Mass Percent Calculator
Enter the chemical formula using standard notation. Subscripts are automatically detected.
Percent Composition Results
| Element | Atoms | Atomic Mass | Total Mass | Percent |
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What is Percent Composition?
Percent composition, also known as mass percent or weight percent, is the percentage by mass of each element in a compound. It represents the proportion of a particular element’s mass relative to the total mass of the compound.
This concept is fundamental in chemistry for:
- Determining empirical formulas from experimental data
- Calculating the mass of elements in a given sample of a compound
- Understanding the composition of chemical substances
- Quality control in chemical manufacturing
Example: Water (H₂O)
Water consists of hydrogen and oxygen. To calculate the percent composition:
Molar mass of H₂O = (2 × 1.008) + 16.00 = 18.016 g/mol
Percent hydrogen = (2.016 / 18.016) × 100% = 11.19%
Percent oxygen = (16.00 / 18.016) × 100% = 88.81%