH₃COOH + NaOH -----> CH₃COONa + H₂O

here CH₃COONa is salt of strong base and weak acid and it has residual property of base and hence it will hydrolyse

K_a of CH₃COOH = 1.8 x 18^-5

hydrolysis constant K_h = K_w/K_a = 10^-14/1.8 x 10^-5 = 5.55 x 10^-10

If you see salt of HCl and NaOH both are strong and its salt won't hydrolyse

If you calculate its Kh it will be very - very less than 1 , of the order of 10^-30 and hence not much appreciable hydrolysis