Stoichiometry :  Percent Composition

Percent Composition - The percent composition of a component in a compound is the percent of the total mass of the compound that is due to that component.

To calculate the percent composition of a component in a compound:
  1. Find the molar mass of the compound by adding up the masses of each atom
    in the compound using the periodic table.
  2. Calculate the mass due to the component in the compound you are for which
    you are solving by adding up the mass of these atoms.
  3. Divide the mass due to the component by the total molar mass of the compound
    and multiply by 100.


Example Percent Composition Problem

Calculate the percent composition of carbon in each of the following:

CO2

Molar mass of compound:  

Mass due to carbon:   12.01 g/mol

Percent composition of carbon:  

C6H12O6

Molar mass of compound:  

Mass due to carbon:  

Percent composition of carbon:  

Next:  "Empirical Formulas"