Differentiating Acidic And Basic Salts
Salt solutions can be acidic, neutral, or basic. Let's consider a salt solution of NaF. NaF dissolves in water to form sodium and fluoride ions.
While the sodium ion is not reactive to water, the fluoride ion is reactive to water (fluoride is the conjugate base of a weak acid, HF). The fluoride ion can act as a base by accepting a proton from H2O by the process of hydrolysis. The reaction is shown below.
The increased presence of hydroxide ions (notice the formation of hydroxide ions as one of products of the hydrolysis reaction) makes the solution basic. This strategy can be used to predict whether a salt solution is acidic, basic, or neutral.
- A salt of a strong base and a strong acid gives a neutral aqueous solution.
Eg: NaCl is a salt of a strong acid (HCl) and a strong base (NaOH).
- A salt of a weak acid and a strong base gives a basic aqueous solution.
- A salt of a weak base and a strong acid gives an acidic aqueous solution.