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


Best Answer

Lyophilic sols Colloidal sols directly formed by mixing substances in a suitable dispersion medium are called lyophilic sols. These are quite stable. These are also known as reversible sols because the dispersion medium can be separated from the colloid by means of physical methods like evaporation. e.g., gum, gelatin, starch, rubber, etc.

            Lyophobic sols (Liquid hating) Such sols are not formed by simply mixing the substances with the dispersion medium. These are not stable, i.e., these sols are coagulated easily when a small amount of electrolyte is added to them or they are heated or shaked. These sols need stabilising agents for their preservation, e.g., gold sol, AS2O3, Fe(OH)3, etc.

            Reason for cogulation of hydrophobic sols These sols  are precipitated due to the removal or neutralization of charge on their particles, i. e., they come nearer, form aggregate and settle down, (in other Words, coagulation ,or precipitation occurs.) This is done by addition of a small amount of electrolyte.

 

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