The mass of one mole of particles is called?

• A. Molecular mass
• B. Molar mass
• C. Relative atomic mass
• D. Formula mass

Answer: (B)

Mass per mole of particles is called molar mass, and it is measured in grams per mole. This quantity bridges the tiny world of atomic or molecular masses (usually given in atomic mass units, or amu, per particle) with the everyday amount of substance we handle in the lab (moles). The numeric value of a substance’s molar mass in g/mol matches its molecular (or formula unit) mass in amu, so a molecule with a mass of 18.015 amu has a molar mass of 18.015 g/mol. For example, water’s molecular mass is about 18.015 amu per molecule, so its molar mass is 18.015 g/mol. Relative atomic mass is a dimensionless number defined relative to carbon-12, and formula mass is the mass of a single formula unit, given in amu. The crucial idea is that molar mass tells you how much mass 1 mole of that substance weighs, linking amount of substance to mass.