Question

Molal elevation constant is also known as:

• A. Ebullioscopic constant
• B. Gas constant
• C. Henry’s constant
• D. Cryoscopic constant

Answer 1

The Correct Option is A

In the study of solutions, particularly in Chemistry, the molal elevation constant is a term used when discussing the colligative properties of solutions. The colligative properties depend on the amount of solute particles in a solution, rather than the identity of the solute itself. One such property is the elevation of the boiling point, commonly observed when a solute is dissolved in a solvent.

When a non-volatile solute is added to a solvent, the boiling point of the solution is higher than that of the pure solvent. This phenomenon is due to the decrease in the solvent's vapor pressure, requiring a higher temperature to reach boiling. The change in boiling point, ΔT_b, can be described using the equation:

ΔT_b = K_b × m

Where:

• ΔT_b is the boiling point elevation.
• K_b is the molal elevation constant, also known as the ebullioscopic constant.
• m is the molality of the solution, defined as moles of solute per kilogram of solvent.

The term "ebullioscopic constant" originates from the Latin word "ebullire" meaning to boil, and it quantifies how much the boiling point increases per molal concentration of the solute.

Based on the given options, the correct answer is: Ebullioscopic constant

Answer 2

The molal elevation constant is known as the ebullioscopic constant. This constant is used to determine the elevation in boiling point of a solvent when a solute is dissolved in it, based on the colligative properties. It is specific to each solvent and expressed in units of K.kg/mol. The ebullioscopic constant (K_b) can be used in the formula: 

ΔT_b = K_b × m

Where, ΔT_b is the change in boiling point, and m is the molality of the solution. Molal elevation constant emphasizes the relationship between a solute's effect on the boiling point and its molal concentration in the solvent, hence the term "ebullioscopic" from "ebullition," meaning boiling.

Constant	Description
Ebullioscopic constant	Determines boiling point elevation of solvents.