Salt Hydrolysis

Simple Explanation

Salt hydrolysis is the reaction of a salt's ions with water, which can make the resulting solution acidic, basic, or neutral — depending on whether the salt came from a strong or weak acid and a strong or weak base.

Why Do We Need It?

This explains a fact that often surprises students: dissolving a 'neutral-looking' salt like sodium acetate in water actually produces a BASIC solution, not a neutral one — salts are not automatically pH-neutral just because they are neither an acid nor a base themselves.

Why Does This Work?

When a salt formed from a weak acid dissolves, its anion (the conjugate base of that weak acid) is itself a reasonably strong base — it reacts with water to generate OH⁻, making the solution basic. Similarly, a salt formed from a weak base has a cation (the conjugate acid) that reacts with water to generate H⁺, making the solution acidic. A salt from a strong acid AND a strong base has ions too weak to react with water at all, giving a neutral solution.

Real-Life Example

Practice

Quick Review

• ✓Salt hydrolysis: a salt's ions can react with water, affecting solution pH.
• ✓Weak acid + strong base salt → basic solution (e.g. sodium acetate).
• ✓Weak base + strong acid salt → acidic solution (e.g. ammonium chloride).