Mole Fraction (X)

Mole fraction may be defined as the ratio of number of moles of one component to the total number of moles of all the components (solvent and solute) present in the solution. It is denoted by the letter . It may be noted that the mole fraction is independent of the temperature. Mole fraction is dimensionless. Let us suppose that a solution contains the components and and suppose that of and of are present in it.

Number of moles of is given by, and the number of moles of is given by, where and are molecular masses of and respectively.

Total number of moles of and

Mole fraction of ,

Mole fraction of ,

The sum of mole fractions of all the components in the solution is always one.


Thus, if we know the mole fraction of one component of a binary solution, the mole fraction of the other can be calculated.

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