1. Physical and Chemical Changes
Unit 5 Matter—Part II 1

2. Concept of Change
Change: the act of altering a substance. 2

3. 2. Physical Change
Physical change: a change that occurs that does not change the identity of the substance.
Melting ice
Freezing Kool-aid
Tearing paper
Boiling water 3

4. 3. Chemical Changes
Chemical change: a change that occurs causing the identity of the substance to change.
Burning paper
Digesting food
Electrolysis of water 4

5. 4. Chemical Changes
A chemical change is called a chemical reaction. 5

6. 5. Chemical Changes Cont’d
Indicators of a chemical change:
Evolution of light
Evolution of heat
Evolution of a gas
Color change
Formation of a precipitate 6

7. 6. Is it Physical or Chemical?
Change
Physical
Chemical
Melting cheese
Burning wood
Milk souring
Wadding up paper
Bicycle rusting 7

8. THE END