Question

An equimolar solution of non-volatile solutes A and B shows a depression in freezing point in the ratio of 2:1. If A remains in its normal state in the solution, the state of B in the solution will be ______.

पर्याय

• Normal

• Hydrolysed

• Associated

• Dissociated

Answer 1

An equimolar solution of non-volatile solutes A and B shows a depression in freezing point in the ratio of 2:1. If A remains in its normal state in the solution, the state of B in the solution will be associated.

Explanation:

The freezing point depression is given by:

ΔT_f​ = i ⋅ K_f ​⋅ m

Since K_f​ and mmm (molality) are same for both A and B, we compare the depression in freezing point using the van’t Hoff factor i:

`i_A/i_B = 2/1 => 1/i_B = 2/1 => i_B = 1/2`

• If i < 1, it means the solute associates in the solution.

• If i > 1, it indicates dissociation (like in ionic solutes).

• i = 1 implies the solute stays normal (neither associates nor dissociates).

Since i_B = 0.5 < 1, solute B is associating in the solution.