Question

To which of the following variables is change in boiling point directly proportional?

A. molarity of solution
B. molality of solution
C. percent by volume of solution
D. percent (mass/volume) of solution

Answer 1

Answer : The correct option is, (B) molality of solution

Explanation :

Elevation in boiling point : It is a colligative property in which the magnitude of the boiling point elevation is directly proportional to the molality of the solution.

Formula used for Elevation in boiling point :

`\Delta T_b=k_b* m`

or,

`T_(solvent)-T_(solution)=k_b* \frac{\text{ Moles of solute}* 1000}{\text{ Mass of solvent in Kg}}`

where,

`\Delta T_b` = change in boiling point

`k_b` = boiling point constant

m = molality

Hence, the correct option is, (B) molality of solution

Answer 2

I believe the correct answer is B. It is the molality of the solution that is directly proportional to the boiling of the solution. This phenomenon is called the boiling point elevation. It is one of the colligative properties of solutions together with the freezing point depression, vapor pressure lowering and osmotic pressure.