Frequently Asked Question

The mole fraction of a component in a mixture is the ratio of the number of moles of that component to the total number of moles of all components in the mixture. It is a unitless quantity and is often represented by the symbol 'X'.
Here are two examples:
Example 1: A solution of sugar in water
Suppose you have a solution containing 1 mole of sugar (C12H22O11) dissolved in 9 moles of water (H2O). The total number of moles in the solution is 1 + 9 = 10 moles.

Mole fraction of sugar (Xsugar) = (1 mole sugar) / (10 moles total) = 0.1
Mole fraction of water (Xwater) = (9 moles water) / (10 moles total) = 0.9
Example 2: A mixture of gases
Imagine a mixture of gases containing 2 moles of nitrogen (N2), 3 moles of oxygen (O2), and 1 mole of carbon dioxide (CO2). The total number of moles in the mixture is 2 + 3 + 1 = 6 moles.

Mole fraction of nitrogen (XN2) = (2 moles N2) / (6 moles total) = 0.33
Mole fraction of oxygen (XO2) = (3 moles O2) / (6 moles total) = 0.5
Mole fraction of carbon dioxide (XCO2) = (1 mole CO2) / (6 moles total) = 0.17
Key points:

The sum of the mole fractions of all components in a mixture is always equal to 1.
Mole fraction is a useful concept for expressing the concentration of a component in a mixture, especially when dealing with solutions or gas mixtures.
It is independent of the volume of the mixture and remains constant even if the volume changes.
Let me know if you have any more questions!