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Physical

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Law of conservation of mass. Mass is neither created nor destroyed ... Electrolysis of water. Chemical Change Evidence. Formation of a gas ... – PowerPoint PPT presentation

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Title: 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
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