Preparation of Acetate-Ammonium Acetate Buffer
It is a good idea to prepare acetate-ammonium acetate buffer. Acetate, a weak acid, is partially ionized in water, and its ionization equilibrium constant is\ (K_a\). Ammonium acetate, a strong electrolyte, is completely ionized into ammonium ions and acetate ions in water.

When preparing, the dosage of the two needs to be accurately calculated according to the pH value of the required buffer. According to the buffer solution pH calculation formula\ (pH = pK_a +\ lg\ frac {[conjugated base]} {[conjugated acid]}\), in this buffer system, acetic acid is a conjugated acid, and acetate ions (from ammonium acetate ionization) are conjugated bases.

If you want to match a buffer with a specific pH value, the value of acetic acid\ (pK_a\) is known, and you can substitute it into the formula to find the ratio of\ (\ frac {[acetate ion]} {[acetic acid]}\).

For example, if you want to match a buffer with a pH of\ (x\) and acetic acid is known\ (pK_a = y\), then\ (x = y +\ lg\ frac {[acetate ion]} {[acetic acid]}\), then calculate the value of\ (\ frac {[acetate ion]} {[acetic acid]}\).

Then, according to the total volume and concentration of the required buffer, calculate the amount of acetic acid and ammonium acetate. Suppose the total volume of the required buffer is\ (V\) L and the total concentration is\ (c\) mol/L. Let the amount of acetic acid be\ (n_1\) and the amount of ammonium acetate be\ (n_2\), according to the ratio calculated above by\ (\ frac {n_2} {n_1} =\), and\ (n_1 + n_2 = cV\), the simultaneous equations can be solved by\ (n_1\) and\ (n_2\).

After obtaining the amount of substance, if a commercially available solution of acetic acid (known at a concentration of\ (c_1\) mol/L) is prepared with ammonium acetate solids. Measure the volume of acetic acid solution\ (V_1 =\ frac {n_1} {c_1}\) mL, and weigh the solid mass of ammonium acetate\ (m = n_2M\) (\ (M\) is the molar mass of ammonium acetate) g.

The amount of acetic acid solution was injected into an appropriate amount of distilled water, and then weighed ammonium acetate solids were added, stirred to dissolve, to be completely dissolved, transferred to a volumetric flask, with distilled water bandwidth evaluation to\ (V\) L, shake, to obtain the desired acetate - ammonium acetate buffer.