How to calculate molecular mass?
- Determine the molecular formula of the compound.
- Use the periodic table to determine the atomic mass of each element in the molecule.
- Multiply the atomic mass of each element by the number of molecules.
- Finally, add them all up!
Example: Molecular Mass of Water H2O
|ELEMENT||ATOMIC MASS||NUMBER||TOTAL ATOMIC MASS|
Molecular mass of water
= 18.0105 amu
Molecular Mass can also be expressed as a Mole (g/mol)
Mass of Water
Expressed as a mole: 18.0105 g/mol
Expressed as molecular mass: 18.0105 amu
If you see molecular mass expressed in AMU, don’t worry! AMU and g/mol are equivalent to each other.