Posted by **Angel** on Tuesday, September 14, 2010 at 10:48pm.

Sorry!

HEPES, is a commonly used component of physiological buffers. The PKa of the protonated amino group of HEPES is 7.55 at 25C.

Describe the preparation of 1.00L of 0.100M HEPES buffer, pH 8.00, from the sodium salt of the basic form of HEPES (MW 260.3), 6.0M HCl and deionized water

- Biochemistry -
**DrBob222**, Tuesday, September 14, 2010 at 11:14pm
B = base

A = acid = BH^+

B.Na + H^+ ==> A (BH^+)

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

Plug in 8.00 for pH, 7.55 for pKa, and solve for ratio B/A.

You need another equation since there are two unknowns; and that one is A + B = 0.1M

Solve for A and B.

Then I would start with 0.1 mole B.Na which is 0.1 x 260.3 = ?? grams (I think about 26 grams). You know the concn needed for the acid and that MUST equal the H^+ needed. That will give you L of the 6M HCl needed and that should do it. Post your work if you get stuck. I arrived at about 26 grams of the sodium salt and about 4.5 mL of the acid (actually a little less), then make the solution to a final volume of 1.00 L in a volumetric flask.

- Biochemistry -
**Needhelp**, Wednesday, September 15, 2010 at 5:05am
I am a little confused on the part after you solve for 26 grams. Can you explain a little more? Thanks

## Answer This Question

## Related Questions

- Biochem - HEPES, is a commonly used component of physiological buffers. The PKa ...
- chemistry - The pKa of HEPES is 7.55 at 20 degrees C, and its MW is 238.31. ...
- science(chem) - The pKa of HEPES is 7.55 at 20C and it's MW is 238.31. Calculate...
- Chemistry - If you start with 200 ml of 0.1M HEPES buffer (pH 7.5) and add 1.25 ...
- BioChemisty - You have a 0.5 M HEPES pH 7, and a 0.5 M HEPES pH 8 solution. How ...
- Biochem - We will need 0.5L extraction buffer with 25 mM HEPES, 1 mM EDTA, and 1...
- chemistry - I have already posted this and never got a response, please help. ...
- biochemistry with more info that was needed - Calculate the weight of the ...
- Biochemistry - If you make up a solution of 100mL of 0.1 M Hepes in the basic ...
- Biochemistry - Do you add Nacl or HCL if your target buffer pH is 8, and the ...

More Related Questions