Which one of the following statements is FALSE for hydrophilic sols?
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Contrast the properties of hydrophilic vs. hydrophobic (lyophilic vs. lyophobic) sols. Hydrophilic: reversible, highly stable, high viscosity, hard to coagulate. Hydrophobic: irreversible, less stable (needs charge), low viscosity, easy to coagulate with small amounts of electrolyte.
Their viscosity is of the order of that of H$_2$O.
The sols cannot be easily coagulated.
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The Correct Option isC
Solution and Explanation
Let's analyze the properties of hydrophilic (lyophilic) sols. These are colloids where the dispersed phase has a strong affinity for the dispersion medium (e.g., starch in water).
(A) They do not require electrolytes for stability: This is TRUE. Hydrophilic sols are stabilized primarily by the solvation (hydration) layer around the colloidal particles, which prevents them from aggregating.
(B) These sols are reversible in nature: This is TRUE. If the dispersion medium is evaporated, the sol can be reconstituted by simply adding the medium back and shaking.
(C) Their viscosity is of the order of that of H$_2$O: This is FALSE. Due to the strong interaction and extensive solvation between the dispersed particles and the medium, hydrophilic sols are much more viscous than the dispersion medium itself. In contrast, lyophobic sols have a viscosity that is nearly the same as the medium.
(D) The sols cannot be easily coagulated: This is TRUE. Because of their high stability from solvation, they require a large amount of electrolyte to cause coagulation (salting out).
The false statement is (C).
