1. What are Chemical and Physical Changes?

2. Evidence of a Physical Change
There are three signs that a physical change has occurred (remember, this means that your starting and ending molecules are the same)
Change in size
Change in shape
Change or phase

3. Evidence of a Chemical Change
There are five signs that a chemical change has occurred (remember, this means that your starting and ending molecules are different)
Change in Temperature, giving off heat
Change in Color, giving off light
Change or Creation of Odor
Formation of a Precipitate (a solid material)
Formation of a Gas

4. THE DIFFERENCE
Physical Change – matter changes form but is still made of the same molecules, typically reversible
Chemical Change – a change in the molecules occurs, cannot be reversed

5. Physical Changes
Physical Change – matter changes form but is still made of the same molecules, typically reversible
Example:
An ice cube melting
Solid H2O  Liquid H2O
Both the beginning and ending products are made of H2O, the molecules stayed the same

6. Physical Changes
Physical Change – matter changes form but is still made of the same molecules, typically reversible
Example:
A bag of potatoes is
squished up to make
mashed potatoes

7. Physical Changes
The digestive system is very muscular and causes physical changes starting with chewing and continuing with churning in the stomach

8. Chemical Changes
The digestive system also causes chemical changes by using enzymes and chemicals to break the food down into its components

9. The Difference
Physical Change – matter changes form but is still made of the same molecules, typically reversible
Chemical Change – a change in the molecules occurs, cannot be reversed

10. Chemical or Physical Change?

11. Chemical or Physical Change?

12. Chemical or Physical Change?

13. Chemical or Physical Change?

14. How to Separate Mixtures
If you have a solution, you can separate out the different parts using chemical or physical methods.

15. Physical Separation
Physical separation techniques use the physical properties of the components to separate them.
Physical properties include:
State of matter (solid, liquid, gas)
Solubility
Boiling point
Melting point
Density
Electrical/magnetic properties

16. Chemical Separation
Chemical separation requires that you change one of the molecules in order to remove it from the mixture/solution.