Problem- 1) A biochemist wishes to prepare various phosphate buffers by mixing together two 0.20 M solutions that contain either sodium dihydrogen phosphate (NaH2PO4) or disodium hydrogen phosphate (Na2HPO4).
2) In what ratio should these solutions be combined to give a buffer with pH of 7.0, with pH of 6.5, and with pH of 7.5?
3) If a total volume of 1.00 L is needed for a pH 7.2 buffer solution, what volumes of the original two solutions will be needed to prepare this buffer? What mass of the solids Na2HPO4•2H2O and NaH2PO4•2H2O will be needed to prepare these solutions?
Articulate your answer to two significant figures as well as comprise the appropriate units.