# Biochemistry

posted by .

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 -

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 -

I am a little confused on the part after you solve for 26 grams. Can you explain a little more? Thanks

## Similar Questions

Calculate the weight of the buffers you will use to make the buffers for Part A for all the buffer possibilities listed under procedures in Part A, step 1. In other words, how many grams do you need to make 100 mL of a 0.1 M buffer?
2. ### chemistry

I have already posted this and never got a response, please help. here is my data from lab: Buffer1: HPO4- weight 3.412g; original pH Buffer 2: HEPES wt: 1.090g original pH 10.08 buffer1: pH of 0.1M: 7.5; pH of 0.01: 7.72; pH of 0.001M: …
3. ### science(chem)

The pKa of HEPES is 7.55 at 20C and it's MW is 238.31. Calculate the amounts of HEPES in grams and of 1.0M NaOH in ml that would be needed to make 300ml of 0.2M HEPES buffer at 7.2. I'm not sure how to go about doing this problem. …
4. ### chemistry

The pKa of HEPES is 7.55 at 20 degrees C, and its MW is 238.31. Calculate the amounts of HEPES in grams and of 1.0 M NaOH in milliliters that would be needed to make 300 mL of 0.2 M HEPES buffer at pH 7.2.
5. ### Biochem

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 …
6. ### Biochemistry

Do you add Nacl or HCL if your target buffer pH is 8, and the buffer is HEPES
7. ### Chemistry

If you start with 200 ml of 0.1M HEPES buffer (pH 7.5) and add 1.25 ml of 0.5M HCl, what will the final pH be?
8. ### Biochem

We will need 0.5L extraction buffer with 25 mM HEPES, 1 mM EDTA, and 1 mM DTT. Please calculate how many grams of each solute are needed. (HEPES 238.3; EDTA 292.2; DTT 154.2)
9. ### Biochemistry

If you make up a solution of 100mL of 0.1 M Hepes in the basic form, what will be the pH?
10. ### BioChemisty

You have a 0.5 M HEPES pH 7, and a 0.5 M HEPES pH 8 solution. How much of each stock solution do you need to make 125mL of a 50 mM HEPES pH 7.5 solution?

More Similar Questions