Question

You have 1 M solutions of H₃PO₄, NaH₂PO₄, Na₂HPO₄, Na₃PO₄ (no NaOH).

=> Using only two of these solutions, how would you prepare 150 mL of 1 M phosphate buffer at pH 3.0?

A)		131.4 mL of NaH2PO4 + 18.6 mL H3PO4
B)		50 mL Na2HPO4 + 100 mL Na3PO4
C)		75 mL Na2HPO4 + 75 mL Na3PO4
D)		18.6 mL of NaH2PO4 + 131.4 mL H3PO4