1. Chemical Reactions

2. Physical Change Alters form and appearance of materials
Melting, dissolving, freezing, separating
Sublimation, deposition

3. Chemical Change A new substance is formed.
Reactant(s) becomes Products
A + B becomes C + D

4. Evidence for Chemical Change
Precipitate - Solid comes out of a liquid
Color Change
Gas Production
Change in Temperature
Change in Properties
- Soft dough to crust

5. Types of Chemical Reactions
Synthesis - A + B becomes AB
Decomposition - AB becomes A + B
Replacement - AB + C becomes AC + B
Double Replacement
AB + CD becomes AC + BD

6. Getting it started Activation energy Every chemical reaction involves
a change in energy.
Exothermic - releases energy
Endothermic - Absorbs energy

7. Rates of Chemical Reactions
Concentration
Surface Area
Temperature
Catalysts - Enzymes
Inhibitors - Nitroglycerin - Dynamite

8. Chemical Equations
Subscripts (next to and below atom symbol) - applies only to the element just to the left of the number.
MgSO3
Coefficients (in front of molecule) - applies to all atoms in molecule (Propane isomers)
2MgSO (CH3)3CH or C4H10

9. Balancing equations
Conservation of Mass - Total mass of reactants has to equal the total mass of the products