Question

A mixture of ethanol and $CC{l}_4$ has $30\%$ $CC{l}_4$ by weight, what is mole fraction of $CC{l}_4$ in the mixture?

• A. $0.11$
• B. $0.89$
• C. $0.25$
• D. $0.67$

Answer 1

The correct option is A $0.11$

$30\%$ $CC{l}_4$ by weight contains $30g$ $CC{l}_4$ in $100g$ mixture.

$\therefore$ Mass of ethanol $=100-30=70g$

Moles of $CC{l}_4=\frac{30}{154}=0.195$

Moles of ethanol $=\frac{70}{46}=1.521$

$\therefore$ Mole fraction of $CC{l}_4=\frac{0.195}{0.195+1.521}=0.11$