Question

if any solute A dimerises in water at 1atm pressure and the boiling point of this solution is 100.52 degree C. if 2moles of A is added to 1kg of water and Kb for water is 0.52 degreeC/ molal, calculate the percentage association of A 1) 50% 2) 30% 3) 25% 4) 100%

Answer 1

it ican be proved alpha=100%

Answer 2

Answer:The correct answer is option 4.

Explanation:

The boiling point of the solution = $T_b=100.52 ^oC$

Boiling point of water at 1 atm ,T = 100 °C.

$\Delta T_b=100.52^oC-100^oC=0.52 ^oC$

$\Delta T_b=iK-b\times\frac{Moles}{\text{mass of water (kg)}}$

$0.52^oC=i0.52^oC/molal\times \frac{2}{1 kg}$

i = 0.5

                   $2A\rightleftharpoons A_2$

n =2

$i=1-\alpha +\frac{\alpha }{n}$

$\alpha =1$

The percentage of association is 100%.