1. 3.6 Physical and Chemical Changes

2. Law of Conservation Demo!
Calcium Chloride + Sodium Carbonate
Later – Styrofoam +Acetone

3. Chemical Change
A chemical change is any change where you change a substance chemically.
A new substance is created
Example: Lighting a match

4. Evidence of a Chemical Change
Chemical Changes occur when:
…there is a change in color
… there is a production of gas (bubbles)
… there is a formation of a precipitate
precipitate – a solid produced by the chemical reaction between two solutions.
… there is a production of heat and light

5. Examples of Chemical Change
Burning
Tarnish
Oxidation/Rusting

6. Physical Changes
Physical Change- a change that takes place that does NOT change the substance chemically. Examples: haircut, ice melting, distillation, phase change

7. Phase Changes
A phase change is a reversible physical change that occurs when a substance changes from one state of matter to another.
Energy is either absorbed or released during a phase change.
Endothermic – energy is absorbed
Exothermic – energy is released

9. Weathering Physical – Freezing and expanding Chemical – Acid rain
dissolving limestone
(calcium carbonate)

10. Law of Conservation of Mass
The mass of all substances that are present before a chemical change equals the mass of all the substances that remain after the change.