Question

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

Answer 1

Let us consider that the mass of the solution is 100 grams

In the case of Benzene:

Mass of benzene = 30 grams

molar mass of benzene = 78

$Numberofmoles=\frac{Weightingrams}{Molecularweight}$

Number of moles of benzene = $\frac{30}{78}=0.38$

In the case of Carbon tetrachloride:

mass of carbon tetrachloride = 70

molar mass of carbon tetrachloride = 154

$Numberofmolesofcarbontetrachloride=\frac{Givenmassofcarbontetrachloride}{Molecularmassofcarbontetrachloride}$

Number of moles of carbon tetrachloride = $\frac{70}{154}=0.45$

Therefore, the total number of moles = 0.38+0.45 = 0.83

Now,

$Molefractionofbenzene=\frac{Numberofmolesofbenzene}{Numberofmolesofbenzene+Numberofmolesofcarbontetrachloride}$

$Molefractionofbenzene=\frac{0.38}{0.38+0.45}=0.461$

Conclusion: Thus, the mole fraction of benzene is 0.461