Question

1. Calculate pH of an acetate buffer containing 27.5 mM acetic acid (pKa is 4.74) and 50 mM sodium acetate. When a 30 mM aq solution of sodium acetate was prepared in the lab it had a pH of 8.8. Calculate the amount of acetic acid (in g) to be added to 0.5 L of this sodium acetate solution in order to bring its pH to the target value of 5.00.

Answer 1

a. pH = 4.74 + log(base)/(acid) = approx 5.00

b.
millimoles NaAc = mL x M = 500 mL x 0.030M = = 15 mmoles.
5.00 = 4.74 + lot (15/x)
Solve for x = millimoles acetic acid and convert that to grams in 500 mL solution.

Answer 2

Thank you :)