1. The problem statement, all variables and given/known data Consider 1L of a solution that is 0.100 M in acetic acid and 0.100 M in sodium acetate. What will the pH be, when 0.0900 mol of sodium acetate are added? Ignore changes in volume. acetic acid pka = 1.75 E-5 2. Relevant equations HA --> H+ + A- pH=pka +log A-/HA 3. The attempt at a solution I had similar questions that I know how to do with strong acids. The difference in this question is that the added acid/base is a weak one. With the strong base addition I can just add it to A- concentration and subtract it from HA and use Henderson-Hasselbach equation. This one I tried that but the numbers I know are off. I also tried doing ka = H+*(0.1+.009)/0.1 Solving for H+ and then using that to find out concentrations of A- and HA but the H+ number is far too small to make a difference and I'm fairly sure I can't just add the conjugate bases together. Can someone please help.