1. Topic: Potential Energy Curve Do Now: p.26

2. Spontaneous Processes no outside intervention =physical or chemical change that occurs with no outside intervention activation energy However, some energy may be supplied to get process started = activation energy Iron rusting 4Fe(s) + 3O 2 (g)  2Fe 2 O 3 (s)  H = -1625 kJ Combustion CH 4(g) + 2O 2(g)  CO 2(g) + 2H 2 O (l)  H = -891kJ

3. Can you think of others?

4. VIDEO

5. Activation Energy & Reaction

6. Activation Energy = Energy needed to initiate reaction = Energy needed to initiate reaction Energy needed to overcome reaction barrier difference between where reactants start & top of hill Difference between reactants & activated complex

8. Energy Diagram of a Reaction Activated Complex = intermediate formed during conversion from reactants to products Reactants combine to form an unstable complex

9. Potential Energy Curve: Endothermic Products have more P.E. than reactants Start low, end high

10. Potential Energy Curve: Exothermic Products have less P.E. than reactants Start high, end low

11. Have to label 6 energies on curve: reactants & products 1.PE reactants 2.PE products 3.PE activated complex 4.E a forward reaction 5.E a reverse reaction  H

12. Time Time What kind of reaction is represented? PEreactants PE activated complex PE products E a forward rxn E a reverse rxn 40 30 20 10 Enthalpy 

13.  H of reaction 40 30 20 10 Enthalpy 

14. Time Time What kind of reaction is represented? PE of reactants PE of activated complex P.E. of products E a forwardrxn reverserxn 40 30 20 10 Enthalpy 

15.  H of reaction 40 30 20 10 Enthalpy 

16. Catalyst (in the body = enzyme) Substance that increases rate of reaction without itself being consumed – does not participate in reaction Lowers the activation energy for the reaction

17. DOES IT AFFECT ΔH? Catalysts do not affect ΔH