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.
"Experiments in Physical Chemistry", Shoemaker, Garland, and Nibler, 5th edition, 1989, McGraw-Hill.
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.
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 will only be given for an excused absence.
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.
RS/PC UK-1 Solution Calorimetry
BH/TK SGN-6 Bomb Calorimetry
RS/PC UK-3 Ionic Strength and Rate of Reaction
RS/XZ UK-4 Bromination of Acetone
RS/XZ UK-10 Inversion of Sucrose
BH/XZ UK-5 Transference Numbers by Moving Boundary
RS/PC UK-6 Thermodynamics of a Galvanic Cell
ML/TK SGN-17 Conductance of Weak Electrolytes
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)
BH/PC SGN-14 Liquid-Vapor Phase Equilibrium in Binary Systems
BH/XZ SGN-15 Phase Diagram of a Binary Solid-Liquid System
BH/TK UK-9 Determination of the Keq for the Decomposition of
ML/XZ SGN-13 Vapor Pressure of a Pure Liquid by the Isoteniscope
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.
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.
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.
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.)
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 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:
- Triple-beam balances may be used at your desk and returned (clean) to the balance room after use.
- 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.)
- 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.
- Drawers should be closed and locker doors shut except when equipment is transferred.
- Auxiliary equipment, such as ring stands, should be returned to the proper storage areas at the end of each period.
- Personal lockers should be left closed and should not be used for hanging out towels to dry.
- A sponge or towel should be used to clean your working area at the end of each laboratory period.
In the physical chemistry laboratory safety will be observed at all times.
- Read the Safety Appendix E in Shoemaker, Garland, and Nibler.
- Safety glasses must be worn at all times while you work in the laboratory
- Know the locations of the nearest fire extinguishers and safety shower.
- Use gas burners with discretion.
- Do not use burners near volatile, flammable solvents.
- When burner is not being used, turn off the gas at the valve on the gas lines as well as at the burner.
- Treat chemicals with respect.
- Do not open flammable chemicals near a flame or spark source.
- Use propipettes or bulbs when pipetting acids, bases, or volatile or dangerous chemicals.
- 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.
- Remember that compressed gas cylinders are extremely dangerous if mishandled.
- Make sure that large cylinders are secured with a chain before they are used.
- Use care in carrying and handling small cylinders.
- Consult an instructor about opening the valves if you are in doubt or are unfamiliar with the valve.
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.
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 are sensitive pieces of equipment and should be used with care the following rules must be followed.
- Learn the proper use of all balances you use. Turn knobs and levers carefully.
- Do not transfer chemicals within the balance cases.
- Never place chemicals in direct contact with the balance pans; use weighing bottles.
- Clean up spills in the balance or in the balance area immediately.
- Sign the log sheet every time you use a balance.
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:
All academic work, written or otherwise, submitted by students to their instructors or other academic supervisors, is expected to be the result of their own thought, research, or self-expression. In cases where students feel unsure about a question of plagiarism involving their work, they are obliged to consult their instructors on the matter before submission."
"When students submit work purporting to be their own, but which in any way borrows ideas, organization, wording or anything else from another source without appropriate acknowledgment of the fact, the students are guilty of plagiarism."
"Plagiarism includes reproducing someone else's work, whether it be published article, chapter of a book, a paper from a friend or some file or whatever. Plagiarism also includes the practice of employing or allowing another person to alter or revise the work which a student submits as his/her own, whoever that other person may be. Students may discuss assignments among themselves or with an instructor or tutor, but when the actual work is done, it must be done by the student, and the student alone."
PHYSICAL CHEMISTRY LABORATORY NOTEBOOKS AND REPORTS
- The notebook should be bound, with numbered pages and provision for removable carbon copies. National No. 43- 649 is recommended.
- The first three pages of your laboratory notebook should be reserved for a table of contents, which is to be kept up to date.
- 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.
- 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.
- 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.
- Data and descriptive material are to be entered directly into your notebook.
- There are to be no intermediate scratch sheets.
- 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.
- 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.
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.
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.
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.
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.
- The specific system you are studying (although you may not know its identity until after the experiment).
- 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.
- 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.
- 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.
- 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:
- Name of item (or description) and size if applicable
- Manufacturer and model number or catalog number
- Serial number
- 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.
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.
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.
- 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.
- 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.
- 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.
- 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.
- 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.
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
- Preliminary (5 pts.):
- Must be done before TA signs you in (by 1:15 p.m.) or lose 5 pts.
- Include:What you are going to measure (the property and the chemical species).
- How you are going to measure it (equipment and method to be used).
- What you are going to determine (calculate) from the data.
- Data and Procedure (10 pts.):
- Neat data tables, showing units and uncertainty of measurement.
- Procedure written as you do the experiments, including comments and observations.
- Chemicals should be described by name, formula, manufacturer, grade, and lot number.
- Sketch of any "unusual apparatus".
- Instruments should be described by name, manufacturer, model number, and serial number.
- Calculations (10 pts.):
Show one detailed example of each type of calculation (showing units), then tabulate the results.
- Graphs: Good quality graph paper (lab notebook paper is not adequate).
Must use linear least squares to obtain slope, intercept, and their uncertainties.
Computer plots are acceptable if data points and axes are marked and labeled.
- Discussion (10 pts.):
Clearly state your conclusions about your final results and explain their significance.
Explain why or why not your answers or conclusions are reasonable, comparing them to literature values and/or theoretical predictions.
Include enough theory/background to show that you understand what you did in your experiment. You may comment on the theoretical models used for the experiment, especially their limitations.
- Error Analysis (7 pts.):
- Propagation of error.
- Show original equation and each logical step.
- Show % deviation from literature value.
- Literature (3 pts.) (You may not omit this section):
- Cite all references, including lab handouts, textbook, CRC, journal articles, etc.
- You need a minimum of three references for each report.
- Form and Neatness (5 pts.):
- Data and results should be tabulated.enough to achieve this goal.)
- Preliminary and data sheets should be signed in and out and turned in daily.
- Late Penalty (-2 pts. per day late)
- Reports are due 2 weeks from the day of completion of the experiment
- Late points are not assessed for weekends and official UK holidays.
- Reasonable requests for excusing the late points need to be discussed with the Professor. He will sign the report with a note for the grader if your excuse is accepted.
- No-Show Penalty: (-5 pts.)
- Laboratory space and the number of experiment stations are very limited. Subsequently, accurate scheduling of experiments is very critical in this class. If you sign-up for an experiment and then fail to show-up, five points will be subtracted from your grade.
- Repeating a Report:
- You may rewrite any one of the early reports you have had graded and
replace the first grade with the new one. A report submitted under this option
must be labeled REGRADE, and it must be turned in by March 3, 1995.
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.
Every word in the title should be chosen carefully to describe as succinctly as possible the contents of the report.
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.
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.
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.
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.
Recognize the assistance of coworkers, partners, or anyone else who contributed to the paper, either by data collecting, by discussion, or by advice.
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.
- The Chemistry Department makes every effort to run instructional laboratories safely.
- 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.
- 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:
- I have already passed my eighteenth birthday.
- (If not already 18 years old). My birth date is: _________________
- 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.
- 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.
Physical Chemistry Laboratory
- I am aware of the location of the fire extinguishers, fire blankets, emergency showers and eyewash devices in the physical chemistry laboratories at the University of Kentucky and I have been given instruction in the use of these devices.
- I have read and understand all portions of Appendix E entitled SAFETY in the textbook "Experiments in Physical Chemistry" by Shoemaker, Garland, and Nibler.
- I understand that I must wear safety glasses at all times in the laboratory.
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This page was last updated Nov. 01, 2004.