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.