Answer
(a) The pH decreases.
(b) The pH increases.
(c) The pH stays the same.
Work Step by Step
(a)
Ammonium chloride: $N{H_4}Cl$;
- $N{H_4}^+$ is an acid, and $Cl^-$ doesn't affect the pH.
When you add an acid to a solution, its pH is going to decrease, because the solution will get more acidic.
(b)
Sodium acetate: $NaCH_3COO$;
- $Na^+$ doesn't affect the pH, and $CH_3COO^-$ is a base.
When you add a base to a solution, its pH is going to increase, because the solution will get more basic.
(c)
$Na^+$ doesn't affect the pH, and $Cl^-$ also doesn't.
Therefore, the pH will not change.
