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
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
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
Physical Changes
• The digestive system is very muscular and
causes physical changes starting with chewing
and continuing with churning in the stomach
Chemical Changes
• The digestive system also causes chemical
changes by using enzymes and chemicals to
break the food down into its components
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)
1.
2.
3.
4.
5.
Change in Temperature
Change in Color
Change or Creation of Odor
Formation of a Precipitate (a solid material)
Formation of a Gas
Chemical or Physical Change?
Physical!
Chemical or Physical Change?
Chemical!
Chemical or Physical Change?
Chemical!
Chemical or Physical Change?
Physical!
How to Separate Mixtures
• If you have a solution, you can separate out
the different parts using chemical or physical
methods.
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
Chemical Separation
• Chemical separation requires that you
change one of the molecules in order to
remove it from the mixture/solution.