lb/lb-mol
pound per pound-mole
Molar massexact by definition
The pound per pound-mole is exactly 10⁻³ kg/mol, so the numerical value is identical to grams per mole: methane is 16.04 lb/lb-mol and 16.04 g/mol. US process engineering keeps this unit precisely because the number never changes.
| 1 lb/lb-mol | 1 g/mol |
Where the unit came from
The pound-mole is defined as the amount whose mass in pounds equals the molecular weight, which forces the identity. It is the one place in imperial engineering where nobody has to convert anything, and it survives for that reason alone.
Solvers that use molar mass