The mass of a substance is the mass per mole of its entities, where the term entities can describe

The molar mass of a substance is the mass per mole of its entities, where the term entities can describe atoms, molecules, ions or formula units.

Explanation:

Molar mass is the mass of any compound divided by mole. Means, if any chemical is given a specific molar mass it means this mass is being given by 6.022 * 10²³ entities of that chemical.

The molar mass of any compound is calculated by adding up the atomic masses of all atoms present in that chemical.

Example:

Molar Mass of H₂ = 1.008 + 1.008 = 2.016 g/mol

Molar Mass of NaOH = 23 + 16 + 1 = 40 g/mol

Molar Mass of HCl = 1 + 35.5 = 36.5 g/mol