Question

What are lyophilic and lyophobic sols? Give one example of each type. Why are hydrophobic sols easily coagulated?

Answer 1

In lyophilic sols, the dispersed phase particles have great affinity (or love) for the dispersion medium. These sols are reversible. Examples include gum, gelatin, starch, proteins and rubber etc.
In lyophobic sols, the dispersed phase particles have no affinity (or love) for the dispersion medium. These sols are irreversible. Examples include solutions of metals such as gold and silver, metal hydroxides and metal sulphides.
The hydrophobic sols are less stable and easily coagulated than hydrophilic sols because, the stability of hydrophobic sols is due to charge only and the stability of hydrophilic sols is due to charge and solvation/ hydration.