Molar mass Original Scenario-Based Practice

Questions

1. 1.

   In an orbital laboratory testing zero-gravity fire suppression, researchers evaluate a volatile extinguishing vapor using two identical rigid chambers under identical temperature and pressure conditions. Chamber 1 holds 1.60 g of pure sulfur dioxide gas ($\text{SO}_2$), whereas Chamber 2 holds 2.50 g of the vaporized fire suppressant. Given that the molar mass of sulfur dioxide is 64.0 g/mol, what is the molar mass of the unknown fire suppressant?

   • A) 41.0 g/mol
   • B) 50.0 g/mol
   • C) 80.0 g/mol
   • D) 100 g/mol
2. 2.

   A subterranean research outpost on a volcanic moon synthesizes a heat-resistant semiconductor crystal with the formula $\text{M}_2\text{S}_3$. During thermal characterization, a chemist determines that a 0.125 mol sample of this pure compound has a mass of exactly 26.0 g. Given that the molar mass of sulfur is 32.0 g/mol, what is the molar mass of the unknown element M?

   • A) 112 g/mol
   • B) 88.0 g/mol
   • C) 44.0 g/mol
   • D) 56.0 g/mol
3. 3.

   An atmospheric skimming drone exploring the dense cloud layers of an alien planet captures a pure specimen of an unidentified vapor. Diagnostic instruments establish that a sample containing exactly $1.505 \times 10^{22}$ molecules of this gas has a mass of 1.60 g. Given that Avogadro's constant is $6.02 \times 10^{23}\text{ mol}^{-1}$, what is the molar mass of the collected vapor?

   • A) 64.0 g/mol
   • B) 32.0 g/mol
   • C) 48.0 g/mol
   • D) 128 g/mol
4. 4.

   In a subterranean biome sanctuary, bioengineers synthesize an artificial oxygen-carrying protein named neocruorin to sustain researchers in low-oxygen caves. Quantitative elemental analysis indicates that each molecule of pure neocruorin contains exactly two iron atoms, which together account for 0.186% of the protein's total mass. Given that the molar mass of iron is 55.8 g/mol, what is the molar mass of neocruorin?

   • A) 30,000 g/mol
   • B) 600 g/mol
   • C) 60,000 g/mol
   • D) 120,000 g/mol
5. 5.

   During a deep-space voyage, an orbital biosphere module detects an unexpected gas accumulation in an auxiliary storage tank. The automated diagnostic unit measures that a 0.750 mol sample of this pure gaseous compound has a mass of exactly 33.0 g. Based on the vessel's elemental inventory, the gas is known to be a common binary oxide of carbon or nitrogen. Which substance was trapped in the storage tank? (Atomic masses: C = 12.0 g/mol, N = 14.0 g/mol, O = 16.0 g/mol)

   • A) $\text{CO}$
   • B) $\text{NO}$
   • C) $\text{NO}_2$
   • D) $\text{CO}_2$

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