Question

138 g of ethyl alcohol is mixed with 72 g of water. The ratio of mole fraction of alcohol to water is:

• A. $3:4$
• B. $1:2$
• C. $1:4$
• D. $1:1$

Answer 1

The correct option is A $3:4$

Mole fraction of ethyl alcohol $=\frac{n_{alcohol}}{n_{alcohol}+n_{water}}$

Mole fraction of water $=\frac{n_{water}}{n_{alcohol}+n_{water}}$

The ratio of mole fraction of ethyl alcohol to water $=\frac{n_{alcohol}}{n_{water}}$ $=\frac{\frac{138}{46}}{\frac{72}{18}}$ $=\frac{3}{4}$

Hence, the ratio is $3:4$.