Calculate the molar solubility of \mathrm{BaSO}_{4}.
Begin by writing the reaction by which solid \mathrm{BaSO}_{4} dissolves into
its constituent aqueous ions.
Next, write the expression for K_{\mathrm{sp}}.
K_{\mathrm{sp}}=[\mathrm{Ba}^{2^{+}}][\mathrm{SO}_{4}^{2{-}}]Define the molar solubility (S) as [{ B}a^{2+}]\ \mathrm{or}\ [\mathrm{SO}_{4}^{\ 2-}] at equilibrium.
S=[Ba^{2+}]=[SO_{4}^{2-}]Substitute S into the equilibrium expression and solve for it.
\begin{array}{c}{{K_{\mathrm{sp}}=[{ Ba}{}^{2+}][{ S}\mathrm{O}_{4}{}^{2-}]}}\\ {{={}S\times S}}\\ {{=S^{2}}}\end{array}Therefore
S={\sqrt{K_{\mathrm{sp}}}}Finally, look up the value of K_{\mathrm{sp}} in Table 15.2 and calculate S. The molar solubility of \mathrm{BaSO}_{4} is 1.{{0}}3\times10^{-5} mol/L.
\begin{array}{l}{{S=\sqrt{K_{\mathrm{sp}}}}}\\ {{=\sqrt{1.07\times10^{-10}}}}\\ {{=1.03\times10^{-5}\,\mathrm{M}}}\end{array}Table 15.2 Selected Solubility-Product Constants (K_{sp}) | ||
Compound | Formula | K_{sp} |
barium sulfate | BaSO_4 | 1.07\times10^{-10} |
calcium carbonate | CaCO_3 | 4.96\times10^{-9} |
calcium fluoride | CaF_2 | 1.46\times10^{-10} |
calcium hydroxide | Ca(OH)_2 | 4.68\times10^{-6} |
calcium sulfate | CaSO_4 | 7.10\times10^{-5} |
copper(II) sulfide | CuS | 1.27\times10^{-36} |
iron(II) carbonate | FeCO_3 | 3.07\times10^{-11} |
iron(II) hydroxide | Fe(OH)_2 | 4.87\times10^{-17} |
lead(II) chloride | PbCl_2 | 1.17\times10^{-5} |
lead(II) sulfate | PbSO_4 | 1.82\times10^{-8} |
lead(II) sulfide | PbS | 9.04\times10^{-29} |
magnesium carbonate | MgCO_3 | 6.82\times10^{-6} |
magnesium hydroxide | Mg(OH)_2 | 2.06\times10^{-13} |
silver chloride | AgCl | 1.77\times10^{-10} |
silver chromate | Ag_2CrO_4 | 1.12\times10^{-12} |
silver iodide | AgI | 8.51\times10^{-17} |