Question

Why is ‘raising of viscosity’ of a solution after addition of solute, not considered to be a colligative property?

(a) The resultant viscosity depends on the nature of the solute

(b) The resultant viscosity depends on the amount of solute

(c) The resultant viscosity depends on the nature of solvent

(d) The resultant viscosity depends on the amount of solvent

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This is a very interesting question from Colligative Properties and Determination of Molar Mass in division Solutions of Chemistry – Class 12

Answer 1

Right answer is (a) The resultant viscosity depends on the nature of the solute

Explanation: A colligative property is identified by the fact that it has no dependence on the nature of the particles of solute. However, in the case of viscosity it really depends on the solute that is added to the solvent. Thus, the change in viscosity after addition of a non-volatile solute cannot be considered to be a colligative property.