Question

Mole fraction of ethyl alcohol in aqueous ethyl alcohol (C2H5OH) solution is 0.25. Hence percentage of ethyl alcohol by weight is :

• A. 54%
• B. 25%
• C. 75%
• D. 46%

Answer 1

Answer: (D)

46%

Answer 2

(4)

Mole fraction of H2O = 1 – 0.25 = 0.75

$\frac{x_{CH_{2}H_{5}OH}}{X_{C_{2}H_{5}CH} + X_{H_{2}O}} = \frac{n_{C_{2}H_{5}CH}}{n_{C_{2}H_{5}OH} + n_{H_{2}O}}$

or wt. $\% = \frac{0.25 \times 46}{0.25 \times 46 + 0.75 \times 18} \times 100 = 46\%.$