1. Physical and Chemical Changes
Unit II—Part 2

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

3. Physical Change
Physical change: a change that occurs that does NOT change the substance
Usually Reversible

4. Examples of Physical Change
Melting ice (change in state)
Freezing Kool-Aid
Tearing paper
Breaking Glass

5. Chemical Changes
Chemical change: a change that occurs causing the substance to change
Is NOT reversible
A chemical change is called a chemical reaction

6. Examples of Chemical Changes
Burning
Digesting food
Reacting with other substances

7. Chemical Changes Cont’d
Signs of a chemical change:
Light
Heat
Gas
Colour change*
Formation of a precipitate
(solid made from mixing 2 liquids)

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

9. References
Investigating Science Pearson 9
Dercho