Salt Hydrolysis is the interaction of salt ions with water to produce either acidic or basic solutions. It is effectively the chemical opposite of a neutralization reaction.
The extent of this reaction is called the Degree of Hydrolysis ($h$), and the equilibrium constant is the Hydrolysis Constant ($K_h$).
Weak Acid & Strong Base Salt:
$$\text{pH} = 7 + \frac{1}{2}(pK_a + \log C)$$
Strong Acid & Weak Base Salt:
$$\text{pH} = 7 - \frac{1}{2}(pK_b + \log C)$$
1. Why is the pH of NaCl exactly 7.0?
Ions from strong acids and bases (like $Na^+$ and $Cl^-$) do not hydrolyze because they are extremely weak conjugate partners.
2. Does concentration affect Weak Acid + Weak Base salts?
No. The pH of WA/WB salts depends only on their respective $pK_a$ and $pK_b$ values, not the molarity.
3. What happens if I increase the temperature?
Since hydrolysis is endothermic, the degree of hydrolysis ($h$) increases, and the neutral point (usually 7.0) shifts downward slightly.