What is the mass (in grams) of 5.00 L of O₂ gas at standard temperature and pressure (STP)?

• A. 7.14 g
• B. 22.4 g
• C. 32.0 g
• D. 16.0 g

Answer: (A)

Verified step by step guidance

1. Identify the conditions given: volume of oxygen gas (O\_2) is 5.00 L at standard temperature and pressure (STP). Recall that STP means a temperature of 0°C (273 K) and a pressure of 1 atm.
2. Use the molar volume of a gas at STP, which is 22.4 L/mol. This means 1 mole of any ideal gas occupies 22.4 liters at STP.
3. Calculate the number of moles of O\_2 gas using the formula: \(\text{moles} = \frac{\text{volume of gas}}{\text{molar volume at STP}} = \frac{5.00\, \text{L}}{22.4\, \text{L/mol}}\).
4. Find the molar mass of oxygen gas (O\_2). Since each oxygen atom has an atomic mass of approximately 16.0 g/mol, the molar mass of O\_2 is \$2 \times 16.0 = 32.0$ g/mol.
5. Calculate the mass of the oxygen gas by multiplying the number of moles by the molar mass: \(\text{mass} = \text{moles} \times 32.0\, \text{g/mol}\).