Question

Molal elevation constant is a characteristic constant for a given solvent. Is the given statement true or false?

Answer 1

Hint: As we know that molal elevation constant is basically the elevation in boiling point of a substance which is produced when one mole of the solute is dissolved in per kilogram of a solvent. The other name for the Molal elevation constant is Ebullioscopic constant.

Complete step by step answer:
As we know that the temperature at which vapour pressure of the liquid becomes equal to the atmospheric pressure is called its boiling point. And property of increases in this boiling point is called elevation in boiling point which is given as:

\[\Delta {T_b} = {K_b} \times m\]

${K_b}$ is called the Molal elevation constant and is commonly called the boiling point elevation constant of solutions. And it is defined as the elevation or increase in the boiling point of a solute produced when one mole of when one mole of the solute is dissolved in one kilogram of a solvent or in other words we can say that it is an increase in boiling point when the molality of the solution is unity.
-Therefore we can say that it is dependent on the nature of the solvent and independent of the nature of solute.
-Hence the given statement that is ‘Molal elevation constant is a characteristic constant for a given solvent’ is true.

Note: Just like the elevation in boiling point, we can calculate the depression in freezing point which is defined as the property of decrease in the freezing point when some non-volatile solute is dissolved and is given as: \[\Delta {T_f} = {K_f} \times m\] where ${K_f}$ is the Molal depression constant also known as cryoscopic constant.
Both the elevation in boiling point and depression in freezing point are the colligative properties.