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In: Chemistry

How many grams of NaH2PO4 and how many grams of Na2HPO4 are needed to prepare 2.0...

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

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