Biochem Ph Problem

vcuram

1. The problem statement, all variables and given/known data

Solid Na2HPO4 is dissolved in water. What is the resulting pH of the solution? Relative pka's of phosphate derivaties are ~2, ~7, and ~12.

2. Relevant equations

No equation needed, just look at the species which phosphate would develop.


3. The attempt at a solution

I believe the specified compound would be in equilibrium between one of these species;
H3PO4, H2PO4 (-), HPO4 (-2) and PO4 (-3). The choices are 12, 7, 2, 9, or there is not enough information.

Borek

pH of amphiprotic salt solution

vcuram

Thank you very much! If I understand correctly then the answer would be 1/2 (7 +12) which would be ~ 9 ph?

That is the answer I chose. Thank you.