Buffer is prepared by adding 0.5 mol of solid sodium hydroxide to 1.0 L of 1.0 M acetic acid (CH3COOH).

Question

What is the pH of the buffer?

a. The pH will be pKa – 0.30, where pKa is that of acetic acid.

b. The pH will be greater than the pKa for acetic acid.

c. The pH will be less than the value in answer a.

d. The pH will be equal to the pKa for acetic acid.

e. More information is needed to solve the problem.

Answer 1

d. The pH will be equal to the pKa for acetic acid.

0.5 moles of NaOH destroys 1/2 of the acetic acid, this leaves 0.5 moles of acid, but produces 0.5 moles of sodiium acetate

CH3COOH -->  H+  & CH3COO-

K = [H+] [CH3COO-] /[CH3COOH]

K = [H+] [0.50] /[0.50]

K = H+

your answer is : pK = pH  at 1/2 reactions