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

Explanation

Let the mass of solution = 100 g
Then, mass of benzene in the solution = 30 g
` therefore ` Mass of carbon tetrachloride = 100 - 30 = 70 g
Molar mass of benzene `(C_6H_6) = (6 xx 12) + (6 xx 1) = 78 g "mol"^(-1)`
Molar mass of `"CCl"_4 = 12 + 4 xx 35.5 = 154 g "mol"^(-1)`
Number of moles of benzene = `(30g)/(78 g"mol"^(-1) ) = 0.385 `mol
Number of moles of `"CCl"_4 = (70g)/(154 g "mol"^(-1) ) = 0.455 ` mol
Mole fraction of benzene = `(0.385)/(0.385 + 0.455) = (0.385)/(0.84) = 0.458 `
Mole fraction of `"CCl"_4 = 1 - 0.458 = 0.542` .