If a person inhales 1.5 L of oxygen gas (O_2) at standard temperature and pressure (STP), what is the mass (in grams) of oxygen present in their lungs? (Molar mass of O_2 = 32.00 g/mol; 1 mol of gas at STP occupies 22.4 L)

• A. 2.14 g
• B. 0.96 g
• C. 1.50 g
• D. 3.20 g

Answer: (A)

Verified step by step guidance

1. Identify the given information: volume of oxygen gas (V) = 1.5 L, molar volume at STP = 22.4 L/mol, and molar mass of O_2 = 32.00 g/mol.
2. Calculate the number of moles of oxygen gas using the formula: \(\text{moles} = \frac{V}{\text{molar volume}} = \frac{1.5\, \text{L}}{22.4\, \text{L/mol}}\).
3. Use the number of moles to find the mass of oxygen by multiplying by the molar mass: \(\text{mass} = \text{moles} \times 32.00\, \text{g/mol}\).
4. Set up the calculation carefully to ensure units cancel properly, leaving the mass in grams.
5. Interpret the result as the mass of oxygen gas inhaled at STP without performing the final arithmetic.