Transcript Chemical Changes

AIM:What are chemical and physical changes?
What are chemical and physical
changes?
AIM:What are chemical and physical changes?
Differentiate the meaning of
chemical change and physical
change
AIM:What are chemical and physical changes?
Chemical change
Physical change
AIM:What are chemical and physical changes?
Investigate:
Crumble a piece of paper
Rip a piece of paper
Burn a piece of paper
What are the differences?
AIM:What are chemical and physical changes?
List some examples of
Physical Change
1. cutting, freezing, boiling
2. does NOT produce a new
substance
3. Commonly associated with the
phase change diagram
4. Solid liquid gas
AIM:What are chemical and physical changes?
What Exemplifies a Chemical
Change?
1. Materials combine to form a new
substance
2. Burning paper
3. Rusting Iron
AIM:What are chemical and physical changes?
Digestion has both Physical and
Chemical Changes
1. Chewing of food by teeth into
smaller pieces
2. Stomach/Small Intestine breaks
down food into individual
molecules (fats, sugars, amino
acids)
AIM:What are chemical and physical changes?
Definition
• Chemical change: The substances present
at the beginning of the change are not
present at the end; new substances are
formed. The change cannot be “undone.”
AIM:What are chemical and physical changes?
Examples
• Physical Changes
• Aluminum foil is cut in
• Clay is molded into a new
shape.
• Butter melts
• Water evaporates from
the surface of the ocean.
• a juice box in the freezer
freezes.
• .Rubbing alcohol
evaporates on your hand
•
•
•
•
•
Chemical Changes
Milk goes sour.
Jewelry tarnishes.
Bread becomes toast.
Rust forms on a nail left
outside.
• Gasoline is ignited.
• Hydrogen peroxide
bubbles in a cut.
AIM:What are chemical and physical changes?
AIM:What are chemical and physical changes?
Name at least 5 clues that would
indicate there has been a chemical
change in matter.
1. color
2. energy change
3. odor
4. Gas or precipitate (solid) produced
5. not easily reversed
AIM:What are chemical and physical changes?
Odor Change
AIM:What are chemical and physical changes?
Color Change
AIM:What are chemical and physical changes?
Energy Change
AIM:What are chemical and physical changes?
Precipitate
AIM:What are chemical and physical changes?
Not easily reversed
AIM:What are chemical and physical changes?
PHYSICAL CHANGES
MELTING
• solid to liquid
• As the ice gains
energy – more
molecules vibrate
• eventually the
bonds that form
the ice crystals
break and the ice
melts.
FREEZING
• the reverse: looses
thermal energy
• The molecule
move about more
slowly
• Eventually the ice
crystal start to
form
AIM:What are chemical and physical changes?
Vaporization
EVAPORATION
BOILING
• Water slowly gains • Water rapidly
energy
gains energy
• Gradually
• Quickly converts
converts to gas
to gas
• “sweating”
Reverse of Vaporization is called
CONDENSATION
AIM:What are chemical and physical changes?
SOLID > GAS
SUBLIMATION
Dry Ice
AIM:What are chemical and physical changes?
Practice Quiz
• http://www.mrzimmerman.org/OnLineQuiz
Page/Chem%20Practice.htm
AIM:What are chemical and physical changes?
REVIEW VOCABULARY –
AIM:What are chemical and physical changes?
Class Activity:
Worksheets Concepts 12-4
AIM:What
are chemical
and physical
changes?
AIM: What
are habitats
and niches?
Homework:
INTERNET QUESTIONS
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