Warm-Up

1
Warm-Up

• Please sit down quickly and quietly.
• Please copy down the schedule in your Raven Book.
• Next, answer this Warm-Up Question on your yellow
  sheet
• Explain what you think is a physical property.
  Name five physical properties of your desk.

2
Physical vs. Chemical Changes
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Goal How do you tell the difference between
chemical and physical changes?
4

• Physical Change
• A change in any objects physical properties
• any change in an objects
• - mass - color
• - weight - shape
• - volume - hardness
• - density - texture

5
Physical Changes

• Changes in Density, Mass or Volume D M/V

6
Physical Changes

• Creating mixtures that can be separated out -
  mixtures can be reversed.

7
Physical Changes

• Changes in Phase of Matter

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Example of a Physical Change
A Melting Icicle
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• physical properties characteristics of a
  substance that can be observed without changing
  the identity of the substance.
• ex.) wood is still wood whether it is shaped
  into a baseball bat or used to build the walls of
  your house or if its still in the shape of a
  tree!
• ex.) water is still water whether it is in the
  form of ice, liquid water, or water vapor. Its
  still H2O!

10
Review Other Physical Properties

• Color
• Size
• Shape
• Texture
• Magnetism

11
Chemical Changes

• Chemical Changes occur when atoms react with
  other atoms to form chemical bonds.
• When atoms are bonded together they make a
  molecule.

12
Chemical Changes

• When a chemical reaction happens the new
  molecules are a new substance or compound.
• A B ? AB

13

• Chemical Change
• gt changes that substances undergo when they turn
  into other substances
• gt Also called a Chemical Reaction
• ex.) as coal burns, O2 (in the air) combines
  chemically with C (the substance that makes up
  most of the coal) and forms a completely new
  substance CO2
• - C and O2 have changed chemically! They
• no longer exist in their original
  forms!
• - Written out C O2 CO2

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Evidence of Chemical Changes, Reactions or Bonding

• Energy being taken in or given off (heat,
  coolness, light)

15
Evidence of Chemical Changes, Reactions or Bonding

• Gas or Bubbles

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Evidence of Chemical Changes, Reactions or Bonding

• Color or Texture Change

17
Evidence of Chemical Changes, Reactions or Bonding

• Color and Texture Change that is not easily
  reversed

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Evidence of Chemical Changes, Reactions or Bonding

• Forming of a Precipitate (adding to solutions and
  a solid is formed)

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How to decide type of change

• Ask yourself Can I easily turn substance back to
  the way it was?
• If yes physical change
• If no chemical change
• Was the change awesome to watch?
• If yes Probably chemical change
• If no Probably physical change
• Did the name of the new substance change?
• If yes Probably chemical
• If no Probably physical

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Examples of Chemical Change

• The rusting of iron
• The baking of bread
• Burning of a match
• Fireworks

21
Example of a Chemical Change The Electrolysis
of Water (H2O)
The Chemical Identity of Water ( H2O ) is changed
into the elements Hydrogen ( H2 ) and Oxygen ( O2
)
22
Homework Complete in notebook
Physical or chemical change with explanation
Sugar water
Frying an egg
Whipping egg whites
Melting of dry ice
Burning gasoline
Boiling water
Breaking glass
Souring milk
Sun tanning
Boiling coffee
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Copy the chart below for the lab tomorrow ? (you
need 10 rows)
Station Substances combined Observations Physical or Chemical Change
1
2
3
4
5
6
7
8
9
10
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Station 1

• Step 1 measure 1 gram of baking soda and put it
  into the 100 ml beaker
• Step 2 measure 1 mL of vinegar
• Step 3 pour the 1 mL of vinegar into beaker
  with baking soda
• Step 4 observe what happens and record
  observations and inference about whether you
  think it is a physical or chemical change
• Step 5 clean up rinse out the beaker and
  graduated cylinder in the sink

25
Station 2

• Step 1 take a sheet of paper and drop it on to
  the ground how many seconds does it take to hit
  the ground?
• Step 2 now crumple up the paper into a ball.
• Step 3 drop the paper ball from the same height
  you dropped the flat paper how many seconds
  does it take for the crumpled ball to hit the
  ground?
• Step 4 observe what happens and record
  observations and inference about whether you
  think it is a physical or chemical change
• Step 5 clean up

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Station 3

• Step 1 take a tarnished penny and try to clean
  it with soap and waterdoes it work?
• Step 2 now try to clean it with a few drops of
  lemon juicedoes it work?
• Step 3 rinse and dry the penny and try to clean
  it with water and saltdoes it work?
• Step 4 now use a a few drops of lemon juice and
  a dash or two of salt to try to clean the penny
• Step 5 observe what happens and record
  observations and inference about whether you
  think it is a physical or chemical change
• Step 6 clean up, rinse and dry the penny and
  put the penny in the plastic container on the
  counter

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Station 4

• Step 1 take a the 100 mL beaker and fill it
  with water from the sink.
• Step 2 take one spoon full of table sugar and
  put it in the beaker with water.
• Step 3 stir the sugar in the solution until
  dissolved.
• Step 4 observe what happens and record
  observations and inference about whether you
  think it is a physical or chemical change
• Step 5 clean up rinse out the beaker

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Station 5

• Step 1 put 50 ml of water into the beaker
• Step 2 drop 2 3 drops of food coloring into
  the water (one drop at a time) and watch
• Step 3 observe what happens and record
  observations and inference about whether you
  think it is a physical or chemical change
• Step 4 clean up rinse out the beaker

29
Station 6

• Step 1 measure out 10 mL of milk and pour into
  beaker
• Step 2 in a different graduated cylinder
  measure out 2 mL of vinegar and pour into the
  beaker with milk
• Step 3 stir the milk and vinegar together
• Step 4 observe what happens and record
  observations and inference about whether you
  think it is a physical or chemical change
• Step 5 clean up rinse out the beaker and
  graduated cylinder in the sink