2. 1 Chemical Thermodynamics

3. 2 kinetics (little k): told us how fast a RXN would go and indicated a mechanism. Equilibria (big K): told us to what extent a RXN would occur. Themo: the energy involved and if a RXN WILL occur as written.

4. 3 3-Laws of Thermo. 1st: Energy is conserved. Enthalpy (H), for a Rxn @ constant pressure the enthalpy change equals the heat transferred between the system and the surroundings. 2nd : A system not @ Equilibrium will move in a natural (spontaneous) direction. ENTROPY....(S or  S)....disorder. Disorder has a positive sign (+) S of the universe is increasing (Entropy is not conserved) 3rd : S @ absolute zero of a pure crystalline material = 0. (S = 0 @ 0 K) total order.

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6. 5 spontaneous process: a process that is capable of proceeding in a given direction, as written, without needing to be driven by an outside energy. No rate is implied.

7. 6 1st Law of Thermo. (energy is conserved)  E sys =  E surroundings  E = q + w work done on (+) or by (-) the sys. heat gained (+) or lost (-) the sys. internal energy - both kinetic and potential of the sys Review Chapter 5 Expansion work: GASES w = -P  V = force x distance

8. 7 Enthalpy: H and  H (heat transferred in or out or a system) A State Function

9. 8 Spontaneous Processes: Have a definite direction in which they will occur. Examples: H 2 O(s)  H 2 O(l) @ 1 atm and 40 o C H 2 O(l)  H 2 O(s) @ 1 atm and -40 o C Equilibrium: H 2 O(s)  H 2 O(l) @ 1 atm and 0 o C Which process is spontaneous?

10. 9 The direction of a spontaneous process can depend on temperature: Ice turning to water is spontaneous at T > 0  C, Water turning to ice is spontaneous at T < 0  C. A process that is spontaneous in one direction is not spontaneous in the opposite direction.

11. 10 Reversible and Irreversible Processes: A reversible process is one that can go back and forth between states along the same path.

12. 11 Reversible and Irreversible Processes: A reversible process is one that can go back and forth between states along the same path. –When 1 mol of water is frozen at 1 atm at 0  C to form 1 mol of ice, q =  H fus of heat is removed. –To reverse the process, q =  H fus must be added to the 1 mol of ice at 0  C and 1 atm to form 1 mol of water at 0  C. –Therefore, converting between 1 mol of ice and 1 mol of water at 0  C is a reversible process. Allowing 1 mol of ice to warm is an irreversible process. To get the reverse process to occur, the water temperature must be lowered to 0  C.

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