Calculate the mole fraction of benzene in solution containing 30% by mass in carbon tetrachloride.

Mole fraction is equal to the moles of one component divided by the moles in the solution or mixture.

Given,

Benzene is 30% by the moles in carbon tetrachloride solution.

We get,

In 100g of solution there is 30g of benzene.

∴ Mass of carbon tetrachloride in solution is 70g

Molecular mass of benzene (C₆H₆) (6 × 12 + 6 × 1) = 78 g/mol.

Molecular mass of carbon tetrachloride (CCl₄) (1 × 12 + 4 × 35.5) = 158 g/mol.

∴ Number of moles of benzene (C₆H₆) = = 0.3846 mol

Number of moles of carbon tetrachloride (CCl₄) = = = 0.4545 mol

Thus, Mole fraction of benzene = = 0.458

∴The mole fraction of benzene = 0.458