Colloids
- 1. COLLOIDS Definition and Properties of Colloids Classification of Colloids Importance of ColloidsTo Daily Life
- 2. Classify Them! brine solution ice cream soda muddy water starch solution marshmallow marbles in water butter gelatin air brass paint ruby sand and water pebbles and water soda
- 3. Solution Colloid Suspension air butter marbles in brass gelatin water brine solution ice cream soda muddy water soda marshmallow pebbles and starch solution paint water ruby sand and water
- 4. Comparison of the Properties of Solutions, Colloids, And Suspensions Property Solution Colloid Suspension Particle Size Less than 1 nm 1 to 100 nm More than 100 nm Appearance Clear Cloudy Cloudy Homogeneity Homogeneous Homogeneous or Heterogeneous Heterogeneous Transparency Transparent but Often translucent Often opaque but often colored and opaque but can be translucent can be transparent Separation Does not separate Does not separate Separates or settles Filterability Passes through Passes through Particles do not filter paper filter paper pass through filter paper
- 5. Unique Properties of Colloids Tyndall Effect A beam of light passing through a transparent pure colorless solid, liquid or gas cannot be seen except at the point where it enters and leaves the object. scattering of light
- 6. Brownian Movement If a colloid is viewed under a special microscope, the dispersed particles will be seen moving in a rapid, random, zigzag motion through the dispersion medium. This motion in a colloid is one of the reasons why particles remain suspended indefinitely.
- 7. Electric Charge A dispersed colloidal particle can adsorb electrically charged particles on its surface. opposite attracts; same repel prevents coagulation and OMG! precipitation of dispersed colloidal You’re my particles exact opposite! I think I am attracted to you!
- 8. activated carbon Adsoptive Property Adsoption is the process of collecting a thin layer of molecules or ions of a substance with which it is in contact. Surfaces of solids and liquids can adsorb molecules from fluid phases (liquids and gases) onto their surface. • Chemisorption – fairly strong, resembling chemical bonds, and difficult to break ex: activated charcoal • Physisorption – weak, involves only Van der Waals forces and the adsorbed material can usually removed again. ex: silica gel silica gel
- 9. Animation References Animation of Tyndall Effect: http://www.yteach.com/page.php/r I want to esources/view_all?id=mixture_coll see those… oid_solubility_molarity_solution_c oncentration_dilution_ion_titration _mass_percent_t_page_3&from= search Animation of Brownian Movement: www.edumedia- sciences.com/en/a247-brownian- motion
- 10. Classification of Colloids components : dispersed particles (solute) and dispersing medium (solvent) can be classified according to: Phase Affinity Between Phases Fabulous!
- 11. Types of Colloids Dispersed Dispersion Name Examples Particles Medium Gas Liquid Foam Beaten egg white, shaving cream, whipped cream, ice cream soda Gas Solid Solid foam Marshmallow, rubber foam Liquid Gas Liquid aerosols Clouds, fog, mist, hair spray, deodorant spray Liquid Liquid Emulsion Milk, mayonnaise, blood Liquid Solid Gel Cheese, butter, margarine
- 12. Dispersed Dispersion Name Examples Particles Medium Solid Gas Soild aerosol Smoke, dust in air Solid Liquid Sol Paint, starch mixture, hot chocolate, gelatin Solid Solid Solid sol Colored glass, gem glass like ruby and garnet
- 13. Classification According To Phase AEROSOLS suspension of liquid or solid particles in gas
- 14. solid foam FOAMS colloidal liquid foam dispersions of gas bubbles in liquids (liquid foams) or solid (solid foams)
- 15. EMULSIONS colloidal dispersion of liquid either a liquid or a solid. The 2 components of an emulsion are usually immiscible and require an addition of emulsifying agent or peptizing agent to form stable emulsion. If the dispersed particles in an emulsion are relatively large, they still tend to separate from the dispersion medium. This could be prevented by the a process called homogenization.
- 16. SOLS a solid dispersed in either a solid or a liquid
- 17. GELS a colloidal system in which the dispersed phase consists of fibrous, interwoven particles called fibrils which exert a marked effect on the physical properties of the dispersing medium
- 18. Classification According to Affinity Between Phases Lyophilic solvent – loving; have a strong attraction for the molecules of the dispersing medium. Lyophobic solvent –fearing; dispersed phase are actually immiscible with the solvent under normal conditions.