Precipitation reactions and solubility rules Transitional Reasoning Practice

Questions

1. 1.

   A chemist dissolves 1.204 g of an unknown water-soluble group 2 metal sulfate, $M\text{SO}_4$, in water and adds an excess of aqueous barium chloride, $\text{BaCl}_2(aq)$, causing an insoluble white precipitate to form. After the mixture is filtered, washed, and dried to constant mass, exactly 2.334 g of dry barium sulfate, $\text{BaSO}_4$, is recovered. Based on solubility rules and reaction stoichiometry, what is the chemical formula of the original metal sulfate, and what is the net ionic equation for the precipitation reaction?

   • A) $\text{CaSO}_4$; $\text{Ba}^{2+}(aq) + \text{SO}_4^{2-}(aq) \rightarrow \text{BaSO}_4(s)$
   • B) $\text{MgSO}_4$; $\text{Mg}^{2+}(aq) + 2\text{Cl}^-(aq) \rightarrow \text{MgCl}_2(s)$
   • C) $\text{BeSO}_4$; $\text{Ba}^{2+}(aq) + \text{SO}_4^{2-}(aq) \rightarrow \text{BaSO}_4(s)$
   • D) $\text{MgSO}_4$; $\text{Ba}^{2+}(aq) + \text{SO}_4^{2-}(aq) \rightarrow \text{BaSO}_4(s)$
2. 2.

   A chemistry student combines 200.0 mL of 0.150 M calcium chloride, $\text{CaCl}_2(aq)$, with 300.0 mL of 0.100 M sodium phosphate, $\text{Na}_3\text{PO}_4(aq)$, causing a solid precipitate to form. Assuming the solution volumes are additive and the insoluble salt precipitates completely, the resulting mixture is filtered to collect the clear supernatant solution. Based on solubility rules and reaction stoichiometry, what is the correct order of dissolved ion concentrations in the filtered solution from highest to lowest?

   • A) $[\text{Cl}^-] > [\text{Na}^+] > [\text{PO}_4^{3-}] > [\text{Ca}^{2+}]$
   • B) $[\text{Na}^+] > [\text{Cl}^-] > [\text{PO}_4^{3-}] > [\text{Ca}^{2+}]$
   • C) $[\text{Na}^+] > [\text{PO}_4^{3-}] > [\text{Cl}^-] > [\text{Ca}^{2+}]$
   • D) $[\text{Cl}^-] > [\text{Na}^+] > [\text{Ca}^{2+}] > [\text{PO}_4^{3-}]$
3. 3.

   A laboratory student mixes 100 mL of 0.20 M iron(III) nitrate, $\text{Fe(NO}_3)_3(aq)$, with 100 mL of 0.30 M sodium hydroxide, $\text{NaOH}(aq)$, producing an insoluble precipitate. Based on general solubility rules and reaction stoichiometry, which insoluble compound precipitates, and which substance serves as the limiting reactant?

   • A) $\text{NaNO}_3$ precipitates, and $\text{Fe(NO}_3)_3$ is the limiting reactant.
   • B) $\text{Fe(OH)}_3$ precipitates, and $\text{Fe(NO}_3)_3$ is the limiting reactant.
   • C) $\text{Fe(OH)}_3$ precipitates, and $\text{NaOH}$ is the limiting reactant.
   • D) $\text{Fe(OH)}_2$ precipitates, and $\text{NaOH}$ is the limiting reactant.
4. 4.

   A chemist conducts qualitative precipitation tests on separate aliquots of a clear solution containing an unknown divalent metal cation. Adding aqueous sodium chloride or dilute sulfuric acid yields no precipitate in either aliquot, whereas adding aqueous sodium hydroxide produces a pale blue precipitate. Finally, treating another aliquot with aqueous sodium sulfide yields a dark precipitate. Based on solubility rules and these observations, which cation is present in the solution, and what is the net ionic equation for the reaction with sodium hydroxide?

   • A) $\text{Fe}^{2+}$; $\text{Fe}^{2+}(aq) + 2\text{OH}^-(aq) \rightarrow \text{Fe(OH)}_2(s)$
   • B) $\text{Pb}^{2+}$; $\text{Pb}^{2+}(aq) + 2\text{OH}^-(aq) \rightarrow \text{Pb(OH)}_2(s)$
   • C) $\text{Cu}^{2+}$; $\text{Cu}^{2+}(aq) + 2\text{OH}^-(aq) \rightarrow \text{Cu(OH)}_2(s)$
   • D) $\text{Ba}^{2+}$; $\text{Ba}^{2+}(aq) + 2\text{OH}^-(aq) \rightarrow \text{Ba(OH)}_2(s)$
5. 5.

   An environmental chemist analyzes an industrial wastewater sample containing dissolved lead(II) ions, $\text{Pb}^{2+}(aq)$, and barium ions, $\text{Ba}^{2+}(aq)$. To selectively separate the lead(II) ions as a solid precipitate while ensuring that the barium ions remain completely dissolved in solution, the chemist must choose an appropriate sodium salt reagent. Based on solubility rules and reaction stoichiometry, which reagent should be added, and what is the correct net ionic equation for the precipitation process?

   • A) $\text{Na}_2\text{SO}_4(aq)$, with the net ionic equation $\text{Pb}^{2+}(aq) + \text{SO}_4^{2-}(aq) \rightarrow \text{PbSO}_4(s)$
   • B) $\text{Na}_2\text{CO}_3(aq)$, with the net ionic equation $\text{Pb}^{2+}(aq) + \text{CO}_3^{2-}(aq) \rightarrow \text{PbCO}_3(s)$
   • C) $\text{NaI}(aq)$, with the net ionic equation $\text{Pb}^{2+}(aq) + 2\text{NaI}(aq) \rightarrow \text{PbI}_2(s) + 2\text{Na}^+(aq)$
   • D) $\text{NaI}(aq)$, with the net ionic equation $\text{Pb}^{2+}(aq) + 2\text{I}^-(aq) \rightarrow \text{PbI}_2(s)$

Answers and step-by-step solutions appear after you finish the test.