Free Mole Fraction Calculator
Use this Free Mole Fraction Calculator to work through the same calculation as the main calculator page with clear steps, examples, and result context.
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Run the calculator.
What This Free Mole Fraction Calculator Helps You Do
This page gives you the two practical ways people use mole fraction: from component moles and from ideal-gas partial pressure data.
It also returns the complementary fraction so a two-component mixture can be checked at a glance.
How to Calculate Free Mole Fraction Calculator
- Choose the method: Work from moles or from ideal-gas pressure data.
- Enter the component amount: Use either moles or pressure values.
- Divide by the total: Mole fraction is always a part-to-total ratio.
Free Mole Fraction Calculator Formula
| Variable | Meaning | Unit |
|---|---|---|
| x_i | Mole fraction of component i | dimensionless |
| n_i | Moles of component i | mol |
| P_i | Partial pressure of component i | same as total pressure |
Use the worked examples below to check how the formula behaves with real values. If the result looks unexpected, verify the unit assumptions and the meaning of each variable before interpreting the answer.
Worked Examples
- A: 2 mol
- B: 3 mol
Result: xA = 0.4 and xB = 0.6.
Each component is divided by 5 total moles.
- Partial pressure: 0.21 atm
- Total pressure: 1 atm
Result: x = 0.21.
For ideal gases, pressure ratio equals mole-fraction ratio.
How to Interpret Your Results
| Range | Meaning | Action |
|---|---|---|
| Near 0 | Minor component. | The substance contributes only a small share of the mixture. |
| Near 1 | Dominant component. | The mixture is strongly enriched in that substance. |
Frequently Asked Questions
References
Last reviewed: March 2026