Post on 23-Feb-2016
description
Do Now 11/4/10What will happen to the
dollar? Why?
Matter can be changed in 2 ways
Physical ChangesChemical Changes
What are Physical Changes?
Physical Changes:1) Atoms do not rearrange2) Generally easy to reverse.3) Only physical properties change.
Sign of a Physical Change
Change in:1.Color
2.Mass
3.Volume
4.Density
More Examples…5. Size
6. Luster or “Shine”
7. Shape
And More Examples….8. Texture (the feel of
something)
9. State of matter (Solid, Gas, or Liquid)
Guess that Change
Grinding Wood on a spinning saw
Is the composition of this wood changing?
What IS changing?
What changes?
Wrecking a car
Melting ice cream…
What is changing?
Bending Wire…
What is changed when we bend it?
Chemical Changes
1) Atoms DO rearrange.2) CANNOT be reversed.3) Something entirely new is created. 4) Chemical Formula changes
-Reaction with Oxygen in the air
Examples:
• Rust (cars, apples)
• Tarnish (jewelry)
• Statue of Liberty
Oxidation
The Statue of Liberty, 1886
The Statue of Liberty, 2010…
What happened?
This boat has OXIDIZED!
-Flames produce black ash
Examples:• Wood burns and turns to ash• Water does not burn
The Burning Dollar exampleRevisited
Describe the physical properties of the two ingredients.
Now, describe the chemical properties of the two ingredients.Which ingredient is flammable?Which ingredient is NOT
flammable?
Now, use your new science knowledge to explain the science behind the experiment!
Combustibility-Reaction with fire and produces CO2 gas.
ExampleMetal car burning.
Black smoke (CO2 gas) is released.
Reacts with acid and produces gas bubbles or heatExample: Baking soda + Vinegar
Example of a Penny reacting with acid…
Penny + Nitric Acid
Formation of a Precipitate (Powder)
Example
Adding colorless sodium chloride to colorless silver nitrate produces a white precipitate.
SummaryPhysical Changes -Don’t produce something new - are reversible. Chemical changes -Produce something new-Change the identity of the raw materials-Are irreversible-Are exciting to watch!