Question

On mixing 15.0 ml of ethyl alcohol of density 0,792g${ml}^{-1}$ with 15 ml of pure water at $4^{o}C$, the solution is found to have a density of 0.924g${ml}^{-1}$. The percentage contraction in volume is:

• A. 8%
• B. 2%
• C. 3%
• D. 4%

Answer 1

Answer: (C)

3%

Mass of alcohol $=15\times 0.792=11.88g$

Mass of water $=15\times 1=15g$

Total mass $=11.88+15=26.88g$

Volume of solution $=\frac{massofcomponents}{densityofsolution}$

$=\frac{26.88}{0.924}=29.0909mL$

Expected volume $=(15+15)=30mL$

Difference $=30–29.0909=0.909mL$

% Concentration in volume = $\frac{difference}{expectedvolume}\times 100$

$=\frac{0.909}{30}\times 100$

$=3.03$%