1. Create a logC–pH diagram in Excel for an open carbonate system in equilibrium with CO2 (g) in the atmosphere. Assume that PCO2 = XXXXXXXXXXIf you add 0.2 mM of HCl to this system, what is the final...

1. Create a logC–pH diagram in Excel for an open carbonate system in equilibrium with CO2 (g) in the atmosphere. Assume that PCO2 = 10-3.5 . If you add 0.2 mM of HCl to this system, what is the final pH? Use the logC-pH diagram. *Show both Excel plots. Mark equilibrium pH on the second plot (with HCl added). Also mark the LHS and RHS equations on the plot using the TOTH balance. You do not need a line for HCL.2. A groundwater supply is initially at pH 8.0 and contains 2 x 10-3 eq/L alkalinity. a. If the alkalinity is all attributable to the carbonate system, determine whether the water is undersaturated or supersaturated with respect to atmospheric CO2. b. How much CO2 must be dissolved into or volatilized out of solution for the system to reach equilibrium with the atmosphere? c. What will the final pH and alkalinity be once equilibrium is attained?3. Two waters are in equilibrium with air, one at pH 9.5 and one at pH 7.3. These waters are mixed in 1:1 proportions. Assuming that carbonate species dominate the acid/base behavior of both solutions and that no gas transfer occurs when they are mixed (the system is now closed), determine the alkalinity and pH of the mixture. Will the mixture be undersaturated, supersaturated, or in equilibrium with atmospheric CO2?4. A question regarding water treatment and the importance of alkalinity when coagulating waters. The raw water supply for a community is at pH 7.5 and has ALK = 40 mg/L as CaCO3. Essentially all the alkalinity is attributable to the carbonate acid/base system. The water is treated by addition of 60 mg/L alum (Al2(SO4)3 14H2O) per liter of water, causing Al(OH)3 (s) to precipitate and aiding in the removal of colloidal matter from suspension. The precipitation of the alum generates acid by the reaction shown below: Al2(SO4)3 14H2O ---> 2Al(OH)3 (s) + 3SO42- + 6H+ + 12H2O a. It is desired to maintain a pH of at least 6.5 in the treated water (after coagulation and removal of the precipitates by settling and filtration). Will chemical (base) addition be necessary when the alum is added? If so, how much? Assume that gas exchange during the various treatment steps is slow enough that the solution can be treated as a closed system. b. If no base is added to the solution, will it be possible to reach the target pH by bubbling the treated water with air? How much CO2 must be stripped out of solution to reach the target pH?