Balancing equations Original Scenario-Based Practice

Questions

1. 1.

   In a subterranean bio-vault buried beneath an irradiated desert, an automated life-support unit produces chlorine gas for atmospheric sanitation by reacting solid manganese dioxide with hydrochloric acid. The process follows the unbalanced equation $\text{MnO}_2 + \text{HCl} \rightarrow \text{MnCl}_2 + \text{Cl}_2 + \text{H}_2\text{O}$. When this equation is balanced using the lowest whole-number coefficients, what is the stoichiometric coefficient of hydrochloric acid ($\text{HCl}$)?

   • A) 1
   • B) 2
   • C) 3
   • D) 4
2. 2.

   Inside an artificial biosphere deep within a hollowed asteroid, atmospheric scrubbers capture phosphorus vapor and convert it into solid tetraphosphorus decoxide ($\text{P}_4\text{O}_{10}$). To produce liquid phosphoric acid ($\text{H}_3\text{PO}_4$) for hydro-agricultural bays, the compound is reacted with steam ($\text{H}_2\text{O}$) according to the unbalanced equation $\text{P}_4\text{O}_{10} + \text{H}_2\text{O} \rightarrow \text{H}_3\text{PO}_4$. When this chemical equation is balanced using the lowest whole-number coefficients, what is the stoichiometric coefficient of $\text{H}_2\text{O}$?

   • A) 3
   • B) 6
   • C) 4
   • D) 12
3. 3.

   Inside a subterranean foundry beneath the crystalline dunes of Mars, automated smelting crawlers process excavated pyrite ($\text{FeS}_2$) by roasting it with oxygen gas ($\text{O}_2$) to produce solid iron(III) oxide ($\text{Fe}_2\text{O}_3$) and sulfur dioxide gas ($\text{SO}_2$). When this chemical equation is balanced using the lowest whole-number coefficients, what is the sum of all the stoichiometric coefficients of the reactants and products?

   • A) 25
   • B) 21
   • C) 19
   • D) 13
4. 4.

   Deep beneath the ice shelf of an uncharted moon, a robotic research habitat synthesizes fuel by reacting solid aluminum carbide ($\text{Al}_4\text{C}_3$) with liquid water ($\text{H}_2\text{O}$) to yield solid aluminum hydroxide ($\text{Al(OH)}_3$) and gaseous methane ($\text{CH}_4$). When this chemical equation is balanced using the lowest whole-number coefficients, what are the stoichiometric coefficients of $\text{Al}_4\text{C}_3$, $\text{H}_2\text{O}$, $\text{Al(OH)}_3$, and $\text{CH}_4$, respectively?

   • A) 1, 12, 4, 3
   • B) 1, 6, 4, 3
   • C) 2, 12, 4, 6
   • D) 1, 12, 2, 3
5. 5.

   To neutralize toxic thruster propellant vapors inside an orbital habitat, life-support engineers vent dinitrogen tetroxide ($\text{N}_2\text{O}_4$) into an emergency scrubber containing hydrazine ($\text{N}_2\text{H}_4$), producing inert nitrogen gas ($\text{N}_2$) and water vapor ($\text{H}_2\text{O}$). When this chemical equation is balanced using the lowest whole-number coefficients, what are the stoichiometric coefficients of $\text{N}_2\text{O}_4$, $\text{N}_2\text{H}_4$, $\text{N}_2$, and $\text{H}_2\text{O}$, respectively?

   • A) 1, 2, 3, 4
   • B) 1, 1, 2, 2
   • C) 2, 1, 3, 2
   • D) 1, 4, 3, 8

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