What is the pH of a 0.115 mol/L solution of sodium acetate, CH3COONa, at 25oC? (pKa=4.74 at 25oC for CH3COOH.)

Answer 1

The pH is determined by the hydrolysis of the CH3COONa, which I will call NaAc.
.........Ac^- + HOH --> HAc + OH^-
I.......0.115............0.....0
C.......-x...............x.....x
E.....0.115-x............x.....x

Kb for Ac^- = (Kw/Ka for HAc) = (x)(x)/(0.115-x)
Substitute and solve for x = OH^- and convert to pH.

Answer 2

find Kb from pKa

Find CH3COO- concentration

Use ICE table to find concertation of OH-

Find pH from there