Question

Describe in detail how you will prepare 500.0 mL of 0.040 M HEPES buffer at pH...

Describe in detail how you will prepare 500.0 mL of 0.040 M HEPES buffer at pH 7.45. In your answer, indicate how much(grams) of HEPES you will dissolve in what volume (mL), and what you will use to adjust the pH(NaOH or HCl).

Homework Answers

Answer #1

HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) is acidic.

Molecular weight of HEPES is 238.30

0.040 M solution is = 238.30 x 0.040 = 9.532 g in one liter

so for 500 ml = 9.532 / 2 = 4.766 g

Take suitable container and add 4.766 g of HEPES in to the container and make up to 450 mL with distilled water.

Add solid NaOH with constant sirring up to reach the pH -7

Then add concentrated NaOH solution dropwise and stirr well to reach the pH - 7.45.

and make up to 500 mL by distilled water.

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