How is the percentage composition of a compound determined from its formula ?

The percentage composition of a compound means the mass percentage of each element present in the compound. The mass percentage of each element can be determined from the molecular or empirical formula of the compound as follows:

Step1: write the molecular or empirical formula of the compound.

Step 2: write the name. Number of atoms and the total mass of each element present in one molecule of the compound.

Step 3 : Obtain the molecular mass, or formula mass of the compound by adding the masses of all the elements present in it.

Step 4: Calculate the mass percentage of each element by using the relationship.

Mass percentage of an element= ^{Total mass of the element in one molecule of the compound} / _{Molecular mass of the compound} × 100