Question

What are lyophilic and lyophobic sols? Which of these sols can be easily coagulated with the addition of small amounts of electrolytes?

Answer 1

Lyophilic sols

• The term 'lyophilic' refers to liquid loving.
• ''Colloidal sols directly formed by mixing substances like rubber, gum, gelatine, starch, etc., with a suitable liquid (the dispersion medium) are called lyophilic sols.''
• These sols are also called reversible sols.

Lyophobic sols

• The term 'lyophobic' refers to liquid hating.
• “Substances like metals, their sulfides, etc., when simply mixed with the dispersion medium do not form the colloidal sol. Such sols are called lyophobic sols”.
• These sols are also called irreversible sols.

Effect of addition of small electrolyte on sols

• Lyophilic sols are very stable and do not coagulate easily.
• Lyophobic sols rapidly precipitate (or coagulate) when small amounts of electrolytes are added, by shaking or heating, and so are not stable.