100.-mL sample of 0.100 M solution of Ca2+ ions is being complexometrically titrated with 0.100 M EDTA. pH of the solution is being maintained at 9.0 by a buffer. Acidity constants of EDTA are: Ka1 = 1.0×10^-2, Ka2 = 2.2×10^-3, Ka1 = 6.9×10^-7, Ka2 = 5.5×10^-11 Formation constants of the Ca-EDTA complex is Kf = 5.01×10^10

Relevant textbook example: 9.3

(a) Calculate the fraction of EDTA that exists as fully deprotonated anion Y4- at pH 9.0