Answer to Question #124589 in General Chemistry for Bryan

Question #124589
How would you prepare 250ml of 0.2m sodium phosphate buffer? ( pkm of phosphoric acid = 6.8 ), PH = 6.4
1
Expert's answer
2020-07-06T07:21:16-0400

Use Henderson Hasselbalch equation

pH = pKa + log([salt]/[acid])

pKa nearest to 6.8 is 7.2, therefore,

6.8 = 7.2 + log ([salt]/[acid])

-0.4 = log([salt]/[acid])

[Salt] = 0.398[acid]..........….........equation 1

[Acid] + [salt] = 0.2......................equation 2

Then you calculate the mass concentrations of the acid and salt.

The respective mass concentrations are to prepare 1000 ml of the buffer,

But to prepare 250 ml, divide the mass concentrations by 4.


Need a fast expert's response?

Submit order

and get a quick answer at the best price

for any assignment or question with DETAILED EXPLANATIONS!

Comments

No comments. Be the first!

Leave a comment

LATEST TUTORIALS
New on Blog
APPROVED BY CLIENTS