The following figure shows EH versus pH diagram for chromium in water at 25^oC. a) From the figure, determine the dominant form of chromium at pH = 7 and pe = 12. b) Develop a balanced oxidation-reduction reaction for the conversion of CrO4^2- to Cr(OH)₃(s) in the presence of elemental iron, which reacts to form Fe²⁺. Show the relevant half reactions, identify the oxidation and reduction half reactions, note the oxidation state of each redox-active element, and give the balanced net reaction. c) For a system with CrT = 10^-5 M, use Figure to help determine the concentrations of the species CrO₄^2- and Cr³⁺ at pH = 7.0 and EH = 100 mV. Calculate the concentration of total dissolved Cr under these conditions.

1 HCrO4 .5 Cri 3+ croa Eh (volts) Croft O 3- Cros Cr(OH)3(am) -.5 Cr(OH) 25C 0 2 4 6 8 10 12 14 pH 1 HCrO4 .5 Cri 3+ croa Eh (volts) Croft O 3- Cros Cr(OH)3(am) -.5 Cr(OH) 25C 0 2 4 6 8 10 12 14 pH