Chem.412 – Molecular Energies

1. Chem.412 – Molecular Energies HyperChem

2. Equipartition of Energy – Model of Molecular Motions • Different Motions; Different Energies • View molecule as “group” of mass points • For N atoms, 3N degrees of freedom (DOF) • Translational, Rotational, Vibrational. HyperChem DQ

3. Equipartition of Energy Boltzmann constant: k = 1.38066x10-23 J K-1 DQ HyperChem

4. Equipartition of Energy HyperChem DQ

5. Classical Energies Etot = ∑ ½kT for each square-term

6. Equipartition of Energy Boltzmann constant: k = 1.38066x10-23 J K-1 DQ HyperChem

8. HyperChem DQ

9. Experimental Measures of Molecular Energies • Spectroscopy: • IR (vibrational energy) • Microwave (rotational energy) • Molecular Beam (translational energy) • Heat Capacity: Heat Capacity is the ability of the substance to store energy.

10. Molecular Energies: Cv and ∆U

14. Molecular Energies: Cv and ∆U – F12

16. Area Under the Curve: Trapezoidal Rule Mathcad

17. Area Under the Curve: Trapezoidal Rule Mathcad

18. Area Under the Curve: Integration

19. Area Under the Curve: Integration of Cv

20. Area Under the Curve: Integration – F12 Mathcad13

21. Area Under the Curve: Integration of Cv -F12

23. Cvm Comparisons

24. Cvm Comparisons

25. Chem.412 – Molecular Energies

26. Equipartition of Energy