On the pH of ammonium acetate solution

To know the pH of ammonium acetate solution, it is necessary to investigate its properties. Ammonium acetate is a salt of acetate ion and ammonium ion.

Acetate ion, with hydrolytic properties, can be combined with hydrogen ions in water to make the solution alkaline. The hydrolysis formula is: $CH_ {3} COO ^{-} + H_ {2} O\ rightleftharpoons CH_ {3} COOH + OH ^ {-} $.

Ammonium ions can also be hydrolyzed, and they combine with hydroxide ions in water, making the solution acidic. The hydrolysis formula is: $NH_ {4 }^{+} + H_ {2} O\ rightleftharpoons NH_ {3}\ cdot H_ {2} O + H ^{+}$。

To break the pH of ammonium acetate solution, it is necessary to compare the degree of hydrolysis of acetate ion and ammonium ion. The ionization constant of acetic acid is similar to that of ammonia monohydrate, so the degree of hydrolysis of acetate ion and ammonium ion is also similar. It can be seen that ammonium acetate solution is almost neutral, and its pH is about 7.

However, in practice, many factors can affect its hydrolysis equilibrium, such as temperature and concentration. When the temperature rises, the hydrolysis equilibrium shifts to the right, which has a slight impact on the pH of the solution; when the concentration changes, the degree of hydrolysis will also change, which in turn will change the pH. But in general, under normal circumstances, the pH of ammonium acetate solution is roughly 7.