Mole Fraction Calculator

Mole fraction describes the composition of a mixture by comparing the amount of one component with the total amount of all components. For component i, its mole fraction equals its moles divided by total moles. The result has no unit and normally lies from zero to one. All component mole fractions in a complete mixture add to one, making the measure especially convenient for gases, liquid solutions, phase-equilibrium work, and thermodynamic equations. This calculator accepts three mole amounts, adds them to find the mixture total, and divides each amount by that total. It also multiplies each fraction by 100 to report mole percent. For example, a mixture containing two moles of one substance and three moles of another contains five moles overall. Their mole fractions are 0.4 and 0.6, or 40 and 60 mole percent. A third component can be represented by zero when only a binary mixture is needed. Unlike mass fraction, mole fraction counts chemical entities rather than their mass contribution. Equal masses of two compounds generally do not produce equal mole fractions because their molar masses differ. If your measurements are in grams, first divide each component mass by its molar mass. Then enter those converted mole amounts here. This distinction matters when calculating vapor pressure with Raoult's law, partial pressure with Dalton's law, chemical potential, or a reaction mixture's composition. Mole fraction remains unchanged if every component amount is scaled by the same factor. A ratio of 1:2:3 produces the same fractions as 10:20:30 because only relative amounts matter. Values must be nonnegative, and the total must exceed zero. Keep every amount in the same unit; mol, mmol, or kmol all work when used consistently because the common unit cancels during division. The displayed decimal precision is suitable for most educational and laboratory planning tasks. Retain extra digits through intermediate work, then round the final composition to match the precision of the measured amounts. The sum of rounded percentages may occasionally appear slightly above or below 100 percent, which is a display-rounding effect rather than a calculation error. For mixtures with more than three substances, combine trace components when scientifically appropriate or repeat the calculation externally with the same amount-over-total formula.