Mole conversions (mass, particles, gas volume at STP) Transitional Reasoning Practice

Questions

1. 1.

   A rigid laboratory chamber contains a sample of pure carbon dioxide ($\text{CO}_2$) gas occupying 5.60 L at standard temperature and pressure (STP). To adjust the contents for an experiment, a chemist injects an additional quantity of pure $\text{CO}_2$ gas into the chamber until the total number of oxygen atoms reaches $4.515 \times 10^{23}$. Given that the molar volume of an ideal gas at STP is 22.4 L/mol, Avogadro's number is $6.02 \times 10^{23}\text{ mol}^{-1}$, and atomic masses are $\text{C} = 12.0\text{ g/mol}$ and $\text{O} = 16.0\text{ g/mol}$, what mass of carbon dioxide was added to the chamber?

   • A) 11.0 g
   • B) 5.50 g
   • C) 16.5 g
   • D) 22.0 g
2. 2.

   A gas cylinder contains a sample of pure dinitrogen monoxide ($\text{N}_2\text{O}$) gas occupying 3.36 L at standard temperature and pressure (STP). After a portion of the gas is discharged for a laboratory procedure, the remaining gas inside the cylinder has a mass of 4.40 g. Given that the molar volume of an ideal gas at STP is 22.4 L/mol, Avogadro's number is $6.02 \times 10^{23}\text{ mol}^{-1}$, and atomic masses are $\text{N} = 14.0\text{ g/mol}$ and $\text{O} = 16.0\text{ g/mol}$, how many molecules of $\text{N}_2\text{O}$ were discharged?

   • A) $9.03 \times 10^{22}$
   • B) $6.02 \times 10^{22}$
   • C) $3.01 \times 10^{22}$
   • D) $1.51 \times 10^{22}$
3. 3.

   An analytical chemist investigates an unknown gaseous oxide of sulfur with the chemical formula $\text{SO}_x$. At standard temperature and pressure (STP), a 5.60 L sample of this pure gas has a mass of 20.0 g. Given that Avogadro's number is $6.02 \times 10^{23}\text{ mol}^{-1}$, the molar volume of an ideal gas at STP is 22.4 L/mol, and atomic masses are $\text{S} = 32.0\text{ g/mol}$ and $\text{O} = 16.0\text{ g/mol}$, how many total oxygen atoms are present in a 32.0 g sample of this compound?

   • A) $2.408 \times 10^{23}$
   • B) $4.816 \times 10^{23}$
   • C) $9.632 \times 10^{23}$
   • D) $7.224 \times 10^{23}$
4. 4.

   A sealed container holds a gaseous mixture consisting of 4.40 g of carbon dioxide ($\text{CO}_2$) and an unknown quantity of oxygen gas ($\text{O}_2$). Quantitative spectroscopic analysis determines that the entire mixture contains a total of $3.612 \times 10^{23}$ oxygen atoms. Given that the molar volume of an ideal gas at standard temperature and pressure (STP) is 22.4 L/mol, Avogadro's number is $6.02 \times 10^{23}\text{ mol}^{-1}$, and atomic masses are $\text{C} = 12.0\text{ g/mol}$ and $\text{O} = 16.0\text{ g/mol}$, what volume does the oxygen gas occupy at STP?

   • A) 2.24 L
   • B) 3.36 L
   • C) 4.48 L
   • D) 8.96 L
5. 5.

   A research cylinder contains 5.60 L of pure methane gas ($\text{CH}_4$) measured at standard temperature and pressure (STP). A chemist needs to prepare a sample of water vapor ($\text{H}_2\text{O}$) that contains the exact same total number of hydrogen atoms as present in this methane sample. Given that the molar volume of an ideal gas at STP is 22.4 L/mol and atomic masses are $\text{H} = 1.0\text{ g/mol}$, $\text{C} = 12.0\text{ g/mol}$, and $\text{O} = 16.0\text{ g/mol}$, what mass of water vapor must be measured?

   • A) 4.50 g
   • B) 36.0 g
   • C) 9.00 g
   • D) 18.0 g

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