[rock_lee225]

I have a example problem, and worked it out but not sure its right.

ques

How many mls of the following would you use to make 1 liter of 0.1 M Tris-HCL, pH 8.2 at 25 C?

1 M Tris base_____mls
1 M HCL       _____mls
H2O            _____mls

I got 100, 42, 858, respectively when i calculated it out. Not sure if this is right.  if someone can please work this problem out in steps with an explanation, that would be greatly appreciated.

[Borek]

Looks about OK to me. 100 mL of TRIS is obvious - that gives you 0.1M solution at the end. Then you need to use Henderson-Hasselbalch equation to find out the ratio of conjugates - and it looks like yiu did it well. Listing volume of water doesn't make much sense, as in lab practice you will just fill up to 1000 mL, besides, volumes are not additive - so I am absoluteli sure that your final volume will be not exactly 1000 mL, although you did your best and there is not much more that can be done in this case.

My results are slightly different, but Buffer Maker calculates ionic strength of the solution and takes activity coefficients into account.