Mass–mass calculations Original Scenario-Based Download PDF

Questions

1. 1.

   To keep an aerial observation fleet afloat above the turbulent clouds of the gas giant Zephyrus, the synthesis rig of an orbital skydock processes methane with high-temperature steam according to the balanced equation $\text{CH}_4(g) + \text{H}_2\text{O}(g) \rightarrow \text{CO}(g) + 3\text{H}_2(g)$. If the catalytic reformer completely consumes 48.0 g of methane in the presence of excess steam, what mass of hydrogen gas ($\text{H}_2$) is generated? (Molar masses: C = 12.0 g/mol, H = 1.0 g/mol, O = 16.0 g/mol)

   • A) 6.0 g
   • B) 9.0 g
   • C) 27.0 g
   • D) 18.0 g
2. 2.

   A deep-trench research pod stranded beneath an extraterrestrial ice shelf activates its emergency chemical breathing system, which converts sodium peroxide and water vapor into oxygen according to the balanced equation $2\text{Na}_2\text{O}_2(s) + 2\text{H}_2\text{O}(l) \rightarrow 4\text{NaOH}(aq) + \text{O}_2(g)$. If the pod's regeneration canister fully consumes 312 g of $\text{Na}_2\text{O}_2$ in the presence of excess water, what mass of oxygen gas ($\text{O}_2$) is liberated? (Molar masses: Na = 23.0 g/mol, O = 16.0 g/mol, H = 1.0 g/mol)

   • A) 64.0 g
   • B) 128 g
   • C) 256 g
   • D) 32.0 g
3. 3.

   An automated asteroid-mining vessel refines structural plating by reducing liquid titanium(IV) chloride with molten magnesium according to the balanced equation $\text{TiCl}_4(l) + 2\text{Mg}(l) \rightarrow \text{Ti}(s) + 2\text{MgCl}_2(s)$. If the vessel's reactor completely consumes 380 g of $\text{TiCl}_4$ in the presence of excess magnesium, what mass of pure titanium metal is harvested? (Molar masses: Ti = 48 g/mol, Cl = 35.5 g/mol, Mg = 24 g/mol)

   • A) 48 g
   • B) 190 g
   • C) 192 g
   • D) 96 g
4. 4.

   A life-support scrub drone stationed inside the subterranean lunar colony Vesta is deployed to clear carbon dioxide from an auxiliary chamber according to the balanced equation $2\text{LiOH}(s) + \text{CO}_2(g) \rightarrow \text{Li}_2\text{CO}_3(s) + \text{H}_2\text{O}(l)$. If the scrubber completely consumes 120 g of solid lithium hydroxide in the reaction, what mass of carbon dioxide gas is absorbed from the chamber? (Molar masses: Li = 7.0 g/mol, C = 12.0 g/mol, O = 16.0 g/mol, H = 1.0 g/mol)

   • A) 220 g
   • B) 110 g
   • C) 55.0 g
   • D) 88.0 g
5. 5.

   A deep-space repair crew aboard the vessel Starlight must seal an exterior hull breach using an emergency thermite weld described by the balanced equation: 2Al(s) + Fe2O3(s) → Al2O3(s) + 2Fe(l). If the automated dispensing unit fully consumes 81.0 g of aluminum powder in the presence of excess iron(III) oxide, what mass of molten iron is produced? (Molar masses: Al = 27.0 g/mol, Fe = 56.0 g/mol)

   • A) 168 g
   • B) 84.0 g
   • C) 336 g
   • D) 81.0 g