3. (30 points) Injection of CO2 into deep groundwater has been proposed as a means of sequestering CO2 emissions from coal-fired power plants. In such a case, CO2 from a power plant's exhaust would be injected until the groundwater comes to equilibrium with pco2 (up to 10 atm) in the exhaust.** (a) (20/30 points) Set up expressions to solve for [H2CO3*], [HCO3 ], [CO32-], [Ca2+], TOTc03 (or Ct), and Alk of the groundwater in terms of pco2 and [H']. Provide brief explanations for how you would solve for these values by hand or by computer, including how you would solve for the value of pH needed to obtain them. (No actual calculations necessary.) You can assume that the groundwater [Ca2+] is in equilibrium with the surrounding aquifer solids (CaCO3(s)). Hint: Remember to take into account the charge balance for the system. **You can assume that T = 25 C. Recall that Ka,H2CO3/HCO3. = 10-6.35, KaHCO3-/CO32- = 10-10.33, and Kw = 10-14. Also recall that Ksp, Caco3 = 10-8.42 for the equilibrium CaCO3(8) = Ca2+ + CO32-, and that KH.co2 = 10-1.47 (mol/L)/atm for the equilibrium CO2(g) + H20 = H2CO3*. = = (b) (10/30 points) How would you expect CO2 injection to affect the equilibrium Alk, pH, TOTC03, and Ca+ concentration in the groundwater (i.e., increase or decrease) compared to a reference case in which the groundwater is not injected with CO2? Please include a sentence or two in each case to explain your reasoning (Again - no calculations necessary.) Hint: You may find the Deffeyes diagram helpful here