o
o
It is denoted by the alphabet x and subscript written on the right hand side of x denotes the component of which mole fraction is being calculated .
Mathematically , Mole fraction of a component
= o
Let us consider a binary mixture of A and B . let the number of moles of A and B bee nA and nB respectively , then o
For solution where number of components = i o
In a given solution sum of the mole fractions of all the components is unity . Mathematically , x1 + x2 + x3 …. + xi = 1
Problem : Calculate the mole fraction of benzene in solution containing 30 % by mass in carbon tetrachloride .
Solution : Total mass of the solution = 100 g Mass of benzene = 30 g . ∴ Mass of carbon tetrachloride = ( 100 - 30 ) g = 70 g Molar mass of benzene ( C6H6 ) = ( 6 × 12 + 6 × 1 ) g mol – 1 = 78 g mol - 1 ∴ Number of moles of C6H6 = 30 / 78 mol = 0.3846 mol
Molar mass of carbon tetrachloride ( CCl4 ) = 1 × 12 + 4 × 355 = 154 g mol - 1