Question

What is the pH of a solution that contains 0.30 M HC2H3O2 and 0.95 M C2H3O2-? Use Ka = 1.8 × 10-5 for HC2H3O2.

Answer 1

HC2H3O2 = HAc = acetic acid
C2H3O2^- = Ac^- = acetate ion

...........HAc --> H^+ + Ac^-
I........0.30......0....0.95
C..........-x......x......x
E........0.30-x....x....0.95+x

Ka = (H^+)(Ac^-)/(HAc)
1.8E-5 = (x)(0.95+x)/(0.30-x)
Solve for x and convert to pH.