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