5.11 What are lyophilic and lyophobic sols? Give one example of each type. Why are hydrophobic sols easily coagulated ?
(i)Lyophilic sols- These sols are solvent loving. In these types of sols, the dispersed phase has an affinity towards the dispersion medium(liquid).example- starch, gum and protein. The affinity is due to the ability to form a hydrogen bond with the dispersion medium(water) These sols are reversible in nature.
(ii)Lyophobic sols- These are water-hating. In these types of sols, the dispersed phase has no affinity towards the dispersion medium or the solvent. example- metals, their sulphides etc. on simply mixing they do not form colloidal solution. Their colloidal sols can be prepared only by some special methods. sol particles have some positive or negative charges. Irreversible in nature.