1. HETEROGENEOUS AQUEOUS SYSTEMS Chapter 15.3

2. OBJECTIVE I will be able to distinguish between suspensions, solutions, and colloids

3. SUSPENSIONS Definition: A heterogenepous mixture from which particles settle out upon standing –Particles are larger (greater than 1000nm) –Particles don’t stay suspended forever

4. COLLOIDS Definition: A heterogeneous mixture containing particles that range in size from 1nm to 1000 nm –Particles spread throughout the dispersion medium (solid/liquid/gas) –Examples: glue, paint, gelatin aerosol sprays, milk, smoke

5. Biggest difference between all three is size of particles –Solutions and colloids both appear to be uniform throughout, however particle size is different –Suspensions and colloids can both be cloudy/milky in appearance, however particle size is different COLLOIDS

6. Distinguishing Colloids 1. 2. 3. 4. COLLOIDS

7. ________________ –The scattering of visible light by colloidal particles COLLOIDS

8. ________________ –Chaotic movement of colloidal particles Under the microscope, flashes of light (scintillations) are seen due to the reflecting and scattering of the light by particle movement –Colloid particles collide with molecules which keeps particles from settling out COLLOIDS

9. ________________ –Destroying a colloidal system by adding ions with opposite charges of the colloidal particles Colloidal particles can adsorb (hold on its surface) ions and take their charge This keeps colloidal particles suspended because like charges repel COLLOIDS

10. ________________ –Colloidal dispersion of a liquid in a liquid Examples: –Soap and detergent –Butter/margarine –Mayonnaise COLLOIDS