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^-, pK_a = 7.21 and K_a = 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

Expert Solution

queen_honey_blossom answered 8 months ago

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