Mole Fraction Calculator

Mole Fraction Calculator

The Mole Fraction Calculator computes the mole fraction and mole percent of a solute in a solution. Mole fraction is a unitless concentration measure that compares the moles of one component to the total moles in the mixture.

$$X_{\text{solute}} = \frac{n_{\text{solute}}}{n_{\text{solute}} + n_{\text{solvent}}}$$

When you know the total solution moles instead of solvent moles:

$$X_{\text{solute}} = \frac{n_{\text{solute}}}{n_{\text{solution}}}$$

Mole percent is simply the mole fraction multiplied by 100. The sum of all mole fractions in a solution always equals 1.

Example: A 17.5% nitric acid solution with 0.2778 mol HNO₃ and 4.5782 mol water gives $X = 0.2778 / (0.2778 + 4.5782) = 0.05721$, or 5.721 mole percent.

Related tools: Molarity Calculator, Grams to Moles Calculator, and Molecular Weight Calculator.