The solubility of CaCO₃ is pH dependent.

a) Calculate the molar solubility of CaCO₃ (K_sp = 4.5 × 10^-9) neglecting the acid–base character of the carbonate ion.

(b) Use the expression for the CO₃^2- ion to determine the equilibrium constant for the reaction

(c) If we assume that the only sources of Ca²⁺, HCO₃^-, and ions are from the dissolution of CaCO₃, what is the molar solubility of CaCO₃ using the preceding expression? What is the pH?

(d) If the pH is buffered at 8.2 (as is historically typical for the ocean), what is the molar solubility of CaCO₃?

(e) If the pH is buffered at 7.5, what is the molar solubility of CaCO₃? How much does this drop in pH increase solubility?

Transcribed Image Text:

CaCO3(s) + H,O(I) = Ca2+(aq) + HCO; (aq) + OH (aq)