# Mole Fraction

on . Posted in Fluid Dynamics

Mole fraction is the number of molecules of a given component in a mixture divided by the total number of moles in the mixture.

Source: Boundless. “Mole Fraction and Mole Percent.” Boundless Chemistry. Boundless, 21 Jul. 2015. Retrieved 10 Apr. 2016 from https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/solutions-12/concentration-units-93/mole-fraction-and-mole-percent-402-1960/

Mole fraction is the number of molecules of a given component in a mixture divided by the total number of moles in the mixture.

Source: Boundless. “Mole Fraction and Mole Percent.” Boundless Chemistry. Boundless, 21 Jul. 2015. Retrieved 10 Apr. 2016 from https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/solutions-12/concentration-units-93/mole-fraction-and-mole-percent-402-1960/

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.

### Mole Fraction formula

$$\chi_s \;=\; n_i \;/\; n_t$$     (Mole Fraction)

$$n_i \;=\; \chi_s \; n_t$$

$$n_t \;=\; n_i \;/\; \chi_s$$

Symbol English Metric
$$\chi_s$$ (Greek symbol chi) = mole fraction $$dimensionless$$
$$n_i$$ = amount of a constituent in moles $$dimensionless$$
$$n_t$$ = total amount of all constituent in a mixture of moles $$dimensionless$$

### Mole Fraction formula

$$\chi_s \;=\; n_A \;/\; n_A + n_B + n_C \ldots$$
Symbol English Metric
$$\chi_s$$ (Greek symbol chi) = mole fraction $$dimensionless$$
$$\ n_A$$ = number of moles in a solution $$dimensionless$$
$$n_A + n_B + n_C \ldots$$ = total number of moles present in the solution $$dimensionless$$