Which statement about the molar volume of an ideal gas at STP is true?

Which statement about the molar volume of an ideal gas at STP is true?

• A. 22.4 L per mole
• B. 24.0 L per mole
• C. 18.0 L per mole
• D. 20.0 L per mole

Answer: (A)

At STP, the molar volume follows from the ideal gas law: V = nRT/P. For one mole, using T = 273.15 K, P = 1 atm, and R ≈ 0.0821 L·atm/(mol·K), V = (1)(0.0821)(273.15)/(1) ≈ 22.4 L. So an ideal gas occupies about 22.4 liters per mole at STP. The other values would correspond to different conditions—for example, 24.0 L per mole would be at around 25°C with the same pressure—so 22.4 L is specific to 0°C and 1 atm.

At STP, the molar volume follows from the ideal gas law: V = nRT/P. For one mole, using T = 273.15 K, P = 1 atm, and R ≈ 0.0821 L·atm/(mol·K), V = (1)(0.0821)(273.15)/(1) ≈ 22.4 L. So an ideal gas occupies about 22.4 liters per mole at STP. The other values would correspond to different conditions—for example, 24.0 L per mole would be at around 25°C with the same pressure—so 22.4 L is specific to 0°C and 1 atm.