1. 12.7 – NOTES Heterogeneous Mixtures

2. IV. Heterogeneous Mixtures
Suspensions - mixtures do NOT undergo a chemical change; mixture in which large particles will eventually settle out
Cornstarch and water, OJ with pulp, Italian salad dressing; can separate using a filter
thixotropic – suspension when stirred will flow, but quickly thickens to solidlike state; house paint; corn starch and water

4. Emulsion – special suspension occurs b/t two liquids
Miscible: when two liquids are soluble in each other; alcohol and water;
Immiscible: when two liquids are not soluble in each other; oil and water;
Emulsifying agent: chemical substance that coats the surface of droplets of one liquid so that they can remain dispersed throughout a second liquid (eg margarine or ice cream) forming a stable emulsion.

6. B. Colloids particles larger than solvated particles, but smaller than suspended particles; remain permanently suspended; cannot be separated by filtration or settling;

7. Brownian motion - erratic movement of colloidal particles
- results from collisions of particles of the dispersion medium with the dispersed particles
- prevents the colloid from settling
- dispersed particles do not settle out b/c charged groups on the surface are attracted to the charged groups of the medium
- creates electrostatic layers that repel each other forcing the particles to remain suspended
- heat can disrupt the colloid;

8. Tyndall effect dilute colloids appear to be homogenous, but particles will scatter light; positive Tyndall effect – presence of colloidal particles, light is scattered