1. The problem statement, all variables and given/known data We did a lab in class about weak acid/strong base titration, but I'm having a bit of trouble. We we only given the molarities of an unknown weak acid and a strong base (NaOH) and the pH of six different mixtures containing different mL of the two, which is below: Test tube #1: 9mL of weak acid and 1mL of NaOH pH=3.04 Test tube #2: 8mL of weak acid and 2mL of NaOH pH=3.07 Test tube #3: 7.5mL of weak acid and 2.5mL of NaOH pH=3.40 Test tube #4: 7mL of weak acid and 3mL of NaOH pH=3.56 Test tube #5: 6mL of weak acid and 4mL of NaOH pH=3.80 Test tube #6: 5.5mL of weak acid and 4.5mL of NaOH pH=4.21 and the molarity of the solutions were .1176 for the unknown acid and .1059 for NaOH. 2. Relevant equations I was able to calculate the intial moles of the acid and base but were I'm having difficulty is figuring out the moles at equilibrium. (of A- and HA in HA + H2O = H3O +A-). 3. The attempt at a solution I'm very confused and was only able to get the intial moles of the acid and base. I know I'm supposed to use the Henderson-Hasselbaclh equation, but I don't know how to get log of (HA/A-) since I don't have HA or A-. Thanks!