Redox reactions are also important to consider when studying the behavior of uranium in the environment. Uranium mill tailings often release UO₂(aq)²⁺ to local streams. Consider the following reaction: Gf FeOOH= -490.6 kJ/mol FeO(wustite) + UO₂(aq)²⁺ FeOOH(goethite) + UO₂(uraninite) This is not balanced- you will balance this by adding H+, H₂O, and/or O₂ (aq) by the end of the problem.

Part A. What is the standard voltage (E) for the reduction cell reaction?

Part B. Calculate the equilibrium constant (K_eq) for this reaction. Based on this calculation, what is the predicted activity of UO₂²⁺(aq) at pH = 5 at equilibrium?

Part C. Based on the equilibrium constant, what would you expect to happen if you added wustite to a stream contaminated with UO₂²⁺(aq) ? Would this be an effective way to prevent UO₂^{2+ (}aq) from being transported further downstream? Why or why not?

Feo H+ H4Sio4 Fe2+ Fe3+ 02 aq G (kJ) H (kJ) S (1) -245.12 -266.27 0 0 -1307.67 -1449.36 -78.9 -89.1 -4.7 -48.5 16.4 -11.7 -237.129 -285.83 -742.2 -824.2 -245.12 -266.27 -487.02 -953.5 -1019.6 -1031.7 -1084.9 G (1) H() 57.49 -266270 -266270 0 0 0 215.132 -1307669 -1449359 -137.7 -78900 -89100 -315.9 -4700 -48500 110.9 16400 -11700 69.91 -237129 -285830 87.4 -742200 -824200 57.49 -245120 -266270 -487020 0 -97.5 -953500 -1019600 77.03 -1031700 -1084900 H201 Fe203 Feo FeOOH UO2 2+ UO2