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How to Find Molecular Mass

Steps to Find Molecular Mass of a Compound


Add up atomic masses to obtain molecular mass.

Add up atomic masses to obtain molecular mass.

Lawrence Lawry, Getty Images

The molecular mass is the total mass of a compound. It is equal to the sum of the individual atomic masses of each atom in the molecule. It is easy to find the molecular mass of a compound with these steps.

  1. Determine the molecular formula of the molecule.
  2. Use the periodic table to determine the atomic mass of each element in the molecule.
  3. Multiply each element's atomic mass by the number of atoms of that element in the molecule. This number is represented by the subscript next to the element symbol in the molecular formula.
  4. Add these values together for each different atom in the molecule.
The total will be the molecular mass of the compound.

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