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Aim: How are physical and chemical changes different?

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Aim: How are physical and chemical changes different? Aim: Look at the picture below. List as many properties of the object in the picture as you can. – PowerPoint PPT presentation

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Title: Aim: How are physical and chemical changes different?


1
Aim How are physical and chemical changes
different?
  • Aim Look at the picture below. List as many
    properties of the object in the picture as you
    can.

2
What is a physical property?
  • Properties that can be observed without the
    production of new substances. These properties
    include
  • Color, shape, phase, solubility (does it
    dissolve), density, melting point, boiling point,
    hardness, taste, weight, conductivity,
    malleability (does it bend), ductility (can it be
    made into a wire), volume, mass, etc
  • A physical change is a change in the physical
    characteristics of the sample. Physical changes
    can be reversed.

3
What is a chemical property?
  • The ability to undergo a specific chemical
    change. Chemical properties can only be observed
    during a chemical change. During a chemical
    change, the composition of matter always changes.
    These changes cannot be reversed by ordinary
    means. Chemical changes are also known as
    chemical reactions.

4
Part of a Chemical Reaction
  • Reactant the substance that is present at the
    beginning of the reaction.
  • Product the substance produced as a result of
    the reaction.
  • Example
  • Baking Powder Vinegar ?Water Carbon Dioxide
  • Reactants Products

5
How can we recognize whether a chemical change
has occurred?
  • Signs to look for
  • The transfer of energy (heat has been released or
    absorbed).
  • A change in color.
  • The production of a gas.
  • The formation of a precipitate (a solid that
    forms and settles out of a liquid mixture).

6
A Demonstration
  • Which sign is released by each reaction that
    tells you if it is a chemical reaction?

7
Activity
  • Complete the worksheet you were given.

8
Homework
  • Read pages 75-77 Sections 4-7 and 4-8.
  • Copy and answer 21 and 22 page 78
  • Copy and answer 21-25 page 82.
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