§8.6 Classification of dispersion system

1. Dispersion system: One or several substances disperse in another substance serving as medium. Continuous phase: dispersion medium Domain: dispersed phase

1.2 Classification of dispersion systems According to the size of dispersed phase r / m Atom number name Phase number uniformity < 10-9 < 103 Molecular dispersion Single phase uniform 10-7~10-9 103~109 Colloidal dispersion multiphase 10-7~10-4 > 109 Coarse dispersion nonuniform Discuss the energy of highly dispersed system (of nano-scale): colloidal system !

You can find examples for all these types on our course website! 1.2 Classification of dispersion system according to state Dispersion medium Dispersed phase name Examples Gas liquid Liquid aerosol Fog, liquid sprays Solid Solid aerosol Smoke, dust foam Whipped cream Liquid Emulsion Milk solid sol paint, mud gas solid foam expanded PS gel jellies, opal Solid suspension colored glass, smoky crystal You can find examples for all these types on our course website!

You can find examples for dispersion systems on our course website!

The colloidal particles interact strongly with the dispersion medium. 1.2 Classification of colloids --- according to dispersion state Lyophilic sols: The colloidal particles interact strongly with the dispersion medium. Solution of macromolecules (not “true” solution?) Lyophobic sols: The colloidal particles and the dispersion medium has no tendency to interact. Fe(OH)3 sol

Semi-permeable membrane 1.3 What is colloids? 1862, Graham: samples Diffusion Semi-permeable membrane Crystalloids salt, sugar rapid Permeable Colloids protein, Fe(OH)3 slow Non-permeable Fundamental concepts Colloids, sol, gel, peptization, dialysis.

1908, Weimarn: Ba(CNS)2 + MgSO4: sol gel precipitation concentration diameter 1907, BanmapH 1908, Weimarn: Ba(CNS)2 + MgSO4: 10-4 ~ 10-5 mol dm-3, sol; 10-2 ~ 10-1 mol dm-3, precipitation, crystalline solid 2~3 mol dm-3, gel