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Mole Fraction Calculator

Calculate the mole fraction of each component in a mixture.

About Mole Fraction Calculator

Mole fractions always sum to one, which makes them the natural composition variable for gas mixtures and solutions. They appear directly in Raoult’s and Dalton’s laws. Mass fractions and mole fractions differ whenever components have different molar masses, and confusing them is a common source of error.

Formula

Mole Fraction

x_A = n_A ÷ n_total, and all mole fractions sum to 1

x
Mole fraction, a dimensionless ratio between 0 and 1

Worked example

With the default values below, Mole Fraction Calculator returns Mole Fraction of A of 0.400000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Moles of component Aminimum 0 mol
2 mol
Moles of component Bminimum 0 mol
3 mol
Moles of component Cminimum 0 mol
0 mol

Results

Mole Fraction of A
0.400000
Mole Fraction of B
0.600000
Mole Fraction of C
0.000000
Total Moles
5.0000 mol
Mole Percent of A
40.000%

Step by step

  1. 1Values used
  2. 2Mole Fraction
  3. 3Mole Fraction of A= 0.400000
  4. 4Mole Fraction of B= 0.600000
  5. 5Mole Fraction of C= 0.000000
  6. 6Total Moles= 5.0000 mol
  7. 7Mole Percent of A= 40.000

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 6 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Mole Fraction calculated?

x_A = n_A ÷ n_total, and all mole fractions sum to 1 Mole fractions always sum to one, which makes them the natural composition variable for gas mixtures and solutions. They appear directly in Raoult’s and Dalton’s laws.

Why does Mole Fraction matter?

Mass fractions and mole fractions differ whenever components have different molar masses, and confusing them is a common source of error.

What values do I need to enter?

This calculator takes 3 inputs: Moles of component A, Moles of component B, Moles of component C. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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