Citrate Complex of Chromium

Chromium citrate complex has been studied by pH titration method. Cr3+ reacts with the citrate ligand at lower pH forming a neutral complex C liberating three protons. At higher pH the complex C dissociates to anionic complexes C1- and C2- in two steps. The equilibrium constants of the reechoes \(Cr_{3+}+H_3Cit \rightleftharpoons C+3H^+, \) \(C \rightleftharpoons C_1^-+H^+\)and \(C_1^-\rightleftharpoons C_2^{-2}+H^+\) are found to be 2.79 X 10-6, 6.40 X 10-6 and 9.16 X 107 at 25°C respectively. The hydrolytic constant for the hydrolysis of Cr3+ according to the equation \(Cr_{3+} +H_2O\rightleftharpoons CrOH^{3+} +H^+\) is found to be 4.58 X 10-1