Percent Composition Calculator
Determine the percentage mass of each element in a given chemical formula.
Calculation Parameters
Specify your chemical inputs.
Calculated Result
Expert Tip
Double check molecular weights and balance equations to ensure stoichiometric ratios are correct.
How this Calculator Works
This calculator determines the mass percentage of each element in a given chemical compound. Enter a valid formula in the input field below:
- Chemical Formula: A compound formula such as H2O or CO2 (Default: H2O)
The results are computed instantly and updated in the results panel on the right.
Formula & Methodology
Where:
- Mass of Element in 1 mole: Element atomic weight multiplied by its quantity.
- Total Molar Mass: Molar mass of the entire chemical compound.
Step-by-Step Calculation Example
To calculate the percent composition of water ($H_2O$, molar mass ≈ 18.015 g/mol) manually, follow these steps:
- Identify the input parameters. For example:
- Formula = H2O
- Total Molar Mass = 18.015 g/mol
- Total Mass of Hydrogen (H) = 2.016 g/mol
- Total Mass of Oxygen (O) = 15.999 g/mol
- Apply the formula:
Mass % of H = (2.016 / 18.015) * 100 = 11.19% Mass % of O = (15.999 / 18.015) * 100 = 88.81%
- Verify the calculated value which is updated instantly in the results panel on the right.
Frequently Asked Questions
What is mass percent composition? ▼
Mass percent composition is the percentage by mass of each element present in a chemical compound.
What is the formula for element mass percent? ▼
Mass % = (Total Mass of Element in 1 mol / Molar Mass of Compound) × 100%.
Do all element mass percentages in a compound sum to 100%? ▼
Yes, the mass percentages of all individual constituent elements must total 100%.