[Mashudu]

Calculation on how to prepare the following buffer. Solution. 1)100ml of a 20mM Tris-HCl buffer, pH 8.2, containing 100mM NaCl and 0.02% NaN3.                              PLZ HELP ME, I COMPLETELY DON'T KNOW WHERE TO START

[Hunter2]

Do you know what mM means? If you know that you can calculate the moles of the solution of 100 ml. With the molecular weight the mass as well. For the Percentage normally you need the specific gravity of the 100 ml, in this concentration I suppose its still close to 1 g/cm³.  You can calculate then also the mass of sodiumazide.

[Mashudu]

I know that: 1 mol/L =1000mM, therefore 20mM=0.02mol/L, but I've never being taught how to calculate buffer calculations. I've been look for example in text book, but honestly I don't understand. Most. What the 0.02% NaN3 (sodium azide) is for.

[Borek]

TRIS and HCl are for creating buffer, everything else are just additives (ie they are necessary for some reason, but they can be ignored when calculating buffer recipe - unless you are expected to take ionic strength of the solution into account).

[Hunter2]

I know that: 1 mol/L =1000mM, therefore 20mM=0.02mol/L, but I've never being taught how to calculate buffer calculations. I've been look for example in text book, but honestly I don't understand. Most. What the 0.02% NaN3 (sodium azide) is for.

One Hint: check pkS Value of the TRIS. You had a given pH of 8.2.  So is the coin fallen down?