Disperse Systems - ALL NOTES Flashcards
What are the features of a solution?
-Mono-phase system
-Molecular dispersion
-Cannot be filtered
-Do not scatter light
What is disperse system?
-One phase distributed in a disperse phase
-Two immiscible phases in contact
What is a colloid?
-A two phase mixture of matter intermediate between homogenous and heterogenous mixture
-Small droplets of one substance dispersed in another
What is the Tyndall effect?
-The scattering of light by colloidal particles
What are the properties of colloids?
-Tyndall effect
-brownian motion
-adsorption
-electrophoresis
What is Brownian motion?
-The bombardment of smaller molecules on larger molecules which keep them in suspension in the liquid
What is adsorption?
-The process in which material travels from a liquid or gas phase and forms a superficial monomolecular layer on the solid phase
What is dialysis?
-Separation of suspended colloidal particles from dissolved ions or molecules of small dimensions through pores of semi-permeable membranes
What is electrophoresis?
-The migration of charged particles under the influence of an electric field
What is thixotropy?
-Viscous fluids will become flexible and flow when agitated and return to more gelatinous state after static period
What are the types of colloids?
-Lyophobic nd lyophilic
What is lyophilic ?
-Solvent loving
What is lyophobic?
-Solvent hating
What is the difference between a solution and colloidal dispersion?
-A solution is always a liquid whereas a colloidal dispersion can exist in different phases
what is a sol?
-A colloidal dispersion of a solid dispersed in a liquid
What is a gel?
-A colloidal system in which the liquid medium has become viscous enough to behave like a solid
What is a foam?
-A gas dispersed in liquid
How do defamers work?
-Foam breakers that displace surfactants at the air-water interface
What is surface tension?
-A measure of how difficult it is to stretch or break the surface of a liquid
What is a surfactant?
-A substance that reduces surface tension that consists of hydrophobic and hydrophilic regions
What is a cationic surfactant ?
-Positively charged surfactant, negative counter ion
What is a non-ionic surfactant?
-Uncharged surfactant
What is a zwitterion?
-A zwitterion is a species with both a positive and a negative charge but an overall neutral charge
Why is a co-surfactant sometimes added?
-To achieve very low surface tension
What is a micelle?
-Colloidal spherical nanoparticles that constantly breaking down and reforming
