Fractional composition in a tetraprotic system. Prepare a fractional composition diagram analogous to Figure 9-4 for the tetraprotic system derived from hydrolysis of Cr3+:
Cr3+ + (H2O) ⇌ Cr(OH)2+ + H+Ka1 = 10-3.80
Cr(OH)2+ + H2O ⇌ Cr(OH)+2 + H+Ka2 = 10-6.40
Cr(OH)+2 + H2O ⇌ Cr(OH)3(aq) + H+Ka3 = 10-6.40
Cr(OH)3(aq) + H2O ⇌ Cr(OH)-4 + H+Ka4 = 10-11.40
(Yes, the values of Ka2 and Ka3 are equal.)
(a) Use these equilibrium constants to prepare a fractional composition diagram for this tetraprotic system.
(b) You should do this part with your head and your calculator, not your spreadsheet. The solubility of Cr(OH)3 is given by W
Cr(OH)3(s) ⇌ Cr(OH)3(aq) K = 10-6.84
what concentration of Cr(OH)3(aq) is in equilibrium with solid Cr(OH)3(s)?