Physical and Chemical Changes

1. Physical and Chemical Changes How to tell the difference

2. Physical Change- • physical properties change, but the substance is the same • Change in what you see but does not produce a new substance • Painting a house, cutting hair, ironing shirt, melting water/boiling water

3. Some physical changes are reversible, some are not • Reversible—freezing & melting water, braiding hair • Non-reversible—slicing a tomato, peeling an orange

4. Indicators of a Physical Change

5. It’s a physical change if • It changes shape or size • It dissolves.

6. It’s a physical change if... • It changes phase (freezes, boils, evaporates, condenses)

7. Chemical Change • Chemical Change- • when substances react to form one or more NEW substances • Look for permanent change in color, gas bubbles, leftover solid • Non-Reversible

8. Indicators of a Chemical Change

9. It’s a chemical change if…. • It burns • Temperature changes without heating/cooling

10. It’s a chemical change if... • It bubbles (makes a gas)

11. It’s a chemical change if... • It changes color permanently • It forms a leftover solid

12. Examples: • Silver ring that turns green • Rusting cars • Copper pennies turning green • Baking powder in cake – cake rises • Vinegar and baking soda • Adding vinegar to milk • Lighting a match • Explosion or burning of wood

13. What kind of change is it if someone... • Tears up paper? • Physical change • Mixes salt and water? • Physical change

14. What kind of change is it if someone... • Burns paper? • Chemical change • Evaporates salt water? • Physical change