Question

Looking at an ion, how can you tell whether hydrolysis will occur or not?

Answer 1

Cations of weak bases and Anions of weak acids are hydrolysed

Explanation:

If the ion is a cation that forms an weak base combining with required number of `OH^-`ion/s in water then the its solution becomes acidic one due to hydrolysis. For example `Fe^(3+)` ion

`Fe^(3+)+3H_2O->Fe(OH)_3+3H^+`

Again when an anion of a salt of weak acid interacts with water it combines with the `H^+`ions of water thereby enhancing the number of `OH^-` ions in water and thus it makes the solution basic in nature.
For example Acetate ion `CH_3COO^(-)`

`CH_3COO^(-)+H_2O->CH_3COOH+OH^-`

Inference

Cations of weak bases and Anions of weak acids are hydrolysed