CHE 443G

THE UNIVERSITY OF KENTUCKY

DEPARTMENT OF CHEMISTRY

CHE 443G Physical Chemistry Laboratory


Course Description: A continuation of CHE 442G. Laboratory studies in physical chemistry to accompany CHE 442G with emphasis upon the proper treatment of data. Laboratory, six hours; recitation, one hour. Prereq or concur: CHE 442G.

Course Information

Textbook:

"Experiments in Physical Chemistry", Shoemaker, Garland, and Nibler, 5th edition, 1989, McGraw-Hill.

Instructors' Evaluation

The instructors' evaluation component of the grade will be determined jointly by all the instructors in the course. A basic consideration will be whether or not the average grade of the written components is an adequate measure of performance in this laboratory course. Factors that will be considered are safety, laboratory technique and performance, preparation for each lab, understanding of the experiments, contribution to the partnership, housekeeping, attendance and punctuality.

Laboratory Experiments

Each Student must do the introductory experiments on density of solutions. Seven other experiments must be completed from the list of available experiments. A brief report on each experiment will be due two weeks after the experimental work is completed. Brief reports are described elesewhere in this handout. In addition, a journal report on one experiment is required; the journal report is described elesewhere in this handout. All reports (journal and brief) must be typed using a word processor. Computers with the appropriate software are available in CP-148.

Make-up Examination

Make-up examination will only be given for an excused absence.

Academic Dishonesty

You are hereby notified that the department of Chemistry considers cheating a very serious offense and that we will do everything possible to prevent cheating in this course. The minimum penalty for cheating in any form is the assignment of a grade of E for the course. Sanctions imposed may include, and have included, suspension, dismissal, and expulsion from the University.

"Dry labbing" is regarded as cheating.


Physical Chemistry Experiments

In addition to the density of solutions experiment that everyone does, you must complete seven experiments. At least one experiment must be completed from each of the categories: Calorimetry, Kinetics, Electrochemistry, Structure, Phase Diagram, and Equilibrium. The UK numbers in the list refer to instructions on handouts; the SGN numbers refer to experiment numbers in Shoemaker, Garland, and Nibler, EXPERIMENTS IN PHYSICAL CHEMISTRY, Fifth Edition.

  Calorimetry
  RS/PC  UK-1    Solution Calorimetry
  BH/TK  SGN-6   Bomb Calorimetry

  Kinetics
  RS/PC  UK-3    Ionic Strength and Rate of Reaction
  RS/XZ  UK-4    Bromination of Acetone
  RS/XZ  UK-10   Inversion of Sucrose

  Electrochemistry
  BH/XZ  UK-5    Transference Numbers by Moving Boundary
                 Method
  RS/PC  UK-6    Thermodynamics of a Galvanic Cell
  ML/TK  SGN-17  Conductance of Weak Electrolytes

  Structure
  ML/TK  UK-7    Magnetic Susceptibility (see SGN-33)
  ML/PC  SGN-38  Infrared Spectroscopy (handout)
  ML/TK  SGN-40  Spectrum of the Hydrogen Atom (handout)

  Phase Diagram
  BH/PC  SGN-14  Liquid-Vapor Phase Equilibrium in Binary Systems
                 (handout)
  BH/XZ  SGN-15  Phase Diagram of a Binary Solid-Liquid System

  Equilibrium
  BH/TK  UK-9    Determination of the Keq for the Decomposition of
                 Ammonium Carbamate
  ML/XZ  SGN-13  Vapor Pressure of a Pure Liquid by the Isoteniscope
                   Method (handout)

General Comments

Lab Fee

When you register for CHE 441 or CHE 443, a $40.00 fee will be added to your registration fees. This fee consists of a $20.00 non-refundable charg e and a $20.00 refundable breakage deposit.

Experiments

Usually two or more students will work together on an experiment. The first experiment for everyone will involve measuring the densities of solution s; this will serve as an introduction to the laboratory, an exercise in the treatment of data, and practice in report writing. After this first experiment, you must complete seven more experiments, with at least one chosen from each of the six categories: Calorimetry, Kinetics, Electrochemistry, Structure, Phase Diagrams, and Equilibrium.

Working Independently

Although you will usually work with a partner in doing the experiments, everything else MUST BE DONE INDEPENDENTLY. The calculations and other aspects of the reports must not resemble those of your partner or of anyone else who is now taking this course or has ever taken this course.

Equipment

The equipment for each experiment is located in a specific desk in the laboratory; that desk is assigned each period to the student scheduled for the experiment.

Much of the equipment in the physical chemistry laboratory is costly, especially if it is calibrated, or large, or of intricate construction. Glass equipment is breakable--if mishandled--even though it is well constructed. The instruments are particularly susceptible to abuse. They should not be used until you have learned their operation from the instructor. It is advantageous to exercise both thought and care in handling equipment; you are financially responsible for your breakages.

At the end of the laboratory work each period, the equipment is to be dismantled (if necessary), cleaned, and arranged neatly in the drawer and locker. Solutions which must be kept until the next lab period should be labeled and stored in the lockers designated, and a signed note should be left in the desk itemizing the borrowed equipment. When you have cleaned all the equipment, the instructor will check you out of the laboratory and initial your notebook. (Daily checkout is necessary because of alternating laboratory sections using the same equipment.)

Preparation

You should study the experiment and plan the work before coming to the laboratory. It is helpful to read the next experiment before the second day of the current one and to take five or ten minutes of lab time to observe the next experiment and consult with those who are doing it.

Housekeeping

Housekeeping in the physical chemistry laboratory will be emphasized. A clean laboratory is not only an indication of the "lab sense" of those working in it, but also a more pleasant, more reliable, and safer place to work. The following will be observed:
  1. Triple-beam balances may be used at your desk and returned (clean) to the balance room after use.

  2. Spillages must be cleaned up immediately. This applies not only to the desk and floor in the vicinity of one's working area, but also to the analytical balance areas, the acid-base shelf, the hoods, and areas around special equipment (such as refractometer, spectrophotometers, etc.)

  3. Spilled solids, waste papers, broken glass, etc., are to be disposed of in the waste jars under each sink. Water- insoluble liquids and solids mustbe transferred to special waste containers located in the hoods. Only non-toxic aqueous solutions with pH 2-12 may be put in the drain.

  4. Drawers should be closed and locker doors shut except when equipment is transferred.

  5. Auxiliary equipment, such as ring stands, should be returned to the proper storage areas at the end of each period.

  6. Personal lockers should be left closed and should not be used for hanging out towels to dry.

  7. A sponge or towel should be used to clean your working area at the end of each laboratory period.

SAFETY

In the physical chemistry laboratory safety will be observed at all times.

  1. Read the Safety Appendix E in Shoemaker, Garland, and Nibler.

  2. Safety glasses must be worn at all times while you work in the laboratory

  3. Know the locations of the nearest fire extinguishers and safety shower.

  4. Use gas burners with discretion.

  5. Treat chemicals with respect.

  6. Recognize the health hazards associated with each specific type of chemical, such as concentrated sulfuric acid, phenol, mercury, volatile organic materials, etc., etc., etc. Handle each with care and dispose of it properly.

  7. Remember that compressed gas cylinders are extremely dangerous if mishandled.

Personal Lockers

These are small cabinet drawers for the storage of safety glasses, towels and other small items. They are not lockable; valuables should not be kept in them.

Barometer

A barometer is located on the wall of the balance room in the laboratory. A description of its proper use and a table of temperature corrections are in your lab textbook (see page 720 and appendix D).

Balances

Balances are sensitive pieces of equipment and should be used with care the following rules must be followed.
  1. Learn the proper use of all balances you use. Turn knobs and levers carefully.

  2. Do not transfer chemicals within the balance cases.

  3. Never place chemicals in direct contact with the balance pans; use weighing bottles.

  4. Clean up spills in the balance or in the balance area immediately.

  5. Sign the log sheet every time you use a balance.

Grading

The grading of laboratory reports and notebooks (yellow sheets) is a subjective procedure under any circumstances. Bearing this in mind, try to make the most favorable impression with your work, attitude, and presentations. Particular attention in the grading is given to the completeness, format, and readability of the material. Calculations are expected to be correct; the results should have appropriate units and should be expressed to the correct numbers of significant figures. The narrative is expected to reveal an understanding of the basic theory and of the significance of the experimental details. The summary and discussion are evaluated on the basis of scope and cogency. The accuracy of the results is an important, but secondary consideration.

Independent Preparation of Physical Chemistry Laboratory Reports

Even though you have a partner in doing Physical Chemistry experiments, the laboratory reports you turn in must be prepared independently. The organization, the calculations, the discussion, the error analysis, and the literature listing must not be copied from your partner, from another student in the course, from a report from a previous year, or from any other source. Except for the data you and your partner collected together, everything in the report must be your own work. Paraphrasing or slightly varying someone else's wording is considered plagiarism.

Discussion of the experiment and the method of calculation with your partner is fine, and even encouraged. But the report must demonstrate your understanding of the experiment.

Evidence of submission of lab reports that are not original will be treated as a violation of the Student Code (Part II, Section 3.1, August 16, 1990 edition). The relevant passages from the Student Code are:


PHYSICAL CHEMISTRY LABORATORY NOTEBOOKS AND REPORTS

General Comments

  1. The notebook should be bound, with numbered pages and provision for removable carbon copies. National No. 43- 649 is recommended.

  2. The first three pages of your laboratory notebook should be reserved for a table of contents, which is to be kept up to date.

  3. No pages should be skipped in your laboratory notebook to allow space for the completion of an incomplete experiment. The situation can be handled adequately through the table of contents and by suitable referencing in your notebook.

  4. All entries are to be made in ink (preferably blue or black ball point) and during the regular laboratory period while the experimental work is in progress, except for the instances mentioned below.

  5. The title of the experiment, "continued" if applicable, your name, and the date should be entered on the top (right-hand corner) of each page.

  6. Data and descriptive material are to be entered directly into your notebook.
  7. There are to be no intermediate scratch sheets.

  8. Mistakes are to be clearly crossed out but left in a legible manner (to avoid giving the impression of trying to conceal something). The reason for the correction should be noted.

  9. Your notebook should be neat, orderly and complete. Another chemist, chemical engineer, or chemical patent lawyer should be able to take your notebook either now or months later and be able to read it and to understand what you did and the results you obtained.

Daily Procedure

At the start of each laboratory period, after checking your equipment carefully, entering the title of the experiment on your data page, etc., request the instructor to sign or initial your book before you proceed with your laboratory work. Non-initialed work will be considered unacceptable.

During each laboratory period, enter data and comments in your book according to the guidelines given below.

At the end of the laboratory period, after you have cleaned and dried the equipment and arranged it back in the desk, request the instructor to check you out of the laboratory. If everything is in order, the instructor will initial and date your book. If it is not in order, you will be instructed to remedy the deficiencies. Turn in yellow sheets with the day's data before you leave.

Duplicate Sheets

All duplicate (yellow) sheets associated with the experimental work done during a laboratory period are to be turned in at the end of that period. (Tables, etc., should be planned accordingly.) All remaining yellow sheets for a given experiment (calculations, conclusions, etc.) are to be turned in at the beginning of the next laboratory period (following completion of the experimental work) for which the laboratory is open for members of the course.

There will be a penalty for lateness.

Guidelines for Notebook_Entries

Most lab time should be devoted to experimental work rather than writing. However, it is useless to do the work unless it is properly recorded for later use and reflection. Not only should essential measurements and precise procedures be recorded, but also all conceivably pertinent observations. A slight change in procedure, a seemingly insignificant observation, etc. is often a crucial matter in the final analysis.

A number by itself is meaningless; therefore, the units, corrections, and information which make its interpretation meaningful should be carefully noted. There should be sufficient information about conditions, reagents, and equipment that the experiment can be repeated to give essentially the same results.

Preliminary

Before coming to the laboratory, write a short paragraph stating the property or properties which are to be measured, the results which are to be calculated, and how these are to be done. For example one might measure the distance a cannon ball falls during each of five different periods. The acceleration of gravity might then be calculated from a plot of distance versus time squared.

Experimental

All numerical data must, of course, go into the notebook as soon as they are determined, with no intervening scraps of paper!!!! The following information should always be included.
  1. The specific system you are studying (although you may not know its identity until after the experiment).

  2. Procedure: This should be written as each portion of the experiment is performed. The procedure should be as short as possible and still contain enough of the detail that another chemist could repeat your work.

  3. Data: All the numbers must be written and their units indicated--even an initial burette reading of 0.00 mL. There should be some explanation or heading for every set of numbers. The uncertainty for each type of measurement should be indicated. It is suggested that you do short calculations, such as subtraction of weighings, additions, etc., right on the data page before you turn it in and leave lab.

  4. Comments: Put down anything that might be pertinent or helpful. It is better to write down things which you may not need than to inadvertently leave out something significant. The comments may be in "note" form as long as they are complete enough to be intelligible to others.

    Comments, Data and Procedure belong together. They should not be separated under three different headings.

  5. Equipment and Chemicals: It is not necessary to describe standard or "everyday" glassware or hardware which might be used in any experiment. Larger or special equipment and instruments should be described:

  6. Specially constructed glassware or other equipment (such as the Choppin-Cottrel Boiling Point Apparatus) should be described either by a labeled sketch or a complete reference to the detailed description in the literature. Chemicals should be described by the name and formula. Manufacturer, grade, and lot number should be given where possible.

Evaluation

Before attempting an evaluation of your experiment, you should be familiar with generally used methods of treating experimental data.1 Under the heading you should describe your results and your method for obtaining these results. This should include a discussion of the significance and reliability of the results with sufficient discussion to justify the use of your procedures. Entries in your notebook should follow the general pattern described below.

  1. Sample calculations: illustrate all computations by writing the appropriate formula or equation, substituting a sample set of data (with units) and listing the answer, e.g.

    P = 1/(nRT,V)

    P = 1/((3.00 moles)(0.0821 L atm/mol K)(373 K)(0.211 L)) = 435 atm

    In general, do not carry out calculations in the notebook; use separate paper and tabulate the results in the notebook. Each calculation should be carefully double checked.

  2. Results: Collect your results and organize them so that they can be easily assimilated and compared. Tables and graphs should be titled and completely labeled. You may want to plot several pieces of similar information on the same graph for easy comparison. Shoemaker, Garland, and Nibler's recommendations for graphing should be followed. Use good quality graph paper, not notebook pages, for all graphs. Computer plots showing all experimental points are acceptable.

  3. Programs: If you develop a computer program for the analysis of your data, the print out from the program must be neatly stapled into your notebook. Also include a listing of the program, which should be neatly stapled into your notebook. Make sure to include a hand written sample calculation as outlined in 1. above. Acknowledge any help in programming from outside sources, including help from your fellow students.

  4. Literature Comparison: Whenever possible your experimental result should be compared with accepted or typical literature values. These comparisons should include notations of significantly different experimental conditions or procedures. Both absolute and relative differences should be included after the data have been adjusted to the same temperature, pressure, etc.

  5. Commentary: Briefly and quantitatively assess the accuracy and precision of your work in light of the uncertainty in the measurements which you have made. If there is a circumstance (duly noted as a comment in your notebook) which would explain good or bad results, describe it and give an estimate of its magnitude and effect.

If you have suggestions for improvements in the design or recommended experimental procedures, make them here. Be concise in this section as well as all other parts of your write-up.

_____________ D. P. Shoemaker, C. W. Garland, and J. W. Nibler, "Experiments in Physical Chemistry", 5th edition, McGraw- Hill Book Company, New York

Guidelines for Laboratory Report Evaluation

  1. Preliminary (5 pts.):

  2. Data and Procedure (10 pts.):

  3. Calculations (10 pts.):

  4. Discussion (10 pts.):

  5. Error Analysis (7 pts.):

  6. Literature (3 pts.) (You may not omit this section):

  7. Form and Neatness (5 pts.):

  8. Late Penalty (-2 pts. per day late)

  9. No-Show Penalty: (-5 pts.)

  10. Repeating a Report:

Journal Reports

The journal report is a formal report on one of the experiments you completed, written as though it were a manuscript being submitted for publication in a scientific journal. Good models for journal reports are full length papers in the Journa l of Physical Chemistry. Examine some of these in the library.

Your journal report should contain the following components.

Title:

Every word in the title should be chosen carefully to describe as succinctly as possible the contents of the report.

Abstract:

Within 250 words, state the objectives and scope of the work, describe the methods used, summarize the results, and present the main conclusions. The uncertainties of numerical results should be given. Someone should be able to understand from the abstract what the experiment was about and what your results were. The abstract must be complete in itself, and everything in it should make sense even if separated from the rest of the paper. Critical features of the abstract are that it should be brief and to the point.

Introduction:

Describe the nature and scope of the problem under study (for example, you determined the activity coefficients of a solute by measuring the freezing poin t depression of solutions in cyclohexane). Present briefly the theoretical background or important principles that underlie the experiment. State the important equations that will be used, but do not repeat standard textbook derivations. Number each important equation that you will be referring to later. Make clear all important assumptions involved in deriving the equations. Refer to pertinent literature.

Materials and Methods:

Give sufficient details of your experiment so that another competent scientist could repeat your work and reproduce your results. Identify chemicals by formal chemical name and grade. Identify large instruments by manufacturer's name and model number (e.g., Perkin Elmer Model 283 Infrared Spectrophotometer). Include a diagram of any special or unusual apparatus, but just refer to the textbook for diagrams of widely used instruments.

Results:

Where possible, arrange data in clear, well organized tables. Usually you should not include all the numbers written in your notebook; that is, include the weight of a sample, not the weights of a bottle with and without the sample; the pressure of a gas, not the heights of the two manometer arms. Tables, graphs, and figures should be numbered and referred to by number in the text.

Outline the calculations performed, but do not give sample calculations. Refer to important equations by number. Give uncertainties for all derived results. Rules for significant figures should be followed carefully. All quantities should be labeled with proper units.

The critical feature of the Results section (and indeed the whole report) is clarity. It must be very clear what the results are, how they were obtained, and what their uncertainties are.

Discussion:

Discuss, not just present again, your results. Compare your results with literature values. Identify sources of error or limitations in the experimental apparatus or equations used. Suggest improvements. Point out any theoretical or practical significance of your work.

Acknowledgments:

Recognize the assistance of coworkers, partners, or anyone else who contributed to the paper, either by data collecting, by discussion, or by advice.

Literature Cited:

List by number all papers or books referred to in the text. Give full references following the abbreviation scheme used in American Chemical Society journals, such as the Journal of Physical Chemistry.

English and Grammar:

The journal report should be free of grammatical, spelling, or punctuation errors. Read it carefully before you turn it in. Make sure that each phrase means what you intend to say, that sentences are complete sentences, that subjects and verbs agree, that tenses are not mixed. The writing generally should be in the past tense; state what was done, not what someone should do.

Figures and Diagrams:

All figures and diagrams should be drawn on separate sheets of paper in ink and appropriately labeled. Computer diagrams are desirable, but make sure that they have complete captions and labels. Graphed points should be connected by smooth curves, and the axes on graphs should be labeled.


SAFETY RELEASE

  1. The Chemistry Department makes every effort to run instructional laboratories safely.

  2. Students who have special medical conditions (e.g., severe allergies, pregnancy) should consult with their personal physicians before beginning laboratory work. The Chemistry Department will be happy to work with a student's personal physician in attempting to determine the level of risk to that particular student.

  3. The responsibility of the Chemistry Department for a student in a laboratory may be different if that student is not yet 18 years old. Please mark the appropriate line below:

  4. Removal of chemicals, glassware or any other items from any laboratory in the Department constitutes a potential safety hazard to individuals in the community who are not familiar with their safe handling. Any student alleged to have removed any item from the building will be reported to the police. Any student caught removing any item from the building will be prosecuted. The case of any student convicted of removing an item from the building will be automatically turned over to the Dean of Students and charged with a disciplinary offense. The Department may recommend that the Dean of Students seek the harshest of University sanctions, which include expulsion.

  5. Please read the following statement. If you accept the statement, please sign and date it in the spaces provided. No laboratory work may begin until this statement has been signed.

I certify that I have been instructed in laboratory safety procedures and agree to abide by them, that I have given correct information about my birth date, and that I have read the paragraph (2) above.


  Signed  _________________________________

                           Date     _________________________________

                           Class    _________________________________
                                                                         
Physical Chemistry Laboratory

SAFETY STATEMENT

        SIGNED_____________________________


        DATE _______________________________

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