1. Chapter 17: Classification of Matter Section 2: Properties of Matter
If you imagine a 19th century gold miner, you may think of someone standing in a river swirling a pan. Panning was a common technique used to separate gold from a mixture of sand and gravel.
What properties of gold allow it to be separated from sand and gravel by panning?
How does gold change from the time it is collected to the time it is ready to sell?

2. Physical Properties
Physical property: any characteristic of a material that you can observe or attempt to observe without changing the identity of the material
Appearances: How does it look? (color, shape, size, texture, state of matter)
Behavior: What can it do? (malleability, ductility, magnetism, viscosity, melting point, boiling point, density)
Example: Describe an object in the room.

3. Physical Change
Physical change: any change in size, shape, or state of matter in which the identity of the substance remains the same
Examples: boiling, freezing, evaporating, condensing
Physical properties and physical changes can be used to separate mixtures
Distillation: process that can separate two substances in a mixture by evaporating a liquid and recondensing its vapor

4. Distillation

5. Using Physical Properties to Separate
How could you separate a mixture of sand, sugar and iron filings?
Use a magnet to remove the iron filings from the mixture.
Add water to the sand and sugar that remains.
Use filter paper to separate the sand from the sugar and water (the sugar is dissolved in the water and will pass through the paper).
Distill the water, leaving the sugar behind.

6. Chemical Properties
Chemical property: any characteristic of a substance, such as flammability, that indicates whether it can undergo a certain chemical change
Examples: flammability, reaction to light

7. Chemical Change
Chemical change: a change of one substance into a new substance
Examples: burning, rusting, tarnish
Clues that you are witnessing a chemical change: heat, cooling, light, sound, bubbles in a liquid (gas), formation of solids in a liquid (precipitates), smoke (NOT steam!)
The ultimate evidence: a new substance has formed

8. Using Chemical Change to Separate
Removing tarnish from silver jewelry
Tarnish is silver sulfide; formed from sulfur compounds in the air
Tarnish can be changed back to silver!

9. Physical or Chemical Change?
First ask: is the _____ still a _____ ?
Melt a block of ice
Bake a cake
Crush a can
Bend a spoon
Burn wood
Freeze a fish
Frying potatoes
Processing a deer
Rust

10. Physical or Chemical Change?
First ask: is the _____ still a _____ ?
A dog growing its winter coat
Digestion
Ripping paper
Photosynthesis
Decomposition
Lighting a Bunsen burner
Growing flowers
Dissolving sugar into water
Weathering of rock

11. The Law of Conservation of Mass
The mass of all substances that are present before a chemical change equals the mass of all the substances that are remaining after the change
Example: burning wood
All that is left after combustion is a pile of ashes—much smaller, isn’t it?
The mass of the log PLUS the oxygen used during combustion IS EQUAL TO the mass of the ashes PLUS all the smoke (carbon dioxide, water vapor, unburned particles) given off during the reaction