Wednesday, October 9, 2013

Unit 2 Chemistry Day 15: Chemical Changes

Review: What is a physical change?
A change that does NOT create a new substance!!!

BIG Idea: A ­­chemical change is one that changes the way the atoms and molecules are connected and creates a new substance.

Signs of a Chemical Change
A piece of matter is probably going through a chemical change if any of the following things happen:

1) It burns!
Examples: burning wood in a campfire turning into ash. 

2) It changes temperature!
Example: heat rising from the wood burning in the campfire. 

3) It unexpectedly changes color or odor!
                 Examples: wood turning black in the campfire. 

4) It makes gas bubbles.
                Examples: antacid tablet bubbling when making contact with water. 

A chemical change CANNOT be reversed.

Criteria for Success: 
To decide if a change is physical or chemical, here are some EXAMPLES of questions you can ask yourself:

Can it be reversed?

Yes: physical______________
No: _chemical______________

Is something new being created?

Yes: chemical
No: physical

Are there any signs of a chemical change?

Yes: chemical
No: physical

Is it a change in state (freezing, melting, etc.)?

Yes: physical
No: chemical (maybe, need to ask more questions)

Your Own Question: Does it create an odor?

Yes: chemical 
No: physical

Observation #1 - Kool-Aid Pickles

Observation #2 - Gummy Bear in molten potassium chlorate

Observation #3 - Bromine and Alcohol

Observation #4 - Dry Ice Sublimation 

Observation #5 - Bleach Shirts

Observation #6 - Calcium and Fire

Check Yo Self:

2. Watch Brainpop Video:Property Changes and complete review quiz when finished to reach 80% Mastery.

3. Play the Brainpop Game: Matter Sorter.


Step 1 - Identifying physical and chemical changes: Write “P” for a physical change and “C” for a chemical change.         

____1) A match burning
____2) Sawing a board in half
____3) Crumpling a piece of paper
____4) Water evaporating
____5) Rust forming on a swingset
____6) Corn starch dissolving in water
____7) Ice cream melting
____8) Toast turning black from heat
____9) Gas bubbles produced by Alka-Seltzer
____10) Steam coming off a block of ice
____11) Hydrogen and oxygen combining to form water.

Step 2 – Pick a physical change and chemical change from the above. Describe why each is a physical and chemical change.
12) _____________________________________ is a physical change because __________________________________________________________________________________________________________________________________________________________________.
13) _____________________________________ is a chemical change because __________________________________________________________________________________________________________________________________________________________________.

Solids, Liquids, and Gases LW Part 2

Check Yo Self - Answer Key

  1. C
  2. C
  3. D
  4. D
  5. C
  6. A
  7. A
  8. B

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