1. Chemical Reactions and Equations

2. Chemical Reactions
Chemical bonds are broken and reformed creating new substances
Cellular respiration: glucose and O2 reacting to form energy, CO2 and H2O
C6H12O6 + O > CO2 + H2O + energy
An iron chain rusting
Fe O > Fe2O3
Reactants > Products

3. Balanced Equations
Law of Conservation of Mass : matter cannot be created or destroyed, it just changes forms
Number of atoms of each element on reactant side must equal the number of atoms on product side
Coefficients: Numbers in front of formula; represent number of molecules of substance

4. C6H12O6 + 6O2 ----> 6CO2 + 6H2O + energy
Balanced Equations
4 Fe O > Fe2O3
C6H12O6 + 6O > 6CO2 + 6H2O + energy
Coefficients in red

5. Balanced Equations Try This: CH4 + O2 -----> CO2 + H2O

6. Balance this:
H2O > H2O O2
2H2O > 2H2O O2

7. Energy of Reactions
Activation Energy: amount of energy necessary to start a chemical reaction
In every chemical reaction there is a change in energy due to the breaking and making of bonds.

8. Exothermic Reaction

9. Exothermic Reaction Releases energy- usually in the form of heat
Reactants have more energy than products (products more stable)
Reaction more likely to go forward

10. Exothermic Reaction Activation Energy Amount of Energy released
Products
Reactants

11. Endothermic Reaction

12. Endothermic Reaction Absorbs energy
Reactants have less energy than products (reactants more stable)
Reaction less likely to go forward

13. Enzymes Reactions in living organism occur too slowly Need to speed up
On the energy diagram what will enzymes affect?
Activation Energy

14. Energy Diagram with Enzyme