1. The problem statement, all variables and given/known data The cid constants for the polyprotic acid H3AsO4 are Ka1=5x10^-3, Ka2=8x10^- 8, Ka3=6x10^-10. What is the pH of a 0.1M Na2HAsO4 solution? 2. Relevant equations Kb = [H2A]*[OH]/[HA] mass balance, charge balance.. etc. 3. The attempt at a solution Well I've tried setting up a bunch of equations but I can't do this. Does anyone have any tips?