lauraK

Problem: Need to prepare a 250 mL buffer of pH 7.00 using equimolar K2HPO4 and KH2PO4 solutions. Ka for phosphoric acid: Ka1=7.2 x 10^-3 Ka2=6.3 x 10^-8 Ka3=4.2 x 10^-13 I though the hard part of this was picking the right equation/Ka value, but I am not...

First--how did you try to solve the problem? If you do not know where to start, I suggest you draw a picture of the fence and then write down what you know about each side.