1. Section 2.3 Classifying Matter
Objectives/Goals:
1. To learn to distinguish between mixtures and pure substances
2. To learn methods of separation

2. A. Mixtures & Pure Substances
Mixtures: something that has variable composition
Ex: wood, soda, coffee, water, air
Air:
Neon, Helium, Nitrogen, Oxygen, Water vapor, Argon, Carbon dioxide

3. Alloys: mixtures of metals

4. Compound vs. Mixture
A compound contains only particles of identical atomic composition; always has same composition.
ex: Water (H2O)
A mixture is a collection of compounds and/or elements that are present in various amounts.
Has VARIABLE composition (depends what its made out of and how much)

5. Pure Substances-
Always has same composition. (Either a pure element or a compound)
Mixtures
2 or more pure substances
Air
Oxygen
Nitrogen Water
Argon Carbon Dioxide

6. Homogeneous & Heterogeneous Mixtures
Homogeneous mixture: A mixture that is the same throughout (salt water, air, Kool-Aid)
Solution: A homogeneous mixture
Heterogeneous Mixture: A mixture containing regions with differing properties (oil & water, sand & water, chilli)
*NOT UNIFORM THROUGHOUT

7. Mixtures & Pure Substances
Pure Substance, homogeneous mixture, or heterogeneous mixture?????
a. Gasoline
b. A stream with rocks on the bottom
c. Air
d. Copper metal
e. Maple syrup
f. Oil and vinegar salad dressing
g. Salt

8. B. Separation of Mixtures
Distillation: A separation process that depends on the different boiling points of the substances
Precipitate forms
No chemical change occurs!

9. Filtration: Separation of a solid from a liquid by using filter paper
Liquid passes through the filter paper, but the solid stays behind
Physical change