Weak acid + Strong Base yields a basic salt; pH equivalence point is:

Weak acid + Strong Base yields a basic salt; pH equivalence point is:

• A. pH greater than 7
• B. pH less than 7
• C. pH equal to 7
• D. no defined pH

Answer: (A)

When a weak acid is titrated with a strong base, the equivalence point leaves you with the conjugate base of the weak acid in solution. This conjugate base, A-, hydrolyzes water to produce hydroxide ions: A- + H2O ⇌ HA + OH-. That extra OH- makes the solution basic, so the pH at the equivalence point is greater than 7. The exact value depends on the acid’s Ka and the concentration, but it will be above 7. This is why the correct description is a basic pH at equivalence.

When a weak acid is titrated with a strong base, the equivalence point leaves you with the conjugate base of the weak acid in solution. This conjugate base, A-, hydrolyzes water to produce hydroxide ions: A- + H2O ⇌ HA + OH-. That extra OH- makes the solution basic, so the pH at the equivalence point is greater than 7. The exact value depends on the acid’s Ka and the concentration, but it will be above 7. This is why the correct description is a basic pH at equivalence.