1. The problem statement, all variables and given/known data I am trying to prepare a 1L Tris-HCl buffer 1M pH7. The pKa value is 8.06. The question is, how many molar of HCl should be added to produce this buffer? 2. Relevant equations pH = pKa + log [base/acid] 3. The attempt at a solution 7=8.06 + lg (a/b) -1.06=lg (a/b) a/b = 0.0871 -----1 a+b= 1M a=1-b --------2 Hence, (1-b)/b = 0.0871 b = 0.92M a = 0.08M So, the molarity of HCl to be added is 0.92M or 0.08M. Why?