Formula Mass of a Carbonate
A carbonate is a compound that contains the carbonate ion (CO₃²⁻). To calculate the formula mass (also called formula weight) of a carbonate, the individual atomic masses of all atoms in the compound are added together.
Common Example: Calcium Carbonate (CaCO₃)
To find the formula mass of CaCO₃, add the atomic masses of:
- 1 Calcium (Ca): 40.08 u
- 1 Carbon (C): 12.01 u
- 3 Oxygen (O): 3 × 16.00 u = 48.00 u
Total Formula Mass = 40.08 + 12.01 + 48.00 = 100.09 u
Another Example: Sodium Carbonate (Na₂CO₃)
- 2 Sodium (Na): 2 × 22.99 u = 45.98 u
- 1 Carbon (C): 12.01 u
- 3 Oxygen (O): 3 × 16.00 u = 48.00 u
Total Formula Mass = 45.98 + 12.01 + 48.00 = 105.99 u
General Formula Mass Calculation Steps
- Identify the chemical formula of the carbonate.
- Note the atomic masses of each element (from the periodic table).
- Multiply atomic mass by the number of atoms of each element.
- Add all contributions to get the total formula mass.
Importance
Formula mass is crucial for stoichiometric calculations in chemistry, such as determining the amount of substance in moles or predicting the yield of reactions involving carbonate compounds.