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Foundations of Chemistry

Molar Mass

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

Formula / equation M = m / n
Unit g/mol

In depth

Molar mass is obtained by summing the standard atomic weights of every atom in the formula. It is the conversion factor that turns a weighed mass into a number of moles, making it the single most used quantity in stoichiometric calculation. For elements with several isotopes it is a weighted average.

Examples in the real world

H₂SO₄ has a molar mass of 98.08 g/mol (2 × 1.008 + 32.06 + 4 × 16.00); glucose C₆H₁₂O₆ is 180.16 g/mol.