2 1. Dispersion system: One or several substances disperse in another substance serving as medium. Domain: dispersed phase Continuous phase: dispersion medium
3 According to the size of dispersed phase r / mAtom number namePhase numberuniformity < 10 -9 < 10 3 Molecular dispersion Single phaseuniform 10 -7 ~10 -9 10 3 ~10 9 Colloidal dispersion multiphaseuniform 10 -7 ~10 -4 >10 9 Coarse dispersion multiphasenonuniform 1.2 Classification of dispersion systems
4 Dispersion medium Dispersed phase nameExamples GasliquidLiquid aerosolFog, liquid sprays SolidSolid aerosolSmoke, dust liquid GasfoamWhipped cream LiquidEmulsionMilk solidsolpaint, mud solid gassolid foamexpanded PS liquidgeljellies, opal solid Solid suspensioncolored glass smoky crystal 1.2 Classification of dispersion system according to state
5 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 1.2 Classification of colloids --- according to dispersion state
6 1862, Graham: samplesDiffusionSemi-permeable membrane CrystalloidsSalt, sugarRapidPermeable ColloidsProtein, Fe(OH) 3 slowNon-permeable Colloids, sol, gel, peptization, dialysis. 1.3 What is colloids? Fundamental concepts
7 10 -4 ~ 10 -5 mol dm -3, sol; 10 -2 ~ 10 -1 mol dm -3, precipitation, crystal, 2~3 mol dm -3, gel 1908, Weimarn: Ba(CNS) 2 + MgSO 4 : 1907, BanmapH sol gel precipitation concentration diameter