Name any four examples of preparation of colloids by chemical methods with necessary chemical equations.

Explanation

Chemical methods : Colloidal solutions are prepared by chemical reactions leading to the formation of species by double decompositon , oxidation , reduction or hydrolysis . These species then aggregate leading to the formation of sols.
`As_(2)O_(3) +3H_(2)S overset("Double decomposition") to As_(2)S_(3) ("sol") + 3H_(2)O`
`SO_(2) + 2H_(2)S overset("Oxidation")to 3S("sol)+ 2H_(2)O`
`2AuCl_(3) + 3HCHO + 3H_(2)O overset("Hydrolysis ")to Fe(OH)_(3) ("sol") + 3HCl`