Physical Chemistry I and II

    Assignments and Solutions


Exeriment A: Heat Capacity Ratios

Write-up Format: Short Lab Format

Helpful readings: Engel and Reid, Thermodynamics, Statistical Thermodynamics and Kinetics (1e) ``Equipartition Theorem'' (page 345) and ``Heat capacities'' (section 15.3, pg 362-366).

  1. Calculate gamma for each gas. Report this value with uncertainties.
  2. Compare gamma with the theoretical gamma for an ideal gas. As N2 is a diatomic gas:
    1. Calculate theoretical gamma assuming that rotational modes are fully excited and that vibrational modes do not contribute at all.
    2. Calculate theoretical gamma assuming that rotational modes are fully excited, this time considering that vibrational modes may contribute. To do this, you will need to calculate Cv(vib) from the vibrational frequencies for the molecule in question. (see Engel and Reid, Thermodynamics...., p. 364, eqn 15.41). Vibrational frequencies can be obtained from the NIST web site. (see pchem links). Comment on the magnitude of the deviation of this gamma from the one calculated assuming vibrational modes do not contribute at all.
  3. Discuss any significant deviations of your experimental values from theoretical values.
  4. To convert pressures from mm dibutylphthalate (d = 1.047 g/ml) to mm Hg (d = 13.594 g/ml). This is a straight ratio. Suppose my manometer reading are LOW side = 32.1 cm dibutylphthalate and HIGH side = 74.8 cm dibutylphthalate, and the barometer reading for the day was 722.1 mm Hg.

    The pressure difference between the atmospheric pressure and the bottle is:

    Pdiff = 74.8 cm - 32.1 cm = 42.7 cm dibutylphthalate (dbp, for now)

    or in millimeters: 427 mm dbp

    Converting to mm Hg:

    
                                   1.047 g dbp              1 cm3 Hg   
    Pdiff =  (427 mm dbp)  x  -------------------  x  -------------------  = 32.9 mm Hg 
                                   1 cm3 dbp              13.594 g Hg
    

    Ptot = Patm + Pdiff = 722.1 mm Hg + 32.9 mm Hg= 755 mm Hg = 755 torr.


Exeriment B: Langmuir Adsorption

Write-up Format: Formal Format

Helpful readings: Engel and Reid, Thermodynamics, Statistical Thermodynamics and Kinetics (1e) ``Homogeneous and Heterogeneous Catalysis'' (sections 19.4.5, pages 498-503).

  1. Use Excel to perform your calculations
  2. Graph your data for the Freundlich and Langmuir Adsorption isotherms
  3. Report your values for the Freundlich and Langmuir parameters
  4. Report the surface area, of the charcoal, S.
  5. Discuss whether or not the data are accurately described by each the isotherms.
  6. Comment on the validity and possible problems with each model
  7. Comment on your surface area results


Exeriment C: UV/Vis Spectroscopy

Write-up Format: Formal Report Format

Helpful readings: Engel, Quantum Mechanics and Spectroscopy (1e) ``The Particle in a One-Dimentional Box'' (section 4.2, pages 46-51), ``Solving the Schrodinger Equation in Two Dimensions'' (section 7.2, pages 108-111) and sections 15.5-15.7 (pages 308-313) from the ``Electronic Spectroscopy'' Chapter.

  • Calculations are described in the laboratory handout. You will need to use CAChe to complete this assignment.


Exeriment D: Resonance Energy of Benzene

Write-up format: Short Format.

Helpful readings: Engel, Quantum Mechanics and Spectroscopy (1e) See ``Huckel Rules'' and ``Resonance Stabilization Energy'' in Section 14.7 (see pages 293-296), and consult your organic text.

  • Calculations and questions to answer are described at the end of the laboratory handout. You will need to use CAChe to complete this assignment.

 

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Questions should be directed to Dr. Kimberly Lawler-Sagarin: ksagarin@elmhurst.edu