Ammonium Acetate Buffer Recipe
1. Required Materials
1. ** Acetic Acid (CH 😉 COOH) **: Analytical Purity Grade, used to provide the acidic component.
2. ** Ammonium Acetate (CH 😉 COONH) **: Analytical Purity Grade, used as the salt component in the buffer system.
3. ** Distilled Water **: used to dissolve the solute, to prepare the buffer.

Second, the preparation method of buffers with different pH values
1. ** pH 4.5 Ammonium acetate buffer **
- ** Calculation **: According to the buffer solution pH calculation formula\ (pH = pKa +\ lg\ frac {[salt]} {[acid]}\), acetic acid\ (pKa = 4.76\). Let\ (n_ {salt}\) be the amount of ammonium acetate,\ (n_ {acid}\) be the amount of acetic acid, when\ (pH = 4.5\),\ (4.5 = 4.76 +\ lg\ frac {n_ {salt}} {n_ {acid}}\), you can get\ (\ lg\ frac {n_ {salt}} {n_ {acid}} = -0.26\), that is,\ (\ frac {n_ {salt}} {n_ {acid}}\ approx0.55\).
- ** Operation **: If the buffer of\ (1L 0.1mol/L\) is prepared, ammonium acetate\ (x mol\), acetic acid\ (y mol\), and\ (x + y = 0.1\),\ (\ frac {x} {y} = 0.55\), the solution is\ (x\ approx0.035mol\),\ (y\ approx0.065mol\). Accurately weigh ammonium acetate about\ (2.78g\) (\ (M_ {ammonium acetate} = 77.08g/mol\),\ (m = nM = 0.035mol × 77.08g/mol\ approx2.78g\)), measure glacial acetic acid about\ (3.84mL\) (\ (M_ {acetic acid} = 60.05g/mol\),\ (\ rho = 1.05g/mL\),\ (V =\ frac {m} {\ rho} =\ frac {0.065mol × 60.05g/mol} {1.05g/mL}\ approx3.84mL\)), placed in a\ (1L\) volumetric flask, add distilled water bandwidth evaluation to the scale line, shake well.
2. ** pH 5.0 Ammonium Acetate Buffer **
- ** Calculation **: Also according to the above formula, when\ (pH = 5.0\),\ (5.0 = 4.76 +\ lg\ frac {n_ {salt}} {n_ {acid}}\), you can get\ (\ lg\ frac {n_ {salt}} {n_ {acid}} = 0.24\), that is\ (\ frac {n_ {salt}} {n_ {acid}}\ approx1.74\).
- ** Operation **: If the buffer of\ (1L 0.1mol/L\) is prepared, ammonium acetate\ (a mol\), acetic acid\ (b mol\), and\ (a + b = 0.1\),\ (\ frac {a} {b} = 1.74\), the solution is\ (a\ approx0.064mol\),\ (b\ approx0.036mol\). Accurately weigh ammonium acetate about\ (4.93g\) (\ (m = nM = 0.064mol × 77.08g/mol\ approx4.93g\)), measure glacial acetic acid about\ (2.09mL\) (\ (V =\ frac {m} {\ rho} =\ frac {0.036mol × 60.05g/mol} {1.05g/mL}\ approx2.09mL\)), placed in a\ (1L\) volumetric flask, add distilled water bandwidth evaluation to the scale line, shake well.

3. Precautions
1. The purity of acetic acid and ammonium acetate used should be guaranteed, and the reagents should be checked for deterioration before use.
2. When measuring acetic acid, due to its volatility and irritation, it should be operated in a fume hood and pay attention to protection.
3.Bandwidth evaluation should be accurate. If the liquid level is found to be lower than the scale line after shaking the solution, no more water should be added, because the solution adheres to the inner wall of the volumetric bottle and causes the liquid level to change. It is a normal phenomenon.