What mass of K2HPO4 must be added to 1 L of .1 M K3PO4 to prepare a buffer solution with a pH of 10.8? Answer in units of grams.

Answer 1

pH = pK3 + (K3PO4^3-)/(K2HPO4^2-)
Plug in the numbers and solve for (K2HPO4^2-) in M = mols/L.
Then mols = M x L = ?
and mols = grams/molar mass. You know molar mass and mols, solvle for grams.