Mole conversions (mass, particles, gas volume at STP) Knowledge-Based Practice

Questions

1. 1.

   What is the mass, in grams, of a sample of sulfur trioxide ($\text{SO}_3$) containing $1.505 \times 10^{23}$ molecules? (Avogadro's number = $6.02 \times 10^{23}\text{ mol}^{-1}$; atomic masses: $\text{S} = 32.0\text{ g/mol}$, $\text{O} = 16.0\text{ g/mol}$)

   • A) 10.0 g
   • B) 20.0 g
   • C) 40.0 g
   • D) 80.0 g
2. 2.

   A sample of carbon dioxide gas ($\text{CO}_2$) contains $9.03 \times 10^{23}$ molecules. What volume, in liters, does this gas sample occupy at standard temperature and pressure (STP)? (Avogadro's number = $6.02 \times 10^{23}\text{ mol}^{-1}$; molar volume of an ideal gas at STP = 22.4 L/mol)

   • A) 33.6 L
   • B) 22.4 L
   • C) 14.9 L
   • D) 44.8 L
3. 3.

   What is the mass, in grams, of a sample of ammonia gas ($\text{NH}_3$) that occupies 6.72 L at standard temperature and pressure (STP)? (Molar mass: N = 14.0 g/mol, H = 1.0 g/mol; molar volume of an ideal gas at STP = 22.4 L/mol)

   • A) 114 g
   • B) 4.20 g
   • C) 56.7 g
   • D) 5.10 g
4. 4.

   What volume, in liters, does a sample of oxygen gas ($\text{O}_2$) occupy at standard temperature and pressure (STP) if the sample has a mass of 48.0 g? (Molar mass of $\text{O} = 16.0\text{ g/mol}$; molar volume of an ideal gas at STP = $22.4\text{ L/mol}$)

   • A) 11.2 L
   • B) 22.4 L
   • C) 67.2 L
   • D) 33.6 L
5. 5.

   A sample of dinitrogen monoxide ($\text{N}_2\text{O}$) gas occupies 5.60 L at standard temperature and pressure (STP). What is the total number of atoms contained in this sample? (Assume molar volume at STP = 22.4 L/mol and Avogadro's number = $6.02 \times 10^{23}\ \text{mol}^{-1}$)

   • A) $1.51 \times 10^{23}$
   • B) $4.52 \times 10^{23}$
   • C) $3.01 \times 10^{23}$
   • D) $1.81 \times 10^{24}$

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