Fractional composition in a tetraprotic system. Prepare a fractional composition diagram

QUESTION:

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: (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 What concentration of Cr(OH)3(aq) is in equilibrium with solid Cr(OH)3(s)? (c) What concentration of Cr(OH)2 is in equilibrium with Cr(OH)3(s) if the solution pH is adjusted to 4.00? I