Question

On mixing 15.0 ml of ethyl alcohol of density 0.792 g ml-1 with 15 ml of pure water at 4°C, the resulting solution
is found to have a density of 0.924 g ml-1. The percentage contraction in volume is :
(1) 8%
(2) 2%
(3) 3%
(4) 4%
​

Answer 1

Answer:

mass of ethyl alcohol = 15×7.92 =11.88 gm.

Mass of water = 15× 1=15 gm

Total mass of solution =15+11.88

= 26.88 gm

$density = \frac{mass \: of \: solution}{volume}$

$0.924 = \: \frac{26.88}{v}$

v = 29.09 ml

concentration = 30 - 29.09 = 0.909 ml

$\% \: of \: conc.= \frac{0.909}{30} \times 100$

= 3.03%

Hence, according to Ur option (3) 3% is the correct answer.

Answer 2

Answer: 2%

Using percentage contraction formula,

Option (2)