1. Physical and Chemical Changes

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 identity of the substance.
The substance remains the same substance!
Melting ice (change in state or phase)
Freezing Kool-aid
Tearing paper
Boiling water (same as melting ice)
*Easy to reverse

4. Chemical Changes
Chemical change: a change that occurs causing the identity of the substance to change.
A new substance is formed.
Burning
Digesting food
Reacting with other substances
A chemical change is called a chemical reaction

5. Chemical Changes Continued
Evidence of a chemical change:
Light
Heat
Production of a gas (bubbles)
Colour change
Formation of a precipitate (solid material)
*Difficult to reverse

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