Question

As a technician in a large pharmaceutical research firm, you need to produce 100.mL of 1.00 M potassium phosphate buffer solution of pH = 6.77. The pK a of H 2 PO 4 − is 7.21.
You have the following supplies: 2.00 L of 1.00 M KH 2 PO 4 stock solution, 1.50 L of 1.00 M K 2 HPO 4 stock solution, and a carboy of pure distilled H 2 O .
How much 1.00 M KH 2 PO 4 will you need to make this solution?