Precipitation reactions and solubility rules Original Scenario-Based Download PDF

Questions

1. 1.

   On a floating cloud-station skimming the upper atmosphere of Venus, life-support engineers capture planetary carbon by converting it into mineral stone via precipitation. An automated synthesizer combines 250 mL of a 0.40 M calcium chloride, $\text{CaCl}_2\text{(aq)}$, solution with 250 mL of a 0.60 M sodium carbonate, $\text{Na}_2\text{CO}_3\text{(aq)}$, solution to produce insoluble calcium carbonate, $\text{CaCO}_3\text{(s)}$. Given that the molar mass of $\text{CaCO}_3$ is 100.1 g/mol and the reaction proceeds to completion, what is the maximum mass of dry precipitate collected by the filtration unit?

   • A) 25.0 g
   • B) 15.0 g
   • C) 5.0 g
   • D) 10.0 g
2. 2.

   In an orbital crystalline sanctuary, synthetic bone scaffolds are fabricated by blending an aqueous solution of calcium nitrate, $\text{Ca(NO}_3)_2\text{(aq)}$, with an aqueous solution of potassium phosphate, $\text{K}_3\text{PO}_4\text{(aq)}$, precipitating a dense mineral matrix. The sanctuary's synthesis computer requires the precise balanced net ionic equation to track the active ion-consumption rate during crystal growth. Which of the following equations represents the correct balanced net ionic equation for this precipitation process?

   • A) $3\text{Ca}^{2+}\text{(aq)} + 2\text{PO}_4^{3-}\text{(aq)} \rightarrow \text{Ca}_3(\text{PO}_4)_2\text{(s)}$
   • B) $3\text{Ca(NO}_3)_2\text{(aq)} + 2\text{K}_3\text{PO}_4\text{(aq)} \rightarrow \text{Ca}_3(\text{PO}_4)_2\text{(s)} + 6\text{KNO}_3\text{(aq)}$
   • C) $\text{Ca}^{2+}\text{(aq)} + \text{PO}_4^{3-}\text{(aq)} \rightarrow \text{CaPO}_4\text{(s)}$
   • D) $\text{K}^+\text{(aq)} + \text{NO}_3^-\text{(aq)} \rightarrow \text{KNO}_3\text{(s)}$
3. 3.

   Inside a subterranean hydrothermal research facility, an automated sampling manifold processes simulated thermal brine solutions to test mineral recovery methods. The automated system must trigger a precipitation reaction by blending two homogeneous aqueous salt solutions so that a transition-metal solid can be collected. According to general solubility rules, which of the following pairs of aqueous solutions will react to produce an insoluble precipitate when mixed?

   • A) $\text{NH}_4\text{NO}_3\text{(aq)}$ and $\text{KCl(aq)}$
   • B) $\text{NaCH}_3\text{COO(aq)}$ and $\text{CuSO}_4\text{(aq)}$
   • C) $\text{LiBr(aq)}$ and $\text{Zn(NO}_3)_2\text{(aq)}$
   • D) $\text{FeSO}_4\text{(aq)}$ and $\text{KOH(aq)}$
4. 4.

   In a subterranean biodome on an arid exoplanet, an environmental engineer must selectively remove toxic lead(II) ions, $\text{Pb}^{2+}\text{(aq)}$, from an agricultural graywater reservoir that also contains dissolved magnesium ions, $\text{Mg}^{2+}\text{(aq)}$, and sodium ions, $\text{Na}^+\text{(aq)}$. To preserve essential plant nutrients, the engineer requires a treatment solution that precipitates only $\text{Pb}^{2+}$ as an insoluble compound while leaving $\text{Mg}^{2+}$ and $\text{Na}^+$ fully dissolved in the aqueous phase. Based on general solubility rules, which of the following aqueous reagents will successfully precipitate only the lead(II) ions from this mixture?

   • A) Aqueous sodium hydroxide, $\text{NaOH(aq)}$
   • B) Aqueous sodium carbonate, $\text{Na}_2\text{CO}_3\text{(aq)}$
   • C) Aqueous sodium sulfate, $\text{Na}_2\text{SO}_4\text{(aq)}$
   • D) Aqueous sodium phosphate, $\text{Na}_3\text{PO}_4\text{(aq)}$
5. 5.

   An environmental officer aboard an orbital botanical station investigates a dense cloud forming inside a closed irrigation loop when a nutrient stream of aqueous potassium sulfate, $\text{K}_2\text{SO}_4\text{(aq)}$, inadvertently mixes with an emergency sterilizing flush containing aqueous barium nitrate, $\text{Ba(NO}_3)_2\text{(aq)}$. To safely purge the clogged lines, the officer must determine the chemical identity of the solid sediment clogging the valves and the ions that remain freely dissolved. Which of the following correctly identifies the solid precipitate formed and the spectator ions remaining in the solution?

   • A) Precipitate: $\text{KNO}_3\text{(s)}$; Spectator ions: $\text{Ba}^{2+}\text{(aq)}$ and $\text{SO}_4^{2-}\text{(aq)}$
   • B) Precipitate: $\text{BaSO}_4\text{(s)}$; Spectator ions: $\text{K}^+\text{(aq)}$ and $\text{NO}_3^-\text{(aq)}$
   • C) Precipitate: $\text{BaSO}_4\text{(s)}$; Spectator ions: $\text{Ba}^{2+}\text{(aq)}$ and $\text{SO}_4^{2-}\text{(aq)}$
   • D) Precipitate: $\text{K}_2\text{SO}_4\text{(s)}$; Spectator ions: $\text{Ba}^{2+}\text{(aq)}$ and $\text{NO}_3^-\text{(aq)}$