1. CHEMICAL REACTIONS
8.5E – Investigate how evidence of a chemical reaction indicate that a new substance with different properties has formed

2. CHEMICAL REACTIONS: Elements can combine to form new substances
Substances can be broken down into simpler substances
Atoms are re-arranged NOT created or destroyed

3. CHEMICAL REACTIONS: Formulas and equations express what happens
What is written is a recombination of those atoms
Ex. O2 + 2H2O H2O
This “rearrangement” shows that new substances with new properties has been formed

4. Remember: Law of Conservation
Mass of Reactants = Mass of Products

5. CHEMICAL CHANGES A change that produces new substances
Properties of the substances change

6. Signs (Evidence) of a Chemical Change
Gas is formed/released
Change in odor
Change in temperature
A precipitate forms
Light is produced (flame, bioluminescence, glow sticks, explosions)
Change in color (unexpected)
Sound

7. Common Misconception Alert!
Temperature change due to adding or removing heat does not represent a chemical change.
For example, melting or freezing is a change of state which is a chemical change.

8. Specific examples that a chemical change has occurred:
GAS- baking soda and vinegar
COLOR CHANGE- rust
HEAT- fireworks (combustion)
SOLID- lead nitrate + potassium iodide = lead iodide (a precipitate)

9. Gas is Formed
Elephant’s Toothpaste

10. The batteries split the H2 and the O.
Gas Production
Flammable Water
Water = H2O.
The batteries split the H2 and the O.
H2 = hydrogen.

11. Change in Color
Steve Spangler – Color Change

12. Change in Odor
Rotten Egg Lab

13. A Precipitate is Formed
Golden Rain
Golden Rain Part 2

14. Light is Produced
Surprize Fire

15. Change in Temperature
X on Fire!
Thermite Reaction

16. Several Examples in One
Multiple Reactions

17. HW: Read through the “Chemical Reactions” packet.
On the last page is a table to complete. Use the reading to help you fill in this table.
Due next class

18. Now let’s observe a chemical reaction!
This is the student version of notes – what reaction we are doing is a surprise – you will just have to come class !