Question

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

Answer 1

Moles of components

Molar mass of benzene $\left(C_6{H}_6\right)=(12\times 6)+(1\times 6)=78gmo{l}^{-1}$

Molar mass of $CC{l}_4=12+(35.5\times 4)=154gmo{l}^{-1}$
Therefore,
Number of moles of $C_6{H}_6=\frac{\text{Mass of benzene}}{\text{Molar mass of benzene}}=\frac{30}{78}=0.38mol$

and,
Number of moles of $CC{l}_4=\frac{\text{Mass of CCl\_4}}{\text{Molar mass of CCl\_4}}=\frac{70}{154}=0.45mol$

Mole fraction of Benzene

So, mole fraction of benzene in the given solution
$=\frac{\text{Moles of benzene}}{\text{Total moles}}=\frac{0.38}{0.38+0.45}=\frac{0.38}{0.83}=0.457$

Thus, mole fraction of benzene in the given solution $=0.457$