1. The problem statement, all variables and given/known data Phosphate, present to an extent of 0.01 M, is one of the main buffers in blood plasma, whose pH is 7.45. Would phosphate be as useful if the plasma pH were 8.5? 2. Relevant equations pH = pKa+log[A/HA] Ka1 = 7.11x10^-3 pka1= 2.148 Ka2=6.34x10^-8 pka2= 7.198 Ka3 = 4.22x10^-13 pka3=12.375 3. The attempt at a solution Since the pH would still be between pka2 and pka3 so the phosphate would not gain or lose a hydrogen because of that change and the henderson-hasselbalch equation would still use the same pka. Does this mean it would be just as effective at pH 8.5 or am I missing something?