1. Physical & Chemical Properties Physical & Chemical Changes
Chapter 3
Physical & Chemical Properties
Physical & Chemical Changes

2. Physical Properties
Characteristics of a substance that can be observed without changing the identity of the substance.
Examples include: mass, weight, volume, density, color, shape, hardness, & texture

3. Physical Changes when only the form of a substance changes
example = change in phase like solid ice to liquid water

4. Properties that describe how a substance changes into new substances
Chemical Properties
Properties that describe how a substance changes into new substances
Examples include: flammability, support for burning, and the ease with which it combines with other substances

5. Chemical Changes
During a chemical change, substances are changed into different substances.
In other words, the composition of the substance changes.

6. Chemical changes create new substances that can not be undone.
Physical changes do not change the chemical composition of the substance
Chemical changes create new substances that can not be undone.

7. Evidence of a Chemical Change
Color change
Odor change
Energy change
Formation of a gas or solid
Not easily reversed

8. Color Changes
As in the case of autumn leaves, a change in color is a clue to indicate a chemical change.

9. Color Changes
Perhaps you have found a half eaten apple that turns brown. The reason is that a chemical change has occurred when food spoils.

10. Odor Changes
It only takes one experience with a rotten egg to learn that they smell different that fresh eggs.
When eggs & food spoil, they undergo a chemical change.

11. Energy Absorbed or Released
the release or gain of energy by an object indicates a chemical change

12. Energy is absorbed during chemical changes involved in cooking, like baking a cake

13. Energy Released Energy can also be released during a chemical change.
Fireworks release energy in a form of light that you can see.

14. Reaction of Sodium With ChlorineNa
& Cl
Reaction of Sodium With Chlorine
You can also see that energy is released when in this movie clip sodium & chlorine are combined with water.

15. Production of a Solid
A solid that separates out of solution during a chemical change is called a precipitate.

16. Production of a Gas
The formation of a gas is a clue to chemical changes.
The bubbles of gas that you observed form when an antacid is dropped into water is an example.

17. Physical = Easily reversed
After ice melts into liquid water, you can refreeze it into solid ice if the temperature drops.
Freezing & melting are physical changes

18. Chemical- Not easily reversed
The substances produced during chemical changes however cannot easily change back into the original substances like when you burn wood.

19. Chemical Reactions
Chemical Changes are also called Chemical Reactions.
Chemical reactions involve combining different substances.
The chemical reaction produces a new substance with new & different physical and chemical properties.

20. Law of Conservation of Mass
Matter is never destroyed or created in chemical reactions.
The particles of one substance are rearranged to form a new substance.
The same # of particles that exist before the reaction exist after the reaction.