1. Class Opener: Tuesday, September 10
Distinguish between a physical change and a chemical change.
Is the burning of gasoline is considered a physical or chemical change? the evaporation of gasoline? Explain reasoning of each of your choices.

2. Changes in Matter
Physical Change – change that does not alter the identity of the substance.
Changes in appearance only.
All state changes are physical changes.
Ex: tearing paper and ice cube melting
Chemical Change – Change in which one or more substances are converted into new materials with different properties. (chemical reaction)
Ex: burning paper and iron rusting

3. Its Your Turn!
Determine if each of the following represents a chemical change or a physical change.
Grinding chalk into a powder
Digesting food
Paper towel absorbs water
Evaporation of alcohol
Piece of jewelry turns skin green
Sublimation of dry ice
Making hydrogen gas from water
Frying a hamburger

4. Signs of a Chemical Reaction
How can we tell if a chemical reaction has occurred?
Production of a Gas
Color Change (usually)
Evolution of Energy (heat and/or light)
Formation of a precipitate
precipitate – A solid that forms when
mixing two liquid solutions

5. Energy and Changes in Matter
Whenever a physical or chemical change occurs energy is always involved.
Exothermic – Process in which energy is released.
Ex: Burning paper
Endothermic – Process in which energy is absorbed.
Ex: Melting of an ice cube

6. One Minute Paper
You have one minute to answer these two questions concerning today’s lesson.
What was the most important thing you learned?
What is still muddy? 6