Why is 22.4 liters called the molar volume of a gas?

1 Answer

The Molar Volume of an ideal gas at STP, which we define to be 0^@ "C"0C and "1 atm"1 atm arbitrarily (because we're old-fashioned and stuck in 1982) is "22.411 L/mol"22.411 L/mol.

To calculate this we can use the Ideal gas law of PV=nRTPV=nRT

At STP (Standard Temperature and Pressure), we CHOSE:
P = "1 atm"P=1 atm
V = ?V=?
n = "1 mol"n=1 mol
R = "0.082057 L"cdot"atm/mol"cdot"K"R=0.082057 Latm/molK
"T = 273.15 K"T = 273.15 K

V = (nRT)/PV=nRTP

= (1 cancel("mol")) (0.082057 (cancel("atm")cdot"L")/(cancel("mol")cdotcancel("K")))(273.15cancel("K"))/(1 cancel("atm"))

= "22.411 L"

This is the volume of one mole of ideal gas at STP, in 1982 or before...