Mixtures

Mixtures are 2 or more substances (elements or compounds or both) that do not combine chemically during the mixing.  The parts are not chemically combined.  There is a variable proportion of components and the properties of these components remains the same as before the mixing.  The parts can be separated by physical means.   Examples:  ice tea, concrete, granite
 
Types:

1. heterogeneous -> can divide this type mixture in half and not get 2 identical halves (can see at least 2 parts)  examples: concrete, ice tea, wood

2. homogeneous -> 2 or more components so evenly distributed that if its divided in half you can't tell the difference between them   examples: quartz, glass

3. emulsion -> a mixture of of 2 immiscible liquids (liquids that do not mix), may separate back out in time and emulsifiers may be used to keep droplets small  example: oil & vinegar, paint, hand creme

4. alloy  -> a mixture of 2 or more metals melted together having new and different properties from the individual metals   example: brass, bronze, pewter

5. amalgam  -> alloy that contains mercury    example: dental filings

6. solutions  -> typically a liquid homogeneous mixture containing a dissolved substance
   solvent -> component in largest concentration
   solute  -> component in smallest concentration
   aqueous  -> solvent is water    (example: Kool-Aid)
   tincture  -> solvent is alcohol

7. colloids - click to see page of information

Methods to separate mixtures:

1. filtration

2. distillation  -> must know boiling points of two liquids

3. recrystallization  -> must know melting points and crystal structures  (example: ice berg)

4. use of centrifuge  -> differences in densities

5. solubility  -> know nature of substances (example:  polar molecules and ionic compounds dissolve in polar solvents)

6. size

7. magnetic attraction

8. electrical attraction

9. chromatography -> separate due to differences in affinity to surface versus their affinity to solvent

Definitions:

1. dilute solution:  small amount of solute compared to amount of solvent

2. concentrated solution:  contains more solute than a dilute solution

3. saturated solution:  when solvent cannot hold any more solute at that temperature

4. solubility:  maximum amount of solute that can be dissolved in a given amount of solvent at a specified temperature

5. suspension:  heterogeneous mixture in which one of the parts is a liquid (visible particles will settle out of any suspension - example = oil and vinegar)

6. colloids:  particles small enough that they do not settle out (particles do not sink to bottom of containers and usually are too small to be visible (example = gelatin, cold cream, lipstick, shaving cream)

7. gels:  colloid in which liquid particles are spread out in a solid (example: gelatin, jelly, stick deodorant)

8. emulsion:  colloid of 2 liquids (example: mayonnaise, hand cream, milk, salad dressing)

9. aerosol:  colloid in which either solid or liquid particles are suspended in a gas (example = fog or smoke)

Page Last Updated: Friday March 02, 2007           Webmaster: Larry Jones                 Pickens County School District