Question

An aqueous solution contains $25\%$ ethanol and $50\%$ acetic acid by mass. Calculate the mole fraction of acetic acid in this solution:

• A. 0.196
• B. 0.301
• C. 0.392
• D. 0.503

Answer 1

Answer: (B)

Mole of $C_2{H}_{5}OH=\frac{25}{46}=0.54$
Mole of $C{H}_{3}COOH=\frac{50}{60}=0.83$
$\%$ of $H_{2}O=100-(50+25)=25$
$\therefore$ Mole of $H_{2}O=\frac{25}{18}=1.38$
Total number of moles $=0.54+0.83+1.39$
$=2.76$
$\therefore$ Mole fraction of acetic acid
$=\frac{0.83}{2.76}=0.301$