Physical

1
Physical Chemical Changes
2
Essential Question

• What are the signs that can be used to determine
  whether a physical or chemical change has
  occurred?

3
Fundamental Laws

• Law of conservation of mass
• Mass is neither created nor destroyed
• Amount of stuff in the universe is constant
• Law of conservation of energy
• Energy is neither created nor destroyed
• The amount of energy in the universe is constant
• Changes in form

4
Fundamental Laws

• Einstein
• E mc2
• Law of conservation of mass-energy
• The sum of the amount of energy and mass in the
  universe is constant
• Mass can be converted to energy and vice versa
• Only occurs in nuclear reactions

5
Physical Changes

• Changes that do not result in a change in the
  fundamental components that make that substance
• Do not affect composition of a substance
• State changes
• Freezing/Boiling Water

6
Changes in phases
Gas
Sublimation
Condensation
Deposition
Evaporation
Melting
Liquid
Solid
Freezing
7
Chemical Changes

• Involve a change in the fundamental components
  that make a substance.
• Produce a new substance
• Chemical reaction
• Reactants ? Products
• Electrolysis of water

8
Chemical Change Evidence

• Formation of a gas
• Formation of a precipitate (ppt)
• Change in energy
• Temperature
• Light
• Change in color
• Works sometimes, not always a sure bet.

9
Identifying Changes

• Physical Changes
• Is it a state/phase change?
• Is it the same substance that I started with?
• Chemical Changes
• Is the substance at the end of the change
  different from the substance prior to the change?
• Has composition changed?

10
Practice

• Iron metal is melted
• Iron combines with oxygen to form rust
• Wood burns in air