[Boxxxed]

20 ml of 0.5 M CH3COOH is titrated with 20 ml of 0.5 M NaOH. what is pH? (pka=4.76)

0.010 moles CH3COOH
0.010 moles NaOH

CH3COOH+OH------->CH3COO- + H2O
0.010 moles CH3COO- forms in 40 ml

0.010 mole base / 0.04 L = 0.25 M

Kb = kw/ka = 5.7x10^-10

Equilibrium
CH3COO- + H2O--------->CH3COOH+OH

kb= x² / 0.25-x

x= Sqroot (0.25)(5.7x10^-10)

POH = 5.42

pH = 8.58??

[Borek]

Correct approach but lousy math.