On the pH value of ammonium acetate buffer Ammonium acetate buffer has important uses in many fields of chemical experiments. The precise regulation of its pH value is related to the success or failure of many experiments.

To obtain an ideal pH value of ammonium acetate buffer, the preparation process must be cautious. Ammonium acetate is a salt obtained by neutralizing acetic acid and ammonia. In solution, acetate ions and ammonium ions undergo hydrolysis.

Acetate ion hydrolysis makes the solution alkaline: $CH_3COO ^ - + H_2O\ rightleftharpoons CH_3COOH + OH ^ - $; ammonium ion hydrolysis makes the solution acidic: $NH_4 ^ ++ H_2O\ rightleftharpoons NH_3 · H_2O + H ^ + $.

The degree of hydrolysis of the two affects each other. When the degree of hydrolysis of the two is similar, the pH value of the solution is about 7. However, in actual operation, due to the interference of temperature, concentration and other factors, the pH value often needs to be fine-tuned.

Adjust the pH value of ammonium acetate buffer, the common method is to add an appropriate amount of acetic acid or ammonia water. If the pH value is too high, a little acetic acid can be added dropwise to promote the balance to move in the direction of generating ammonium acetate, reducing the concentration of $OH ^ - $, thereby reducing the pH value; if the pH value is too low, a small amount of ammonia water can be added to increase the concentration of $OH ^ - $, and increase the pH value.

Accurate pH determination is also essential, and pH meters are commonly used for measurement. Before measurement, the pH meter needs to be accurately calibrated to ensure the accuracy of the measurement data.

In addition, storage conditions also affect the pH value of ammonium acetate buffer. Temperature changes will change the hydrolysis equilibrium constant, causing pH fluctuations. Therefore, the buffer should be stored in a suitable temperature environment.

In short, in-depth understanding of the pH-related characteristics of ammonium acetate buffer, proficiency in its adjustment and determination methods, and proper control of storage conditions can effectively use ammonium acetate buffer in the experiment, laying a solid foundation for the success of the experiment.