1.) A diprotic acid has the following pK values: pKa1= 5.50, pKa2 = 9.50
a.) At what pH does [H2A] = [HA- ]?
b.) At what pH does [HA- ] = [A2- ]?
c.) Which is the principal species at pH = 3.50, H2A,HA- , or A2- ? Justify your answer using theHenderson-Hasselbach equation.
d.) Which is the principal species at pH = 7.5, H2A,HA- , or A2- ? Justify your answer (don’t useHenderson-Hasselbach equation, this is a half-neutralized diproticacid).
e.) Which is the principal species at pH = 9.8, H2A,HA- , or A2-? Justify your answer using theHenderson-Hasselbach equation.
