All you need to do is to follow these 3 steps.
1. Estimate the number of each kind of atom present in the compound using the chemical formula in order to determine the molar mass of the molecule.
- Divide each element's atomic weight (found in the periodic table) by the quantity of that element's atoms in the compound.
- Add up the total, then follow the number with the units of grams/mole.
eg. Water
- 2 hydrogen atoms and 1 oxygen atom make up the chemical formula H20.
- H- 1's atomic weight
- O-16's atomic weight
- Number of H atoms overall in formula 2
- Number of O atoms overall in formula 1
- The molar mass will thus be as follows: H 2 x 1= 2 O 1 x 16= 16 16+2= 18
- Water's molar mass is 18 g/mol as a result.