This problem will take you through the steps needed to calculate the appropriate mass of Tris base, EDTA, and salt (NaCl in this example), and volume of 1 N HCL to use in the preparation of your Tris buffer stck solution for the enzyme kinetics unit. The final volume, concentrations and pH values have been randomized, and are not necessarily the values you have been assigned to use in your stock solution. The formula weight for Tris is 121.1 g/mole, EDTA is 372.2 g/mole, and NaCl is 58.44 g/mole.
Tris base is uncharged (conjugate base), and Tris-HCl has a charge of +1 (conjugate acid).
The pKa' for Tris is 8.2 (use this value in the initial calculation of the Henderson-Hasselbalch equation to determine the CB/CA ratio).
When you solve the final Henderson-Hasselbalch equation to calculate more precisely the amount of HCl to add, use the pKa (8.08) plus your calculated ΔΔpKa.
Provide three significant figures and include units, when appropriate, in your answers
You wish to make 85.0 mL of 158 mM Tris buffer pH 8.20, containing 25.5 mM EDTA and 43.5 mM NaCl.
What mass of Tris base would you need to weigh out?