Question

The elevation in boiling point for one molal solution of a solute in a solvent is called
(A) Boiling point constant
(B) Molal elevation constant
(C) Cryoscopic constant
(D) None of these

Answer 1

Hint: Colligative properties are those that depend on the concentration of the solute and do not depend upon the nature of the solute. This means two solutes of different kinds have the same colligative properties if the two solutes have the same concentration. One such type of colligative property is elevation in boiling point. Elevation means an increase.

Complete Step by Step Solution:
Elevation in boiling point refers to the increase in boiling point of the solvent when non-volatile solute is added to it. It is given by \[\Delta {T_b} = i{K_b}m\].where \[{K_b}\]is known as molal elevation constant. And \[\Delta {T_b}\] is known as the elevation in boiling point or the increase in boiling point. M is the molality of the solute and I is the van’t hoff factor.

If \[i = 1\]and it is given that the concentration of a solute is one molal. Thus, \[\Delta {T_b} = {K_b}\]. Thus, the molal elevation constant is defined as the elevation in boiling point for one molal solution of a solute having van’t hoff factor unity.
Thus. The correct option is B.

Note: Molal elevation constant is also known as ebullioscopic constant. It is a property of a solvent and hence depends on the type of the solvent. It's S.I. unit is \[Kkgmo{l^{ - 1}}\]. The empirical formula, which is defined as the ratio of subscripts of the least whole number of the elements present in the formula, is the simplest formula for a compound. The simplest formula is another name for it. The formula of a material expressed with the smallest integer subscript is referred to as an empirical formula for a compound. The empirical formula provides details regarding the ratio of atom counts in the molecule. A compound's empirical formula is directly related to its % content.