Molecular mass is the mass of one molecule, it differs because of isotopes. It is measured in amu ( atomic mass number) unit. Molar mass is the mass of the substance for the given amount. It has a SI unit of g/mol. In this article, we discuss 7 differences between molar mass and molecular mass.
| Molar mass | Molecular mass |
| It refers to the mass of the mole of the substance | It refers to the mass of the molecules |
| It is known as molecular weight | Determines mass of single-molecule |
| Defined as a mass of Avogadro number of atoms or the molecules or compound | It is defined as the sum of atomic masses of the atoms present in the molecule of the substance |
| Measurement is given to the compounds, atoms, or the molecule | It determines only in molecules |
| It is less accurate than the molecular mass | It is accurate to use in the higher calculations |
| For example, the mass of 1 mole of oxygen is 15.9994g hence the molar mass is 15.9994g/mol | Example: The molecular mass of the Ca(OH)2 is 74 amu. |
| To provide the measurements | To determine the mass of the molecules |
Can you give a real-life example of the difference between molar mass and molecular mass?
Let us take the example of oxygen to understand the differences between molar mass and molecular mass. Oxygen, the gas that we see is present as an O2 molecule, which is a diatomic gas. The molar mass of each oxygen atom will be fixed at 15.9994g/mol. But the molecular mass of the O2 molecule will be 16+16=32 amu.
