### Definition

Gram molecular mass is the mass in grams of one mole of a molecular substance. Gram molecular mass is the same as molar mass. The only difference is that gram molecular mass specifies the mass unit to be used. Gram molecular mass may be reported in grams or grams per mole (g/mol).

### How to Find Gram Molecular Mass

Use the molecular formula to calculate mass.

- Look up the relative atomic mass of each element in the formula.
- Multiply the subscript after each element symbol (the number of atoms) by that element's atomic mass. If there is no subscript, it means there is only one atom of that element in the molecule.
- Add all of the values together to find the gram molecular mass.

### Example

The molecular mass of N_{2} is 28, so the gram molecular mass of N_{2} is 28 g.