Molar mass

Definition

The mass of one mole of a substance, numerically equal to its atomic or molecular mass in grams per mole.

For water it is computed as two times hydrogen (1.008) plus one oxygen (15.999), giving 18.015 g/mol. It is the conversion factor that turns grams into moles, a required step before counting molecules. Molecular mass for a compound is just the sum of the molar masses of its constituent atoms, as with NaCl at 58.44 g/mol.

Related concepts

Dimensional analysis · Atomic mass and atomic weight · Mole

---

Part of The Blueprint of Water · 📏 measurement