Molar mass represents the weight of one mole molecule in g/mol, molecular mass represents the weight of one molecule in amu and relative molar mass represents the weight of a single atom in terms of ununified mass. Molar mass, molecular mass and relative molar mass are differ from each other in terms of the unit they express. Thus, the derived unit for molar mass is kg/mol.

The base SI unit for mass is the kilogram and that for amount of substance is the mole. The relative molecular mass of hydrogen molecule = sum of the relative atomic masses of two atoms of hydrogen. Molar mass, symbol M, is a physical property characteristic of a given substance (chemical element or chemical compound), namely its mass per amount of substance. Solution: Hydrogen molecule represented by H₂. Molar mass of water = 2 *1 + 16 = 18 amu.Įxample: What will be the relative molar mass of the hydrogen molecule. Solution: The formula of the water molecule is H₂O. Molar mass (AB 2 ) = atomic mass (in grams) of A + 2 × atomic mass of B (in grams) Solved ExamplesĮxample: Find the molecular of the water molecule. By adding the atomic weight of the constituent elements in grams we will get the molar mass equation as: It is equal to the sum of the individual atomic mass of each substance (in grams) in the molecule. Molecular mass (AB 2 ) = atomic mass of A + 2 × atomic mass of B Molar Mass By adding the atomic weight of the constituent elements of a molecule we will get molecular weight formula as: It is equal to the sum of the individual atomic mass of each atom in the molecule. Molar Mass Formula and Molecular Mass Formula It is measured in terms of u (unified mass). The relative molecular mass of a substance is the sum of the atomic masses of all the atoms in a molecule of the substance.

For example: The molar mass of water is 18 grams.įor example The molecular mass of water is 18 amu.