Warm-up

1
Warm-up

• What does it mean to change something?

2
Changes

• Physical vs. Chemical

3
Physical Changes

• No NEW substances are made!
• It is a change that doesnt alter the substance,
  only one of its physical properties
• Reminder a physical property is something you
  can observe without changing an object like
  volume, color, mass, density, etc.

4
Examples

• Read page 88 and write down 3 examples of
  physical changes

• Ice freezing
• Wood sanded
• Sugar dissolving
• What else do you have?

5
Reversibility

• You can reverse a physical change and return the
  substance back to its original state most of the
  time.

6
Chemical Change

• NEW substance is made!
• This is when one substance reacts with something
  else to turn into a new material with its own
  unique properties
• Key words for identifying a Chemical Change
  (useful when the questions uses chemicals that
  you have never heard of!)
• Reacts
• Decomposes
• Produces
• Neutralizes

7
Examples

• Look at the pictures on page 92 and write down 3
  examples of chemical changes

• Soured milk
• Effervescent tablets fizzing
• Statue of Liberty turning green
• Cake baked. Batter is a different substance than
  the finished baked cake!
• What else do you have?

8
How can you tell a Chemical Change has occurred?

• Color change
• Odor change
• Producing Gas
• Fizzing and/or foaming
• Sound is produced
• Light is produced
• Temperature changes
• Precipitate forms (solid from the combination of
  2 liquids!)

9
How can you tell a Chemical Change has occurred?
(Examples)

• Color change ? Bleach on jeans
• Odor change ? Milk sours
• Producing Gas ? Airborne medicine releasing gas
• Fizzing and/or foaming
• Sound is produced ? Snap rocks/ campfire
• Light is produced ? Glow stick glowing
• Temperature changes ? Campfire
• Precipitate Forms ? Milk chunks from milk and
  vinegar mixing.

10
NO Reversibility

• In a chemical change, the change usually CANNOT
  be reversed, it is permanent.
• These changes can only be changed through more
  chemical means.

11
Chemical Changes continued!

• Chemical Changes always involve physical changes,
  however they are only identified as a chemical
  change.
• What does this mean?
• When you bake a cake it will change state (liquid
  to solid) however it also releases gases.
• Chemical Changes trump physical changes! ?
• (Chemical always wins!)

12
Venn Diagram Assignment

• Create a Venn Diagram to compare and contrast
  physical and chemical changes
• You must include
• 2 pictures of each type of change
• 15 facts
• At least 5 on each side and 3 in the middle,
  final 2 you get to choose
• Due Thursday/Friday!