The solubility of \(\mathrm{CaCO}_{3}\) is pH dependent.
(a) Calculate the molar solubility of \(\mathrm{CaCO}_{3}\left(K_{s p}=4.5
\times 10^{-9}\right)\) neglecting the acid-base character of the carbonate
ion. (b) Use the \(K_{b}\) expression for the \(\mathrm{CO}_{3}^{2-}\) ion to
determine the equilibrium constant for the reaction
\(\mathrm{CaCO}_{3}(s)+\mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons
\mathrm{Ca}^{2+}(a q)+\mathrm{HCO}_{3}^{-}(a q)+\mathrm{OH}^{-}(a q)\)
(c) If we assume that the only sources of \(\mathrm{Ca}^{2+},
\mathrm{HCO}_{3}^{-},\) and \(\mathrm{OH}^{-}\) ions are from the dissolution of
\(\mathrm{CaCO}_{3},\) what is the molar solubility of \(\mathrm{CaCO}_{3}\) using
the preceding expression? What is the \(\mathrm{pH} ?\)
(d) If the \(\mathrm{pH}\) is buffered at 8.2 (as is historically typical for
the ocean), what is the molar solubility of \(\mathrm{CaCO}_{3} ?\) (e) If the
\(\mathrm{pH}\) is buffered at \(7.5,\) what is the molar solubility of
\(\mathrm{CaCO}_{3} ?\) How much does this drop in \(\mathrm{pH}\) increase
solubility?
solution remains \(0.50 \mathrm{~L},\) calculate the \(\mathrm{pH}\) of the
resulting solution.
