How would i make phosphate buffer 0.3M pH 6.5 1L using sodium mono and dibasic solutions?
Equation 1 is the Henderson-Hasselbalch.
pH = pKa + log (base)/(acid)
6.5 = pKa2 + log (Na2HPO4)/(NaH2PO4)
Solve for the ratio base/acid. That's equation 1.
Equation 2 is
(Na2HPO4) + (NaH2PO4)= 0.3 M
Solve the two equations simultaneously for
(Na2HPO4) and (NaH2PO4). Those numbers will be in M. Then convert the molarity of each into grams for a 6.5 L solution (or whatever that 6.5 1L volume means).