1. Chemical Properties

2. Learning Goals Identify Chemical Properties
Identify physical and chemical changes

3. Chemical Property
The ability of a substance to change (react) and form new substances

4. Combustibility
This property describes how easily a substance can catch on fire.
Example:

5. Two trees, different combustibilities

6. Light Sensitivity
Some substances are very sensitive to light and actually change into a different substance when exposed to light.
Example: hydrogen peroxide (used as a disinfectant) is sensitive to light and sold in dark brown bottles.

7. Stability The ability of a substance to remain unchanged
The more stable a substance is, the longer it will take to break down
Between water and hydrogen peroxide, which is more stable?

8. Toxicity
The ability of a substance to cause harmful effects in plants and animals
Example: DDT, Carbon monoxide

9. Physical and Chemical Change

10. Remember this question?

11. PHYSICAL CHANGES Physical changes involve a change in state. Gas Solid
Liquid

12. In a physical change,
the substance
DOES NOT become a new substance.
Physical changes can always be reversed

13. Examples:
Dissolving sugar in water
Melting Ice

14. Chemical Changes
A chemical change results to a new substance being created.
Chemical changes are very difficult to reverse.

15. Examples
Lighting a match
Baking a cake
Heartburn medication

16. Example: Combustion
Combustion occurs when heat is applied to a chemical.

17. Example: Rusting
Rusting occurs when metals such as iron react with the oxygen gas in the air to form rust.

18. If you make two or more of the following observations then a chemical change has probably taken place:

19. The starting material is used up
Heat is produced (feels warm)
or absorbed (feels cold)
The colour changes
Gas bubbles form in a liquid
Grains of solid precipitate form in the liquid

20. Class work Read pages 160 to 164 Do page 165 # 1, 2, 3, 5 Worksheets
Physical and Chemical Properties
Physical and Chemical Changes