Physical Chemistry

Chemistry 412-413

Latest news

Other Current Classes:

Physical Chemistry Laboratory


 
 

 

Click on the experiment title to access calculation/writeup.

  • Kinetics of Polymerization

    Write-up Format: Calculations, Partial Report: Results and Discussion Section

    Helpful readings: Engel and Reid, Thermodynamics, Statistical Thermodynamics and Kinetics (2e) ``Radical-Chain Reactions" and ``Radical-Chain Polymerization'' (sections 19.5 & 19.6, pg 508-512).

    1. Using the initial monomer concentration and the mass of your isolated polymer, calculate the amount of monomer remaining in solution at each time.
    2. Plot [M], ln [M] and 1/[M] vs. time to determine if the reaction is zero, first, or second order in monomer concentration. These plots should be worked into the text of your discussion section, not presented separately.
    3. Include a discussion of the order determination in your discussion section. Consider whether your results are conclusive.
    4. Important to include: Is your experimental rate law consistent with the theoretical mechanism?
    5. Consider the influence of the initiator on the reaction: Assume an average molecular weight of 15,000 g/mol and assume that one initiator molecule initiates two polymer chains. Calculate the amount of initiator left at the end of your experiment. Does the [Init] concentration change significantly during the reaction? How would you expect this to affect the rate of the reaction? How would this change the analysis of the data? Discuss these issues in your discussion section as well.

  • Monomer-Dimer Equilibrium

    Write-up Format: Calculations, Error Analysis, Partial Report: Abstract and Introduction Section

    Helpful readings: Barrante, Applied Mathematics for Physical Chemistry (3e) ``Mathematical Methods in the Laboratory'' (Chapter 12)

    1. These data will be worked up in class, along with appropriate error analysis.
    2. Details on Abstract and Introduction sections will be given in class.

  • Heat Capacity Ratios

    Write-up Format: Calculations, Abstract, discussion of results

    Helpful readings: Engel and Reid, Thermodynamics, Statistical Thermodynamics and Kinetics (2e) ``Equipartition Theorem'' (page 349), "Vibrations" (subsection 15.2.3 of Energy and Molecular Energetic Degrees of Freedom, page 365-366) and ``Heat capacities'' (section 15.3, pg 368-370).

    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.


  • Liquid-Vapor Equilibrium

    Write-up format: This lab requires a full formal lab report.

    Helpful readings: Engel and Reid, Thermodynamics, Statistical Thermodynamics and Kinetics (2e) ``Temperature-Composition Diagrams'' (pages 206-208) and "Raoult's Law" (pages 200-206, 214-217).

    1. Prepare a liquid-vapor temperature-composition phase diagram for the cyclohexane-ethylacetate system. You may prepare your plot in terms of either mole frations or weight percents, but you must be consistent throughout your report.
    2. Determine the azeotropic composition. Compare with literature values. (Be careful how these values are reported in the literature - they may be reported in terms of percentages by mole or by weight - make sure you convert values into the same units.)
    3. Discuss the following: What kind of deviation from Raoult's law is this? What are the possible reasons for the deviation on a molecular level? Comment on any points you had to throw out.
    4. Estimate the uncertainty in your azeotrope.
    5. Be sure to include the calibration data and curve and to report the pressure.
    6. Calculate an ideal solution curve for this system as described in calculations section of the lab handout. Comment on this compared to your$



  • Particle in a Box and Ring - Electronic Spectroscopy

    Write-up Format: Required activities are described in handout.

    Helpful readings: Engel, Quantum Mechanics and Spectroscopy (2e) ``The Particle in a One-Dimentional Box'' (section 4.2, pages 49-53), "Two and Three Dimensional Boxes'' (section 4.3, pages 53-54), "The Huckel Model" (section 13.7, pages 283-288) and sections 14.5-14.6 (pages 302-305) from the ``Electronic Spectroscopy'' Chapter.

    1. Calculations are described in the handout.



  • Kinetic Salt Effect

    Write-up format: This lab requires a full formal lab report.

    Helpful readings: Engel and Reid, Thermodynamics, Statistical Thermodynamics and Kinetics (2e) ``ionic strength'' (see equation/discussion on page 242) ``Reaction Rates and Reaction Mechanisms (pages 446-455)'' and ``Second Order Reactions'' (pages 458-459).

    The write-up should contain the following:

    • Tables of experimental data, including calculated values for [ C6H8O6] and [K3Fe(CN)6] at each time.
    • Plots of ln ( [ C6H8O6] / [K3Fe(CN)6] as a function of time for each trial
    • Calculated values for the rate constant k for each trial
    • Plot of the log k as a function of I1/2/(I+I1/2). (see eqtn 28-12)
    • A value for ko with uncertainties
    • A value for ZAZB
    • Discuss whether your data support or refute the proposed mechanism. (i.e. how are your data consistent with the mechanism? inconsistent?) This is imperative for a good discussion section.
    • Discuss how the ionic strength affects the rate of the reaction in terms of the kinetic salt effect.
    • All of the above should be written in a well organized prose format, just like the results and discussion section of a full lab report. This includes interspersing data tables and plot with text containing complete sentences to guide the reader. Do not simply provide a list of tables/plots and answers to questions. Final results should be reported and then put in context in this discussion section by addressing the specific issues mentioned the previous two items.
    • Sample calculation/description of how you obtained all values should be included. They may be attached and handwritten.


  • Langmuir Adsorption

    Write-up Format: This lab requires a full formal lab report.

    Helpful readings: Engel and Reid, Thermodynamics, Statistical Thermodynamics and Kinetics (2e) ``Homogeneous and Heterogeneous Catalysis'' (sections 19.4.5, pages 504-508).

    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



  • Vibrational Spectroscopy

    Write-up Format: Will be described in handout.

    Helpful Readings: TBA

    1. This experiment may be modified due to new equipment! Stay tuned!