What is mole percent?
Warning! Long Answer. Mole percent is the percentage that the moles of a particular component are of the total moles that are in a mixture.
Let’s start with the definition of mole fraction.
The mole fraction of component a is
The more abundant component, the solvent, is usually called component 1, and the solute is called component 2.
The sum of the mole fractions for each component in a solution is equal to 1. For a solution containing two components, solute and solvent,
Mole percent is equal to the mole fraction for the component multiplied by 100 %
mole % a =
The sum of the mole percentages for each component in a solution is equal to 100 %.
For a solution containing two components, solute and solvent,
mole % solute + mole % solvent = 100 %
What are the mole fraction and mole percent of sodium chloride and the mole fraction and mole percent of water in an aqueous solution containing 25.0 g water and 5.0 g sodium chloride?
(a) Identify the components making up the solution.
(b) Calculate the moles of each component.
(c) Calculate the mole fraction of each component.
[Note: We could also have written
(d) Calculate the mole percent of each component.
Mole % 2 =
Mole % 1 =
[Note: We could also have written mole % 1 = 100 – mole % 2 = (100 – 5.8) % = 94.2 mole %]