In: Chemistry
How many grams of NaH2PO4 and how many grams of Na2HPO4 are needed to prepare 2.0 L of 1.50 M “phosphate buffer” with a pH of about 8.00.
You are given:
For salt form of a weak acid NaH2PO4 or weak acid H2PO4-, pKa = 7.21 and Ka = 6.2 x 10-8
1 mol Na2HPO4 = 142 g Na2HPO4
1 mol NaH2PO4 = 120 g NaH2PO4
Select one:
a. Mass of NaH2PO4: 35.5 g and Mass of Na2HPO4: 276.1 g
b. Mass of NaH2PO4: 70.6 g and Mass of Na2HPO4: 392.9 g
c. Mass of NaH2PO4: 50.2 g and Mass of Na2HPO4: 366.5 g
d. Mass of NaH2PO4: 37.9 g and Mass of Na2HPO4: 312.8 g
e. Mass of NaH2PO4: 75.3 g and Mass of Na2HPO4: 408.1 g