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The colligative properties are properties of solutions which depend only upon the number of solute…
The colligative properties are properties of solutions which depend only upon the number of solute particles irrespective of their nature. These properties help to calculate the molecular weight of non-volatile, non-dissociating and non-associating solutes. If the solute dissociates or associates, we get abnormal molecular weights. To account for abnormal molecular weights of such solutes, van’t Hoff factor ($i$) was introduced.
(i)[2.0]
When $1\cdot90\text{ g}$ of benzoic acid is dissolved in $26\text{ g}$ of benzene, it causes a depression in freezing point by $1\cdot60\text{ K}$. The molal depression constant for benzene is $4\cdot8\text{ K kg mol}^{-1}$ and the molecular mass of benzoic acid is $122\text{ g mol}^{-1}$. Calculate the degree of association of benzoic acid if it forms dimer in solution.
(ii)[1.0]
Arrange the aqueous solution of the following compounds in the increasing order of value of van’t Hoff factor:
Benzoic acid, Barium chloride, Urea
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From ISC 2025 Improvement Chemistry Paper 1, question 13.