Definitions for "Mole fraction"
The amount of a substance expressed as a fraction of the total number of molecules that are present. It ranges between 0 (none of the substance is present) to 1 (pure substance).
the moles of a component substance divided by the total moles of solution
the fraction of moles (or molecules) of one substance in the total moles (or molecules) of all substances in the mixture. If the mole fraction of substance A is 0.1, one-tenth of all the molecules in a mixture are A molecules.