Consider the cell S.C.E. i cell solution | Pt(s), whose voltage is 20.126 V. The cell solution contains 2.00 mmol of Fe(NH₄)₂(SO₄)₂, 1.00 mmol of FeCl₃, 4.00 mmol of Na₂EDTA, and lots of buffer, pH 6.78, in a volume of 1.00 L.

(a) Write a reaction for the right half-cell.

(b) Find the quotient [Fe2+]/[Fe3+] in the cell solution. (This expression gives the ratio of uncomplexed ions.) 

(c) Find the quotient of formation constants: (Kf for FeEDTA²)/ (Kf for FeEDTA^2-).