Molecular mass | Formula unit mass |
It is the sum of the masses of all the atoms in a molecule. [0.5 Marks] |
It is the sum of the masses of all atoms in a formula unit of a compound. [0.5 Marks] |
For example: Water (H2O) has molecular mass of 18 u. [0.5 Marks] |
For example: Sodium chloride (NaCl) has formula unit mass of 58.5 u. [0.5 Marks] |