1. Lesson 13 Separation of Mixtures
Objectives:
The student will define a number of ways in which a mixture can be separated by physical means.

3. 1. Methods of Separating a Mixture
Mixtures can be separated by physical means.
i. Filtration: filtering out large particles from a mixture using a screen of some kind.
ii. Evaporation: allowing some atoms or molecules to go from a liquid to a gas state, leaving other atoms or molecules behind.
iii. Use of a centrifuge: spinning a mixture at high speed, causing the heavier particles to settle to the bottom, while the lighter
particles remain on the top.

4. iv. Decanting: pouring off a liquid from the top of another liquid of a solid.
v. Magnetism: using a magnet to separate one magnetic substance from another non-magnetic substance.
vi. Electrophoresis: an electric current is used to attract charged or polar particles through a gel, where heavier molecules move slower, and lighter molecules move faster.

5. Chromatography is widely used in industry.
1. Chromatography takes advantage of different substances’ affinity for paper.
2. Water or some other solvent picks up the substance and moves them.
3. The substances less attracted to the paper move faster, and more attracted move slower. This separates the substance.
4. Gas chromatography is used in the food and perfume industries.

6. viii. Distillation can be used to purify liquids mixtures.
1. Distillation takes advantage of different substances in a mixture having different boiling points.
2. By heating the substance to the boiling point of one of its components, that component can be boiled off and collected, leaving the other substances in the liquid mixture.
3. Some drinking water is made from salt water this way.
4. Oil and oil products are separated this way, in towers known as fractionating columns.

8. Distillation Apparatus

9. Questions:
1. List and define the seven methods of separation discussed in this section.
2. When 50mL of ethanol is mixed with 50 mL of water, a solution forms. The volume of the final solution is less than 100mL. Propose an explanation for this phenomenon.
3. Describe the separation technique that could be used to separate each of the following mixtures:
a. Two colorless liquids
b. A nondissolving solid mixed with a liquid
c. Red and blue marbles of the same size and mass
d. Iron and copper pellets
e. A dissolving solid mixed with a liquid (ex. salt water)