Mole Fraction

Mole Fraction tutorial

In addition to molarity, another way to describe the composition of a solution is the mole fraction. Mole fraction is the ratio of the number of moles of a given component in a mixture to the total number of moles in the mixture.

For example: If 38.0 grams of sodium chloride is dissolved in 880. grams of water, what is the mole fraction of sodium chloride in water?

You must first convert grams to moles by dividing the compound's molar mass.
(38.0 grams sodium chloride) / (58.5 grams/mole) = 0.650 moles sodium chloride
(880. grams water) / (18.0 grams/mole) = 48.9 moles water

Now, plug it in the formula and solve.
Mole fraction of sodium chloride = 0.650 moles / (0.650 moles + 48.9 moles) = 0.0131

There is no unit used for mole fraction solutions.