Question

x gm of water is mixed with 69 gm of ethanol. The mole fraction of ethanol in the resulting solution is 0.6. What is the value of 'x' in gm.

• A. 54
• B. 36
• C. 180
• D. 18

Answer 1

The correct option is D

18

Moles of ethanol = $\frac{69}{46}$ = 1.5
Mole fraction of ethanol is 0.6

$\therefore \frac{n_1}{n}=X_1$

$\frac{1.5}{n}=0.6$

n = $\frac{1.5}{0.6}\Rightarrow 2.5$

$n_2\left(molesof{H}_{2}O\right)=2.5-1.5=1$

$n_2=\frac{W_{H_{2}O}}{M}$

$1=\frac{W}{18}$

$W_{H_{2}O}=18gm$