UCI Chem 131C Thermodynamics and Chemical Dynamics (Spring 2012)

Lec 05. Thermodynamics and Chemical Dynamics -- The Equipartition Theorum --

View the complete course: http://ocw.uci.edu/courses/chem_131c_thermodynamics_and_chemical_dynamics.html

Instructor: Reginald Penner, Ph.D.

License: Creative Commons BY-NC-SA

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Description: In Chemistry 131C, students will study how to calculate macroscopic chemical properties of systems. This course will build on the microscopic understanding (Chemical Physics) to reinforce and expand your understanding of the basic thermo-chemistry concepts from General Chemistry (Physical Chemistry.) We then go on to study how chemical reaction rates are measured and calculated from molecular properties. Topics covered include: Energy, entropy, and the thermodynamic potentials; Chemical equilibrium; and Chemical kinetics. This video is part of a 27-lecture undergraduate-level course titled "Thermodynamics and Chemical Dynamics" taught at UC Irvine by Professor Reginald M. Penner.

Thermodynamics and Chemical Dynamics (Chem 131C) is part of OpenChem: http://ocw.uci.edu/openchem/

Recorded on April 11, 2012.

Index of Topics:

00:21 - Announcements

02:34 - Diagram: in real molecules, the situation is considerably more complex than the Harmonic Oscillator

03:20 - We have a very high density of translational states that are not, in reality...

03:36 - Diagram: these translational states are nested within rotational states

03:58 - Diagrams (many rotational states)

04:23 - ...we can treat each of these energetic manifolds...

05:45 - What's in this Lecture

05:51 - Your book mainly focuses attention on...

07:27 - Graph 5-13: Here is what happens to Cv as a function of T for a diatomic molecule:

10:04 - Graph 5-13 These are the rotation temperature...

11:08 - Graph 5-13 Here is what happens to Cv as a function of T...

11:37 - The Equipartition Theorum

12:10 - The Equipartition Theorum (with diagram)

13:17 - consider the classical Hamiltonian for a I D harmonic oscillator:

14:16 - now you'll recall that the heat capacity...

15:03 - Example: Formula

15:50 - Graph

16:13 - ...this is also the heat capacity for all monoatomic gases...

18:29 - For a linear molecule...

19:41 - Graph (Translation + Rotation)

20:26 - For a nonlinear molecule...

20:54 - What about for higher temperatures?

22:08 - so following through with the predictions of the equipartition theorem...

23:05 - so for a diatomic molecule...

24:24 - Example: Use the equipartition theorem to estimate...

31:18 - Example: Use the equipartition theorum to estimate... (Part B)

34:36 - Example: (Chart) "Use the equipartition theorum to estimate... (Part C)

38:55 - Calculate Each Term

39:18 - We'll Start with Translation...

39:40 - The translational energy of a classical gas molecule is:

40:15 - ...And a quantum mechanical gas has energies given by the particle-in-a-box model.

40:23 - we'll concentrate attention now on ideal monoatomic gases...

41:27 - consider first a monoatomic gas in one dimension.

43:59 - ...now these energies are very closely spaced. Consider, for example, an argon atom in a box...

45:25 - Log Scale

45:52 - ...if these states are quasi-continuous, we can rewrite this summation...

46:54 - so after integration we have...

47:05 - Example "Calculate..."

48:26 - What would...three dimensional cube?

49:36 - ...in terms of...now we calculate its transitional energy.

50:03 - ...and this yields a very simple expression:

Required attribution: Penner, Reginald Thermodynamics and Chemical Dynamics 131C (UCI OpenCourseWare: University of California, Irvine), http://ocw.uci.edu/courses/chem_131c_thermodynamics_and_chemical_dynamics.html. [Access date]. License: Creative Commons Attribution-ShareAlike 3.0 United States License.