What is hydrolysis? Give the difference between non-hydrolyzing and hydrolyzing ions.

(N/A) Definition: The process of interaction between water and cations/anions or both of salts is called hydrolysis.
Salts formed by the reactions between acids and bases in definite proportions undergo ionization in water. The cations/anions formed on ionization of salts $(i)$ either exist as hydrated ions in aqueous solutions or $(ii)$ interact with water to reform corresponding acids/bases depending upon the nature of the salts. The $pH$ of the solution gets affected by this interaction.
$I$. Non-hydrolyzing ions (Hydrated but do not hydrolyze):
Such ions remain as ions in solution and do not affect the $pH$. They do not hydrolyze.
- Positive ions: Positive ions of strong bases ($Na^{+}$,$K^{+}$,$Ca^{2+}$,$Ba^{2+}$) exist as aqueous ions and are not hydrolyzed.
- Negative ions: Negative ions of strong acids ($Cl^{-}$,$Br^{-}$,$NO_{3}^{-}$,$ClO_{4}^{-}$,$SO_{4}^{2-}$) are not hydrolyzed.
Such solutions are neutral with $pH = 7$. e.g.,$NaCl$,$KCl$,$NaNO_{3}$,$NaClO_{4}$.
$II$. Hydrolyzing and interacting ions:
Such ions react with water according to the nature of the salt and the corresponding acid or base,affecting the $pH$. This process is known as hydrolysis.
- Positive ions: Salts of strong acids and weak bases (e.g.,$NH_{4}Cl$) contain cations like $NH_{4}^{+}$ which undergo hydrolysis,making the solution acidic.
- Negative ions: In solutions of weak acids and strong bases (e.g.,$NaCH_{3}COO$),the negative ion ($CH_{3}COO^{-}$,$HCOO^{-}$,$S^{2-}$,$CrO_{4}^{2-}$) undergoes hydrolysis,making the solution basic.
Such solutions are acidic or basic ($pH < 7$ or $pH > 7$). e.g.,$NH_{4}Cl$ (Acidic) and $CH_{3}COONa$ (Basic).
The formula for $pH$ is: $pH = 7 + \frac{1}{2} (pK_{a} - pK_{b})$.