1. Solutions and mixtures

3. Quick Review An element is a substance made up of atoms of one kind.
A molecule is formed when atoms of the same elements combine.
Two atoms of oxygen combine to form a molecule of oxygen [O2]
A compound is formed when atoms or molecules of different elements combine chemically.
Hydrogen and oxygen are combined in a fixed proportion of 2:1 to form the compound water [H2O].
Mixtures are two or more substances that are mixed together but not chemically joined.

4. Pure vs. Mix A pure substance:
cannot be separated into 2 or more substances by physical means
has uniform composition throughout the whole sample
A mixture:
can be separated into 2 or more substances by physical or mechanical means
displays the properties of the pure substances making it up
its composition can be varied by changing the proportion of pure substances making it up
heterogeneous substances, ones with non-uniform composition throughout the sample, are always mixtures

5. Mixtures
When a mixture’s components are easily recognizable, such as pizza, it is called a heterogeneous mixture.
In a homogeneous mixture such as chocolate milk, the component particles cannot be distinguished, even though they still retain their original properties.

6. More on mixtures
Homogeneous – particles distributed evenly; the same throughout
Heterogeneous – PARTICLES not evenly distributed; NOT THE SAME throughout

7. Type of Mixture
Example
gas in gas
The atmosphere is a mixture of gases, mostly nitrogen and oxygen.
liquid in liquid
Wine is a mixture of mostly ethanol and water.
solid in solid
Alloys, such as brass, are made up of a mixture of metals.
gas in liquid
Soft drinks, such as cola, are mixtures of mainly carbon dioxide gas and water.
solid in liquid
Sea Water is a mixture of salts dissolved in water.
solid in gas
Smoke is mixture of tiny solid particles in atmospheric gases.

8. Solution aka Homogenous Mixture
Solutions are composed of one or many solute(s) and only 1 solvent
Solute: substance that dissolves into the solvent
Solvent: substance that dissolves the solute(s)

9. A solution can exist in any of the 3 states of matter: (solid, liquid or gas) Solid Solutions ex: brass = copper + zinc This is called an alloy. (solvent) (solute) Gas Solutions ex: air = nitrogen + oxygen + argon + carbon dioxide (solvent) (solutes) Liquid Solutions ex: vinegar = acetic acid + water (solvent) (solute)

10. Compounds vs Mixtures Mixtures Compounds
Combine chemically forming molecules
Not chemically combined
Combine in set proportions
Can combine in any proportion
Separated chemically
Separated physically