Percent Composition of a compound is determined easily. The first thing you need to do is to determine the Molar Mass. Once the Molar Mass is determined, divide the total mass of each element by the Molar Mass and then multiply that result by 100, to get percent.
For Na2SO4, you would determine the following Percent Composition.
| Compound | Molar Mass | %Na | %S | %O |
|---|---|---|---|---|
| Na2SO4 | 142.0 g/mol | 32.4% Na | 22.5% S | 45.1% O |
Copyright © Dr. Donald L. Robertson (Modified: 10/10/2010)