Question

If the molality of the dilute solution is doubled, the value of molal depression constant will be-

A. Unchanged

B. Doubled

C. Halved

D. Tripled

Answer 1

Hint: To understand better we must know what molality means, it is the freezing point depression of solutions of nonelectrolytes has been resolved to be equivalent to the molality (m) of the solute times, a proportionality constant called the molal freezing point depression constant.

Complete answer:

The molal depression constant ($K_f$) is a attributed property of the solvent. It has nothing to do with the concentration of solute. 

Molal depression constant: It is characterized as the depression in freezing point when the molality of the solution is unity, that is one mole of the solute is dissolved in 1000 grams or 1 kilogram of the solvent. 

Molality: It is characterized as the number of moles of solute present in 1 kilogram of solvent. The unit of molal depression constant is, $K kg/mole. The molal depression constant doesn't rely upon the idea of the solution. It relies upon the idea of the solvent. 

If the molality of a dilute solution is doubled, the value of the molal depression constant ($K_f$) remains unchanged. Because molal depression is constantly dependent on the nature of the solvent, not on solute.

Dilute solutions imply that the small amount of solute won't essentially change the volume of the final product or the weight of water required. In a concentrated solution, the solute will make some of the volumes, diminishing the mass of water required to make one liter.

Hence the correct option is option (A). Unchanged.

Note: $K_b$ or the proper term utilized is Molal rise constant is the boiling point elevation that happens when the solution with the molality of approximately one is spent. This sort of solution is normally known as ebullioscopy consistency. This will be created when the solute of 1 mole is dissolved in the solvent of 1kg.