Thread: Buffers.

I'm a new student of the course biochemistry. We had this topic about buffers a while ago. But I didn't understand it clearly. Can you guys help me answer this question:

A catalogue in the laboratory has a procedure to prepare 1L of a TRIS (N-tris [hydroxymethyl] aminomethane) buffer at 0.0500 M with a pH of 8. Dissolve 2.02 g of TRIS (free base, Molar Mass=121.1 g/mole) and 5.25 g of TRIS hydrochloride (acidic form, Molar Mass=157.6 g/mole) in a total volume of 1L. Verify if this procedure is correct.

That seems confusing to me, big time. Hehe. I'd appreciate it if you could help me. Thanks in advance. :-D

The calculations look right.

To check, determine the number of moles of TRIS you are told to use:

2.02 / 121.1

Then do the same for the TRIS-HCl:

5.25 / 157.6

These results are moles of solute added to 1L of solution. Add the two results and you will see that they total .05 moles of TRIS. Therefore we verify that you do indeed have a .05M solution of a TRIS buffer.

Originally Posted by SteveF

The calculations look right.

To check, determine the number of moles of TRIS you are told to use:

2.02 / 121.1

Then do the same for the TRIS-HCl:

5.25 / 157.6

These results are moles of solute added to 1L of solution. Add the two results and you will see that they total .05 moles of TRIS. Therefore we verify that you do indeed have a .05M solution of a TRIS buffer.

Wow. Thanks a lot SteveF. Much Appreciated. :-D