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2) Barium (Ba) is a toxic metal that may be found at trace levels in drinking water. The national primary drinking water regulations limit Ba in municipal drinking water to 2 mg/L. The drinking water in many communities in Turkey can contain barium at five times the standard. Barium can be removed from drinking water by precipitation as barium carbonate, BaCO3. Consider the following situation. Untreated water contains 10 mg/L Ba?, 100 mg/L Ca' and 350 mg/L HCO3 and is at a pH of 7. (Other ions may be present but are of no consequence here). Sodium hydroxide (NaOH) is to be added to the water to raise the pH and cause Baco, to precipitate. Some of the calcium may precipitate as CaCO3 as well: BaCO3) = Ba2+ + CO K = [Ba * Ico] = 8. 1x10-ⓇM CaCO3(x) = Caz* +CO K K =Calco]=8.7x10°M = () a) (10 p) Determine the total hardness, carbonate hardness, and non-carbonate hardness of the untreated water (mg/L CaCO3). b) (10 p) What is the minimum carbonate concentration (M) for which the equilibrium barium concentration satisfies the standard? c) (10 p) At the carbonate concentration (M) required in part (a), how much calcium will remain in solution at equilibrium?