kg/mol
kilogram per mole
Molar massexact by definition
The kilogram per mole is the coherent SI unit of molar mass, with a factor of 1 that is exact. It is a thousand times larger than the g/mol figure everyone actually uses, so water is 0.018015 kg/mol. It appears mainly inside SI-consistent equations, such as the ideal gas law written in terms of mass, where mixing g/mol into kg and joules is a reliable source of factor-of-1000 errors.
Watch out: Numerically kg/kmol and g/mol are identical, which is why chemical engineering handbooks working in kilomoles can quote 18.015 for water without changing anything.
| 1 kg/mol | 1,000 g/mol |
Solvers that use molar mass