Ionic and net ionic equations Original Scenario-Based Download PDF

Questions

1. 1.

   Aboard an automated bio-regenerative life-support satellite, agricultural bots neutralize organic acid runoff by treating aqueous acetic acid, $\text{CH}_3\text{COOH(aq)}$, with an aqueous solution of potassium hydroxide, $\text{KOH(aq)}$. The process yields dissolved potassium acetate, $\text{CH}_3\text{COOK(aq)}$, and liquid water. Because acetic acid is a weak acid, it remains predominantly intact as molecules rather than dissociating completely into ions. Which of the following represents the correct balanced net ionic equation for this neutralization reaction?

   • A) $\text{CH}_3\text{COOH(aq)} + \text{OH}^-\text{(aq)} \rightarrow \text{CH}_3\text{COO}^-\text{(aq)} + \text{H}_2\text{O(l)}$
   • B) $\text{H}^+\text{(aq)} + \text{OH}^-\text{(aq)} \rightarrow \text{H}_2\text{O(l)}$
   • C) $\text{CH}_3\text{COOH(aq)} + \text{K}^+\text{(aq)} + \text{OH}^-\text{(aq)} \rightarrow \text{CH}_3\text{COOK(aq)} + \text{H}_2\text{O(l)}$
   • D) $\text{K}^+\text{(aq)} + \text{CH}_3\text{COO}^-\text{(aq)} \rightarrow \text{CH}_3\text{COOK(aq)}$
2. 2.

   Inside an atmospheric bio-dome on an arid moon, environmental systems engineers scrub excess acidic vapors by reacting aqueous hydrobromic acid, $\text{HBr(aq)}$, with an aqueous reservoir of potassium carbonate, $\text{K}_2\text{CO}_3\text{(aq)}$. The reaction neutralizes the acid while producing carbon dioxide gas, liquid water, and soluble potassium bromide, $\text{KBr(aq)}$. Which of the following represents the correct balanced net ionic equation for this gas-evolution reaction?

   • A) $\text{K}_2\text{CO}_3\text{(aq)} + 2\text{HBr(aq)} \rightarrow 2\text{KBr(aq)} + \text{H}_2\text{O(l)} + \text{CO}_2\text{(g)}$
   • B) $\text{CO}_3^{2-}\text{(aq)} + 2\text{H}^+\text{(aq)} \rightarrow \text{H}_2\text{O(l)} + \text{CO}_2\text{(g)}$
   • C) $\text{K}_2\text{CO}_3\text{(aq)} + 2\text{H}^+\text{(aq)} \rightarrow 2\text{K}^+\text{(aq)} + \text{H}_2\text{O(l)} + \text{CO}_2\text{(g)}$
   • D) $2\text{K}^+\text{(aq)} + 2\text{Br}^-\text{(aq)} \rightarrow 2\text{KBr(aq)}$
3. 3.

   During an archaeological expedition to an oceanic exoplanet, exploration geochemists use an aqueous solution of nitric acid, $\text{HNO}_3\text{(aq)}$, to dissolve crusts of insoluble solid magnesium hydroxide, $\text{Mg(OH)}_2\text{(s)}$, fouling the hull of a submerged research vessel. The reaction cleanly clears the mineral deposits, yielding soluble magnesium nitrate, $\text{Mg(NO}_3)_2\text{(aq)}$, and liquid water. Which of the following represents the correct balanced net ionic equation for this reaction?

   • A) $\text{H}^+\text{(aq)} + \text{OH}^-\text{(aq)} \rightarrow \text{H}_2\text{O(l)}$
   • B) $\text{Mg(OH)}_2\text{(s)} + 2\text{H}^+\text{(aq)} \rightarrow \text{Mg}^{2+}\text{(aq)} + 2\text{H}_2\text{O(l)}$
   • C) $\text{Mg}^{2+}\text{(aq)} + 2\text{OH}^-\text{(aq)} + 2\text{H}^+\text{(aq)} \rightarrow \text{Mg}^{2+}\text{(aq)} + 2\text{H}_2\text{O(l)}$
   • D) $\text{Mg(OH)}_2\text{(s)} + 2\text{H}^+\text{(aq)} + 2\text{NO}_3^-\text{(aq)} \rightarrow \text{Mg}^{2+}\text{(aq)} + 2\text{NO}_3^-\text{(aq)} + 2\text{H}_2\text{O(l)}$
4. 4.

   To neutralize an accidental spill of aqueous perchloric acid, $\text{HClO}_4\text{(aq)}$, inside a floating atmospheric laboratory drifting through the upper clouds of Venus, autonomous drones dispense an aqueous solution of barium hydroxide, $\text{Ba(OH)}_2\text{(aq)}$. The resulting rapid neutralization reaction forms soluble barium perchlorate, $\text{Ba(ClO}_4)_2\text{(aq)}$, and liquid water. Which of the following lists all the spectator ions that remain dissolved and unchanged, and therefore cancel out when writing the net ionic equation for this reaction?

   • A) $\text{H}^+\text{(aq)}$ and $\text{OH}^-\text{(aq)}$
   • B) $\text{Ba}^{2+}\text{(aq)}$ and $\text{OH}^-\text{(aq)}$
   • C) $\text{H}^+\text{(aq)}$ and $\text{ClO}_4^-\text{(aq)}$
   • D) $\text{Ba}^{2+}\text{(aq)}$ and $\text{ClO}_4^-\text{(aq)}$
5. 5.

   In an orbital laboratory aboard an interstellar research station, a materials chemist synthesizes a radiation-shielding pigment by mixing an aqueous solution of cobalt(II) nitrate, $\text{Co(NO}_3)_2\text{(aq)}$, with an aqueous solution of sodium phosphate, $\text{Na}_3\text{PO}_4\text{(aq)}$. The reaction instantly produces a dense violet precipitate of cobalt(II) phosphate, $\text{Co}_3(\text{PO}_4)_2\text{(s)}$, suspended in an aqueous solution of sodium nitrate. Which of the following represents the correct balanced net ionic equation for this reaction?

   • A) $3\text{Co}^{2+}\text{(aq)} + 2\text{PO}_4^{3-}\text{(aq)} \rightarrow \text{Co}_3(\text{PO}_4)_2\text{(s)}$
   • B) $\text{Co}^{2+}\text{(aq)} + \text{PO}_4^{3-}\text{(aq)} \rightarrow \text{CoPO}_4\text{(s)}$
   • C) $3\text{Co}^{2+}\text{(aq)} + 6\text{NO}_3^-\text{(aq)} + 6\text{Na}^+\text{(aq)} + 2\text{PO}_4^{3-}\text{(aq)} \rightarrow \text{Co}_3(\text{PO}_4)_2\text{(s)} + 6\text{Na}^+\text{(aq)} + 6\text{NO}_3^-\text{(aq)}$
   • D) $\text{Na}^+\text{(aq)} + \text{NO}_3^-\text{(aq)} \rightarrow \text{NaNO}_3\text{(s)}$