CHEM 427L is a one semester, one-credit laboratory course that covers laboratory methods in advanced physical chemical. The course includes experiments in molecular spectroscopy, thermodynamics, surface chemistry and electrochemistry. Students are introduced to and are expected to use advanced data handling and error treatment methods. Personal computers are available for use in data analyses.
Arthur M. Halpern Experimental Physical Chemistry: A Laboratory Textbook, 2/ e, Engineering/Science/Mathematics , Copyright 1997, 610 pp. ISBN 0-13-654203-4
MWF 10-11, 3-4 R 1-2 or by appointment
Byrd Center 113 304-876-5430 email@example.com
web page: http://WEBPAGES.SHEPHERD.EDU/DDILELLA/
R 9:10 - 12:00
CHEM 427 and CHEM 428 are prerequisites or should be taken concurrently. Computer skills are not a prerequisite but students who do not know how to do basic computer spreadsheet operations should see the instructor as soon as possible to get special tutoring in these skills.
Students are expected to attend all laboratory sessions. Students must get their lab notebooks signed during each period. Makeup labs will not be administered without a valid written excuse. Labs that are missed with a valid excuse may be made up at a time determined by the instructor. Students may NEVER work in a lab without permission of the instructor or without supervision.
The experiments are designed with safety as a major consideration. If you always do exactly what the authors describe hazards are minimized. However, in many cases you will be working with unfamiliar apparatus and unexpected dangers may be present. Be sure that you understand the hazards associated with your equipment before you start an experiment. Do not be afraid to ask questions. SAFETY GOGGLES OR GLASSES MUST BE WORN AT ALL TIMES.
PREPARATION BEFORE THE LABORATORY
You will be able to work much more efficiently in the lab if you understand what it is you are trying to do. Read the text before you come to lab. To work most efficiently, you should know how you will prepare solutions before you come to lab so you will not waste valuable lab time. Many students spend so much time figuring out how to make solutions that they do not have enough time to collect good data. Be prepared. The time spent in preparation is time that you will not have to spend in the lab. A well-prepared student can often make much progress on his/her lab report during the laboratory time.
All data and observations should be entered in a bound lab notebook. Entries should be complete and neat. Every page should include the date and the name of the experiment. All data needed to reproduce the results should be included. Whenever possible the data should be entered in the form of a table. All notebook entries should be labeled and should have the correct units. Your notebook should be signed by the instructor at the end of each lab period.
The final grade in this course is based solely on the basis of the lab reports.
The final grade will be based on the following scale:
A 90 % to 100 %
B 80 % to 89+ %
C 70 % to 79+ %
D 60 % to 69+ %
Reports will be graded on a scale from 0 to 100. Each report will have equal weight. Your final grades will be based solely on the scores of your reports.
Reports are due one week after the completion of the experimental work. You will lose 2 points of your score for every day that the report is late.
Three labs will require formal reports. One of the first three reports should be a formal report. Short reports will be sufficient for the others. See below for details on what is expected for each type of report.
Points will be deducted for the following on all reports: missing tables, charts or other attachments, incorrect significant figures, incorrect units, miscalculations, answers not justified by experimental results
Additional points will be deducted for the following on formal reports, missing literature values, incomplete answers to discussion questions
1. Introduction, experimental and general style.
The first page should include your name, the title and number of the experiment, the name of your partner and the dates on which the experiment was performed and submitted.
The introduction should be a brief summary of the purpose and experimental approach used in the experiment. A detailed discussion of the theory is not expected and will receive no extra credit.
The experimental section should be brief. State the source of the procedure that you followed and give details only for deviations from the published procedure. If you followed exactly the procedure in the book that is all you need to indicate in your report.
2. Results. (graphs, tables, etc.)
All data and results from calculations should appear in a table. The experimental uncertainties of the data should be included with each data point. All data should include the proper units unless the quantity is unit-less.
All tables and graphs should have titles. The axis on plots should be labeled and the dimensions of the quantities plotted should be indicated.
Plots should be generated by computer and should be constructed so that they can be read to the maximum possible precision. This simply means that you should use the maximum possible range on the paper. You should include a least squares line when appropriate. Do not connect the "dots". All data points should include appropriate error bars.
A sample calculation showing every step used to treat the raw data should be presented. It is neither necessary nor desirable to show repeated examples of the same basic steps. Describe the purpose of each step and indicate clearly the source of every quantity that you use in the calculation. Appropriate UNITS should be used throughout the calculation.
3. Discussion of results.
This is a very important part of the report but a long discussion is neither important nor desirable. Content, not length, is important. A concise half page summary will usually be sufficient. No more that one full page is ever necessary. The instructor does not enjoy reading irrelevant rambling prose any more than you enjoy writing it. The discussion should not include anything that is not relevant to the problem at hand.
The following topics should be discussed if possible.
a. State the major results (WITH UNCERTAINTIES) at the beginning of the discussion. Each experiment is designed for the determination of one or more physical quantities. Indicate that you understand the purpose for doing the experiment by making a clear statement of the results.
b. Discuss your results in terms of the appropriate theory. Did the data agree with theoretical predictions? Are there any significant approximations that should be considered? How would you expect the approximations to affect the final results?
c. Compare your results with literature values. If a literature value cannot be found you should be able to make some comment about the results based on your general knowledge of chemistry.
d. Answer all questions presented in the text. Those parts listed as optional in the text are NOT optional for you unless you are told so.
e. Suggest improvements that you would incorporate if you were to do the experiment again. For example, do you have any ideas on how the apparatus could be redesigned so that it would give more accurate results. Can you think of a better way to make the measurements?
f. List all references.
It is VERY IMPORTANT that you support all statements that you make. A statement such as , "The major source of error in this experiment was in making solutions", isnít very useful without specific supporting evidence.
4. Error analysis.
You will make a quantitative estimate of the quality of your results. For purposes of doing the error calculation you will assume that the relevant theoretical equations are accurate even if you know that they are only approximate. You will then discuss the consequences of any shortcomings of the theory and how they would affect the results. Do not just state that the results are expected to be wrong. Indicate whether the final result will be higher or lower than expected.
For every measurement that you make you should include an experimental uncertainty. The best time to determine the uncertainties is while you are doing the experiment. For example, if you measure a 10 mL volume that you believe to be accurate to 0.01 mL you record the measurement as 10.00 Ī 0.01 mL. Tolerances for volumetric glassware are tabulated in the textbook. In the case where there is no accepted uncertainty value it will up to you to make a reasonable estimate. The estimate will be based on the reproducibility of the data if more than one reading was made. In cases where only one reading is made you must make an educated guess that should, of course, include a justification.
Short reports will include all charts, tables, sample calculations and literature references. There should also be a brief summary of the results. Short reports will not include error analyses or long discussions.