Question

Van’t Hoff factor for a dilute solution a dilute solution of glucose is:
A.0
B.1
C.$1.5$
D.2

Answer 1

Hint: The Van’t Hoff factor is a ratio of the actual concentration of the solute in the solution to the theoretical concentration and is a measure of the effect of the solute on the colligative properties of solution.
Formula Used:
Van’t Hoff factor = $\dfrac{{{\text{Actual number}}}}{{{\text{theoretical number}}}}$

Complete step by step answer:
As per the formula of the Van’t Hoff factor, it is ratio of the actual number of solute particles in the solution to the theoretical number and this is applicable to those solute particles that either associate with each other in the solution, (such as the acetic acid dimer due to hydrogen bonding) or dissociate in the solution due to their ionic nature (for example ${\text{ NaCl, KCl, NaOH }}$ etc. ).
In case of glucose, there is no such association or dissociation, because it is a covalent molecule and hence a non-electrolyte.
Hence, the number of solute particles stays the same and the Van’t Hoff factor is 1.

Hence option B is correct.

Note:
For solutes that dissociate in the solution, the Van’t Hoff factor is always greater than 1 because the degree of dissociation of the molecules is greater than 1. This is because ions forming from the parent molecule are always greater in number.
For solutes that associate in the solution, the Van’t Hoff factor is less than 1 because the molecules associate together contributing as a single species. The formation of dimers and trimers is a classic example of this association.