The molar mass is the mass of one mole of a substance, reported in grams. The molar mass is numerically equal to the formula weight but the units are different (g/mol or amu). The difference between formula weight or formula mass is that when the sum of the atomic weights of the atoms in a molecule is determined, it is expressed as formula mass and the unit is amu. When the mass of a one mole of a compound is determined, it is called molar mass or molecular weight. the unit of molar mass is g/mol.

Determination of molar mass: Use the average atomic mass from periodic table. For example: molar mass of carbon 12.01 g/mol, Hydrogen 1.008 g/mol. Molar mass of a compound is determined using the formula of the compound. Individual molar mass of the elements in a compound is taken and multiplied by its coefficients and added all together.

Example: Determine the molar mass of Glucose: C₆H₁₂O₆

Molar mass C → 6*12.01 = (72.06 g/mol )+

H →(12*1.008= (12.096 g/mol ) +

O→( 6* 16.00)= (96 .00g/mol )

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180.16 g/mol

Below is a picture of 1 mol of different element in grams.