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Percent Composition Calculator
Calculate the percentage composition of elements in a compound.
Composition Calculator
What is Percent Composition?
Percent composition is the percentage by mass of each element in a compound. It tells you what fraction of the total molecular mass each element contributes.
Formula
% Element = (mass of element / total molar mass) × 100
Example: H₂O
- • H: 2 × 1.008 = 2.016 g/mol
- • O: 1 × 16.00 = 16.00 g/mol
- • Total = 18.016 g/mol
- • % H = (2.016 / 18.016) × 100 = 11.19%
- • % O = (16.00 / 18.016) × 100 = 88.81%
💡 Tips
- • All percentages should add up to 100%
- • Use accurate atomic masses from the periodic table
- • This is used to determine empirical and molecular formulas