Mole fraction = moles of one component ÷ total moles of all components
Formula: Xᵢ = nᵢ / Σn
Find the moles of each substance
Add all moles together to get total moles
Divide the moles of the chosen substance by the total moles
The sum of all mole fractions in a mixture equals 1
Example: if a mixture has 2 mol A and 3 mol B, then X_A = 2/5 and X_B = 3/5