I think that is what you call it. I need to find the pH of a solution containing 50 grams of Na3PO4. 50 g ---- > 0.305 M We know that Kw=Ka*Kb So, Na3PO4 + H20 --> HNa3PO4 + OH (I think) Kb = x^2/(.305-x) I cant find the value of Kb anywhere in my book, internet. If I had it I could calculate Ka and get my pH. Otherwise Im stumped.