fect of concentration of buffer H2PO4- + H2O ======== HPO4^-2 + H3O+ CASE1. Using 0.1 M phosphate buffer, pH 7.2, prepare 25mL each of the buffer solutions with the following concentrations at pH 7.2: 1. 0.005 M 2. 0.05 M 3. 0.10 M
1. Effect of concentration of buffer
H2PO4- + H2O ======== HPO4^-2 + H3O+
CASE1. Using 0.1 M phosphate buffer, pH 7.2, prepare 25mL each of the buffer solutions with the following concentrations at pH 7.2:
1. 0.005 M
2. 0.05 M
3. 0.10 M
CASE 2. Using 0.1 M acetate buffer, pH 4.7, prepare 25 mL each of the buffer solutions with the following concentrations at pH 4.7:
Record the pH of each of the buffer solutions. Add 2 mL of 0.1 M NaOH to each of the 25 mL buffer samples assigned to your group. Record the pH of each buffer solution after the addition of alkali. Account for the magnitude of the change in pH.
2. Effect of the ratio of the conjugate base to the weak acid.
CASE 1. From the Henderson-Hasselbach equation, calculate the ratio of dihydrogen phosphate (H2PO4-) and monohydrogen phosphate (HPO4-2) components required to produce buffer solution with
1. pH 6.2
2. pH 7.2
3. pH 8.2
CASE 2. From the Henderson-Hasselbach equation, calculate the ratio of acetic acid and acetate required to produce buffer solution with:
1. pH 3.7
2. pH 4.7
3. pH 5.7
Using the stock solution provided to you, make 25 mL of each of the buffer solutions assigned to you. Measure and record the pH of each of the buffer solutions. Add 2 mL of 0.1 M NaOH to each of the 25 mL buffer solutions. Record the pH of each buffer solution after addition of alkali. Account for the magnitude of pH shift in each with reference to the direction of pH shift.
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