How to prepare buffer?

Question

In a project, I have to prepare zinc stock solution with pH 4,5 n 6. But then my supervisor said that I have to use buffer instead of just adding NaOH and HCl. So, how can I prepare buffer?

Answer 1

Use the following site to cdecide on and then calculate reagent amounts:

http://bioinformatics.org/JaMBW/5/4/index.html

Remember that a buffer is a mixture of a weak acid and a weak base of the same species (ie. sodium phosphate and disodium phosphate).

Hope the site helps!

Answer 2

Take a weak acid-weak base couple with a pKa close to 4.5 and calculate the respective concentrations with the Henderson-Hasselbalch equation.