A balloon is inflated to 7.0 L of volume at standard temperature and pressure (STP). How many moles of gas does it contain?

• A. 0.16 mol
• B. 0.44 mol
• C. 1.0 mol
• D. 0.31 mol

Answer: (D)

Verified step by step guidance

1. Identify the known conditions: The volume of the gas is 7.0 L, and the gas is at standard temperature and pressure (STP). At STP, the temperature is 0°C (273.15 K) and the pressure is 1 atm.
2. Recall the molar volume of an ideal gas at STP, which is the volume occupied by one mole of gas under these conditions. This value is 22.4 L/mol.
3. Use the relationship between volume and moles at STP, given by the formula: \(\text{moles} = \frac{\text{volume}}{\text{molar volume at STP}}\).
4. Substitute the known values into the formula: \(\text{moles} = \frac{7.0\, \text{L}}{22.4\, \text{L/mol}}\).
5. Calculate the quotient to find the number of moles of gas contained in the balloon.