cubic foot per pound-mole
Molar volumeexact by definition
The cubic foot per pound-mole is the US process-engineering unit of molar volume, equal to 6.242796e-5 m³/mol. The relation is exact by definition, from the cubic foot of exactly 0.028316846592 m³ and the pound-mole of exactly 453.59237 mol, though the decimal shown is a rounding of that exact ratio. One pound-mole of an ideal gas occupies about 359 ft³ at 32 °F and one atmosphere, and 379.5 ft³ at 60 °F and 14.696 psia.
Watch out: A pound-mole is not a mole. It is 453.59237 mol, the number of entities whose mass in pounds equals the relative molecular mass. Handbooks mix lb-mol and mol on facing pages, and the factor between them is the same 453.59 that separates the pound from the gram.
| 1 ft³/lb-mol | 0.062427961 L/mol |
The 379.5 scf per lb-mol figure at 60 °F is the basis of natural gas accounting in North America, where gas is bought and sold by the standard cubic foot and converted to a molar or energy basis at the meter.