Percent composition Original Scenario-Based Practice

Questions

1. 1.

   A cybernetic bio-fabrication facility on an orbital research station manufactures synthetic bone scaffolds to repair astronaut skeletal trauma caused by prolonged microgravity. The regenerative matrix relies on high-purity tricalcium phosphate, $\text{Ca}_3(\text{PO}_4)_2$, as its mineral foundation. Given the atomic masses $\text{Ca} = 40.08\text{ g/mol}$, $\text{P} = 30.97\text{ g/mol}$, and $\text{O} = 16.00\text{ g/mol}$, what is the percent composition by mass of phosphorus in pure $\text{Ca}_3(\text{PO}_4)_2$?

   • A) 9.98%
   • B) 38.76%
   • C) 19.97%
   • D) 28.78%
2. 2.

   Deep within a dormant geothermal energy vault, engineers discover a canister of crystalline stibnite, chemically identified as pure antimony trisulfide, $\text{Sb}_2\text{S}_3$, intended for high-efficiency thermoelectric generators. To ensure the harvested compound is suitable for semiconductor fabrication, the technical crew must determine the mass proportion of sulfur in the crystalline matrix. Given the atomic masses of antimony ($\text{Sb} = 121.76\text{ g/mol}$) and sulfur ($\text{S} = 32.06\text{ g/mol}$), what is the percent composition by mass of sulfur in pure $\text{Sb}_2\text{S}_3$?

   • A) 71.69%
   • B) 60.00%
   • C) 28.31%
   • D) 39.49%
3. 3.

   An automated life-support habitat on a Jovian moon synthesizes urea, $\text{CO}(\text{NH}_2)_2$, from metabolic carbon dioxide and reclaimed ammonia to produce high-density nitrogen fertilizer for vertical hydroponic aerogardens. To verify the purity of the synthesized batch, technicians analyze the mass fraction of nitrogen delivered to the botanical beds. Given atomic masses of C = 12.01 g/mol, O = 16.00 g/mol, N = 14.01 g/mol, and H = 1.01 g/mol, what is the percent composition by mass of nitrogen in pure urea?

   • A) 23.32%
   • B) 26.64%
   • C) 46.65%
   • D) 19.99%
4. 4.

   Automated mining drones deployed on a desolate crystalline exoplanet harvest corundum-rich crust to extract elemental aluminium for orbital communication arrays. The automated refinery processes pure aluminium oxide, Al₂O₃, to isolate the metal through high-energy electrochemical reduction. Given the atomic masses of Al = 26.98 g/mol and O = 16.00 g/mol, what is the percent composition by mass of aluminium in this compound?

   • A) 26.46%
   • B) 47.08%
   • C) 52.92%
   • D) 62.77%
5. 5.

   During an expedition to an uncharted subterranean cavern, planetary geologists recover a luminescent crystalline salt determined to be cobalt(II) nitrate hexahydrate, $\text{Co}(\text{NO}_3)_2 \cdot 6\text{H}_2\text{O}$. To calibrate a solar thermal extractor that utilizes the compound's structural water, the team must determine the percent composition by mass of water in the crystal. Given the atomic masses $\text{Co} = 58.93\text{ g/mol}$, $\text{N} = 14.01\text{ g/mol}$, $\text{O} = 16.00\text{ g/mol}$, and $\text{H} = 1.01\text{ g/mol}$, what is the mass percentage of water in this hydrated compound?

   • A) 37.15%
   • B) 6.19%
   • C) 59.10%
   • D) 62.85%

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