1. The problem statement, all variables and given/known data prepare 40mM TES buffer pH 7.4 prepare 100mls of it mw TES = 229.25 pka = 7.5 2. Relevant equations ph = pka +log(A-/HA) 3. The attempt at a solution My problem is that I don't know what the MW of the acid or base is for this buffer. Is the given MW the acid, and I subract a proton weight for the base or something? I can do the calculation though: 7.4 = 7.5 +log(A-/HA) -.1 = log(A-/HA) A-/HA = .79 56% base 44% acid .56* 40mM * MW of base *.1L = moles of base .44*40mM *MW of acid *.1L = moles of acid So how should I figure out the MW of acid and base?