Question

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

Answer 1

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

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

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

`V = (nRT)/P`

`= (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...