Combine 10 mL of acetic acid and 10 mL of sodium acetate of the same concentration to form an equal molar acetic acid-sodium acetate buffer. Split the solution into equal parts. To one half, add 1 mL increments of 0.8 M HCl until the buffer capacity is exceeded (3.57) and to the other half add 1 mL increments of 0.8 M NaOH until the buffer capacity is exceeded (5.57).

Calculate the concentrations of acetic acid and sodium acetate after the first two additions. From these values and the pH, calculate the equilibrium constant.

HCl added pH. NaOH added pH

1 mL 4.75 1 mL 4.78

2 mL 4.58 2 mL 4.92

3 mL 4.41 3 mL 5.11

4 mL 4.18. 4 mL 5.30

5 mL 3.90. 5 mL. 5.65

6 mL. 3.41 6 mL 9.43

7 mL 2.00