What is mole fraction?

Mole fraction is the ratio of moles of one component to the total moles in the mixture. It ranges from 0 to 1.

Why must mole fractions sum to 1?

Because they represent proportions of the whole mixture.

How is mole fraction related to partial pressure?

By Dalton's law, partial pressure of a gas equals its mole fraction times total pressure: P_i = X_i × P_total.

Free Mole Fraction Calculator

Calculate the mole fraction of each component in a two-component mixture.

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Moles of Component A

mol

Moles of Component B

mol

Mole Fraction of A

0.4000

Mole Fraction of B0.6000

Mole Fraction of A vs Moles of Component A

View formula & how it works →

How to Calculate Mole Fraction

Formula

X_A = n_A / (n_A + n_B)

Mole fractions are dimensionless and always sum to 1.

Example Calculation

A mixture of 2 mol ethanol and 3 mol water.

01Total moles = 2 + 3 = 5
02X_A = 2 / 5 = 0.4
03X_B = 3 / 5 = 0.6

Frequently Asked Questions

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Understanding Molarity

Learn what molarity is, how to calculate it, and why it matters in chemistry. Covers moles, liters, dilution, and step-by-step examples for preparing solutions.

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