The maximum contaminant level (MCL) for barium (Ba) in drinking water is 2.0 mg/L. Barium can combine with sulfate (SO42-) to form BaSO4(s), which precipitates out of the water. This can be achieved by adding Na2SO4. You are to use your knowledge of equilibrium chemistry and solubility to answer the following: (a) What level of SO42- is required to reduce Ba2+ to the MCL? Assume there are no complexes with Ba2+ or SO42-. (b) For a flow of 1 MGD and an initial Ba2+ concentration of 10 mg/L, how much Na2SO4 must be added (lb/day) to accomplish removal of Ba2+ to the MCL? (c) Briefly discuss what the limitations might be in using precipitation of BaSO4(s) to remove Ba2+ from potential drinking waters. The following might be useful: BaSO4(s) = Ba2+ + SO42- pKsp = 10