Mole Fraction

Mole fraction, abbreviated as \(\chi_A \) (Greek symbol chi), a dimensionless number, is the number of molecules (moles) of a solution in a mixture divided by the total number of moles present in the solution.  Mole fraction is a number between 0 and 1.000 and expressed as a percentage.

Mole fraction is commonly used in various fields of science and engineering, such as chemistry, physics, and thermodynamics.  It's a useful way to express the composition of mixtures, especially in situations where the quantities of different components might vary widely or where precise control over composition is important.  For example, in gas mixtures, the mole fraction of a gas component $i$ is the ratio of the number of moles of that gas to the total number of moles of all gases in the mixture.  Similarly, in solutions, the mole fraction of a solute in a solvent indicates the proportion of solute molecules to total moles of solute and solvent combined.

Mole fractions are often used in various calculations, including determining partial pressures of gases in a mixture, calculating vapor pressure over solutions, and understanding phase equilibria in multicomponent systems.