1. Bell Ringer
A change in a substance that does not change the substance’s identity is a _________ change.
What is an example of #1?
A change in a substance that causes that substance to break and form a new substance is a ________ change.
What is an example of #3?

2. #1- Identify the steps of the scientific method
ALCOS Objectives:
#1- Identify the steps of the scientific method
#4 State the law of conservation of matter (Balancing Chemical Equations)

3. Types of Chemical Reactions

4. Types of Chemical Reactions
1. SYNTHESIS – two or more substances combine to form one compound
Example: 2 Mg + O > 2 MgO

5. 2. DECOMPOSITION – One substance breaks down into 2 or more elements or compounds
Example: 2 H20 --- 2 H

6. 3. REPLACEMENT OR DISPLACEMENT reactions- When one or more elements replace one another
Ex: Zn + 2 HCl ---- ZnCl2 + H2

7. Copy and tell if it is a synthesis, decomposition, or displacement
1. 2CO + O2 ---- 2CO2
2. 4Fe + 3O2 --- 2 Fe2O2
3, 2H2O2 ---- 2H2O + O2
4. 2KBr + Cl2 ---- 2KCl + Br2
5. C6H6 + Cl2--- C6H5Cl + HCl

8. 6. Zn Cl2 ----> Zn + Cl2
7. 4H2 + Fe3O4 -- 3Fe + 4H2O
8. AgNO3 + NaCl -- AgCl + Na NO3
9. Mg + 2HCl -- MgCl2 + H2

9. Endothermic and Exothermic Reactions
1. the burning of carbon
C + O2 ---- CO2 + energy
2. the formation of salt
Na + Cl --- NaCl + energy

10. Endothermic Reactions
Photosynthesis in plants
6CO2 + 6H20 + energy -- C6H12O6 + O2
The breakdown of water into hydrogen and oxygen
2H2O + energy ---- 2H2 + O2

11. Choose endothermic or exothermic for each example:
1. oil is burned
2. an electric eel shocks its prey
3. a cake bakes
4. someone strikes a match
5. a flashbulb flashes on a camera
6. dead plant material decays, producing warm compost

12. 7. fireworks explode
8. clay turns into brick when it is heated in a kiln at high temperatures
9. chemical reactions occur in a battery
10. a firefly flashes its light

13. Answer key: 1. exo. 2. exo. 3. endo. 4. exo. 5. exo. 6. exo. 7. exo.