molar mass
- Related Topics:
- mass
- mole
- molecular weight
molar mass, the mass of a substance in grams of one mole of that substance. A mole is a standard scientific unit for measuring large quantities of very small entities, such as atoms, molecules, or other specified particles. The mole designates an extremely large number of units, 6.02214076 × 1023. The molar mass of a substance is given by the molecular weight of the molecule that makes up that substance in atomic mass units (amu), or daltons (Da). For example, a molecule of water is composed of two atoms of hydrogen and one of oxygen. The atomic weight of one atom of hydrogen is 1.008 amu, so that of two atoms is 2.016. The atomic weight of one atom of oxygen is 15.999. Thus, the molecular weight of water is 18.015 amu, and the molar mass of water is 18.015 grams per mole.