Question

a) Which of the two of the following compounds would you mix to make a buffer...

a) Which of the two of the following compounds would you mix to make a buffer of pH 7.45 phosphoric acid (FM=98.00), sodium dihydrogen phosphate (FM=119.98), disodium hydrogen phosphate (FM=141.96), or sodium phosphate (FM=163.94)?

b) If you wanted to prepare 1.pp L of buffer with a total phosphate concentration of 0.0500M, how man grams of the selected compounds would you mix together?

c) If you did what you calculated in part (b), you would not get a pH of exactly 7.45. Explain exactly how you would really prepare the buffer in the lab.
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Answer #1

question a

Which of the two of the following compounds would you mix to make a buffer of pH 7.45 phosphoric acid (FM=98.00), sodium dihydrogen phosphate (FM=119.98), disodium hydrogen phosphate (FM=141.96), or sodium phosphate (FM=163.94)?

a) NaH2PO4

and

Na2HPO4

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b) If you wanted to prepare 1.pp L of buffer with a total phosphate concentration of 0.0500M, how man grams of the selected compounds would you mix together?

(answer

4.55 g Na2HPO4 + 2.15 g NaH2PO4

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(c

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