CH3COOH and CH3COONa is an acidic buffer. It retains the pH when acid is added as CH3COO-+H3O+ <==> CH3COOH+H2O. This reduces the amount of H3O+ allowing a smaller change in pH. It also increases the concentration of the CH3COOH. However, I was thinking about this other equation CH3COOH+OH- <==> CH3COO- +H2O. So my concentration of the acetate ion remains relatively constant due to the high concentrate from the CH3COONa. So after the first reaction happens, the concentration of the acetate acid increases. So wouldn't there be an equilibrium shift to the left increasing the amount of OH- ions?