Question

Which of the following statements is correct?

(a) Solutes that dissociate in water have molar mass higher than the molar mass of the solute calculated theoretically

(b) Solutes that associate in water have molar mass higher than the molar mass of the solute calculated theoretically

(c) Solutes that dissociate in water experience a decrease in colligative properties

(d) Colligative properties are independent of the number of particles of the solute in the solution

I had been asked this question during an online interview.

I need to ask this question from Abnormal Molar Masses topic in section Solutions of Chemistry – Class 12

Answer 1

Right choice is (b) Solutes that associate in water have molar mass higher than the molar mass of the solute calculated theoretically

For explanation: On association of solute molecules, the number of particles in a solution is reduced. Since, colligative properties are directly proportional to the number of particles in a solution, the colligative properties reduce. The molecular mass of the solute is inversely proportional to its colligative properties. Therefore, solutes that associate in water have a higher molar mass than its value calculated theoretically.