1. Entropy (?)

2. What is entropy ? A count of the number of equivalent states of a system Equivalent ? States ??

3. Entropy

4.  S < 0

5. Entropy

6.  S < 0

7. Entropy

8.  S > 0

9. Bonding/Assembly Bond Energy vs. Thermal Energy

10. What is Energy? Capacity to do Work. … What does this mean? Energy Stored (Potential) Chemical Nuclear Magnetic Electrostatic Mass EM Radiation Light X-rays microwaves Motion (Kinetic)

11. Energetics of an Explosion TNT In what form is the energy?

12. Energetics of an Explosion Bang! In what form is the energy?

13. Potential Energy U (or E)

14. F

15. Force, Energy and Bonding

16. A B

17. Free Energy Enthalpy and Entropy

18. Potential Energy x E b =bond energy x Transition State EbEb 0 E activ.

19. x Bonding / Assembling

20. x Disassociating

21. Potential Energy x EbEb x 0 Bonding / Assembling

22. Potential Energy x EbEb x 0 Disassociating

23. Effects of thermal energy on Bond Strength Potential Energy x EbEb kBTkBT Thermal Energy affects the Dissociation Constant and Bond Strength. Thermal Energy aids the dissociation of a bond. 0

24. Bond Strength: Boltzman Factor What is the probability that a bond will spontaneously dissociate???? P=e -E b /kT kT at room temperature = 0.025 meV The rate of dissociation r d  e -E b /k B T Attempt frequency Vibrational frequency of bond or inverse relaxation time Probability per attempt Rate of dissociation

25. Force, Energy and Bonding

26. A B  U = U B –U A < 0 Spontaneous & Stable

27. Gibbs Free Energy G  S Thermodynamic Potential Helmholtz Free Energy F  U  S TempEntropy Enthalpy U + PV Potential Energy (chemical typically)

28. Thermodynamic Potential Helmholtz Free Energy F  U  S  F =  U - T  S When change in free energy is negative, process is spontaneous Define System

29.  F =  U – T  S  U = ? > or < 0 ?  S = ? > or < 0 ? When change in free energy is negative, process is spontaneous

30. Bond Strength: Boltzman Factor What is the probability that a bond will spontaneously dissociate???? P=e -E b /kT kT at room temperature = 0.025 meV The rate of dissociation r d  e -E b /k B T Attempt frequency Vibrational frequency of bond or inverse relaxation time Probability per attempt Rate of dissociation

31.  U > or < 0 ?  S > or < 0 ?  F =  U - T  S

32.  U > or < 0 ?  S > or < 0 ?  F =  U - T  S

33. A B C D E Which representative state of the fiber has highest entropy?