Which salt will yield a basic solution when dissolved in water?

Which salt will yield a basic solution when dissolved in water?

• A. Salt derived from strong base and weak acid
• B. Salt derived from weak base and strong acid
• C. Salt derived from strong acid and strong base
• D. Salt derived from weak acid and weak base

Answer: (A)

Salts affect water pH through hydrolysis, which depends on whether each ion is the conjugate acid or conjugate base of a weak species. The ion from a strong base tends to be neutral in water, while the ion from a weak acid can act as a base by accepting a proton from water. When a salt is made from a strong base and a weak acid, the cation (from the strong base) doesn’t hydrolyze appreciably and is effectively neutral, but the anion is the conjugate base of a weak acid and will hydrolyze: A− + H2O ⇌ HA + OH−. This production of hydroxide ions makes the solution basic. In contrast, a salt formed from a weak base and a strong acid has a cation that can donate protons to water (acidic tendency) while the anion from the strong acid is neutral, leading to an overall acidic solution. Salts from strong acid and strong base are essentially neutral because neither ion hydrolyzes, and salts from weak acid and weak base can lean acidic or basic depending on the relative strengths, often giving a pH near 7 but not predictably. So a salt derived from a strong base and a weak acid yields a basic solution, with an example being sodium acetate.

Salts affect water pH through hydrolysis, which depends on whether each ion is the conjugate acid or conjugate base of a weak species. The ion from a strong base tends to be neutral in water, while the ion from a weak acid can act as a base by accepting a proton from water. When a salt is made from a strong base and a weak acid, the cation (from the strong base) doesn’t hydrolyze appreciably and is effectively neutral, but the anion is the conjugate base of a weak acid and will hydrolyze: A− + H2O ⇌ HA + OH−. This production of hydroxide ions makes the solution basic. In contrast, a salt formed from a weak base and a strong acid has a cation that can donate protons to water (acidic tendency) while the anion from the strong acid is neutral, leading to an overall acidic solution. Salts from strong acid and strong base are essentially neutral because neither ion hydrolyzes, and salts from weak acid and weak base can lean acidic or basic depending on the relative strengths, often giving a pH near 7 but not predictably. So a salt derived from a strong base and a weak acid yields a basic solution, with an example being sodium acetate.