What is mole percent? Give an example

Mole percent is the number of moles of a component divided by the total number of moles of all components, multiplied by 100. 

In chemistry, when a solution contains more than one substance, we often measure how much of each substance is present using moles. The mole percent (also called molar percent) tells us the percentage of a particular substance out of the total number of moles present in the mixture.

The formula is:

Mole percent = (moles of a component / total moles of all components) × 100

Example: Suppose we have a solution containing 2 moles of salt (NaCl) and 8 moles of water (H₂O).

Total moles = 2 (NaCl) + 8 (H₂O) = 10 moles

Mole percent of salt = (2 / 10) × 100 = 20%

Mole percent of water = (8 / 10) × 100 = 80%

Mole percent is useful in understanding how much of a chemical is present in a reaction mixture, solutions, or alloys. It is especially important in chemical engineering and solution chemistry.