Organic Chemistry Laboratory Procedures
Important Information
Robert J. Shine
January 21, 2004
Attendance
Each lab session will begin at exactly 2:00 PM. Attendance at all laboratory sessions is mandatory. You must sign the attendance sheet for each lab session. A missed laboratory experiment cannot be made up at another time and any missed laboratory session will result in a grade of zero (0) for that experiment. In computing your final grade, the lowest lab grade will be dropped. So, you are allowed to miss one lab (other than the final test) without any grade penalty.
Each graded laboratory session will be worth 100 points. Your in-lab work will count for about 40 of those points and your reporting will count for about 60 points. The final laboratory exam will be worth 200 points. In computing the final lab grade, the lowest score (other than the final lab test) will be dropped, all other points will be added and the total will be normalized to a 100 point scale. Letter grades are assigned as follows: A ( above 93.00), A- (90.00 to 93.00), B+ (87.50 to 89.99), B (84.00 to 87.49), B- (80.00 to 83.99), C+ (77.50 to 79.99), C (74.00 to 77.49), C- (70.00 to 73.99), D (65.00 to 69.99), F (below 65.00). In grading laboratory sessions, the following will be considered: meeting deadlines, submitting the necessary forms and reports on time and in good order, being on time for lab, and working in a safe and efficient manner.
Before leaving the laboratory, each student must submit a laboratory data sheet as described by the instructor. Lab reports can only be submitted for labs that have been attended and must be submitted at the beginning of the lab session following the lab that is being reported. Points will be deducted for lateness or for an incomplete lab report. No lab report for a given experiment will be accepted after graded reports for that lab have been returned to the class. Generally, graded lab reports will be returned in the next class meeting after the report is submitted. A score of zero is assigned for a report if the lab report is not submitted.
Students are required to purchase lab goggles that must be worn at all times when in the laboratory when experimental work is being done. Students who fail to wear eye protection may be asked to leave the lab.
Students should have a notebook that will be used in the lab for recording all raw data. A title should appear at the top of the page for each new experiment. Data obtained during an experiment should always be recorded into this notebook. Preprinted forms will be handed out for you to complete and turn in as required.
It is imperative that students be prepared to perform the scheduled experiments. An unprepared student is a hazard in a chemistry laboratory. In order to prepare for the experiment, students are expected to read the appropriate material in the lab textbook prior to reporting to the lab. Each student must prepare and submit a prelaboratory data form. This form must be submitted when you enter the laboratory. Students may be tested at the beginning of the lab period to ensure they are prepared to begin work.
Laboratory reports must be typed on 8.5 x 11 inch white paper. The report should have a professional appearance and it must demonstrate that much thought and care went into its preparation. Spelling and grammar count. All laboratory reports must be written in the following format that conforms to the guidelines set forth by the American Chemical Society:
Cover Page – Place the following information in the upper right hand corner
Title of the experiment
Name of Student submitting report
Date of Submission
The abstract consists of two to four sentences that concisely inform the reader of the nature of the experiment that was performed and a brief summary of your final results. Note that the abstract is read immediately after the title and hence should not repeat any information that already appears in the title. Though the abstract appears at the beginning of the lab report, it should be the last section of the report that is composed. The abstract should be about 30 to 80 words and should give a concise description of the experiment. It should not be too general or too specific.
The introduction consists of one or two short paragraphs that relate only the most essential elements of theory to the reader. Consult the lab manual and a chemistry textbook for this information. Include only enough theory so that the reader is made to understand the basic physical and chemical principles involved in this experiment. If applicable, any pertinent mathematical and chemical equations must be briefly given in this section. The introduction should conclude with a one- or two-sentence paragraph that explains the objective or goal of the experiment.
Students shall describe all relevant safety precautions that were observed during the course of the experiment. Information about the hazards that may be encountered is particularly important. If Material Safety Data Sheet information is included, you should give a summary of the pertinent data and not just a copy of the msds.
For our purposes, the experimental section will consist of a short paragraph that includes a sentence that refers the reader to the lab manual for the procedure. For example, the student may write: "The procedure for this experiment appears in the lab manual (1)." The number in brackets refers to the citation number. This number is used to refer the reader to the citation in the References section where the full reference (including name of author, title of book or paper, date of publication, and page number) will appear next to number 1. In addition to the reference citation, any deviations from the published procedure and any experimental hints or tips that may aid the reader in understanding and repeating the experiment should be included. For example, “In this experiment, the instructor requested that we use 0.05M HCl instead of 0.1M as specified in the module.”
This section consists of a written paragraph that refers the reader to tables, graphs, data sheets, and figures that contain your data. It is especially important to inform your reader how your raw data were used to calculate your final results. You must explain how you determined your final results and include sample calculations with an accompanying explanation is necessary. The use of a spreadsheet program (such as Microsoft Excel) for calculations, tabulation of results, and graphing is encouraged.
This section is used to indicate to the reader how the results relate to the theory and whether or not the objective was met. In addition, the final results should be compared to literature values, if available. Reasonable sources of error should be listed and discussed with respect to their contribution to the final results. The discussion provides a good indication of the student's comprehension of the material. A good discussion should show that the student was able to correctly interpret the data and to relate the results to the scientific principles being tested by the experiment. If the experiment was not successful, then the discussion is equally important in relating the reasons for the outcome. A good discussion can be written regardless of the success of the experiment.
This section should include a summation of the Results and Discussion. It should only be about 1 paragraph long and is intended to draw together all the pertinent information that has been determined from the experiment.
This section consists of a numbered listing of literature references that were used to perform the experiment and that were used to write the lab report. This includes a full reference to the lab module and any other publications or correct web page URLs that you may have used to obtain literature values and supplemental theory. Note that the reference numbers must correspond to the reference citations used in the text of the report.
Read the following items carefully as these suggestions are given to help you achieve good lab report grades. Failure to use this advice will result in a significant lowering of your future lab report grades.
1. The most misused word I am seeing in your reports is the word “vile”. The dictionary defines “vile” as: mean, worthless, unclean, repulsive, bad. The same dictionary defines the homonym “vial” as: a small vessel. In all reports where I have seen the word “vile” used I believe the word “vial” should have been used instead.
2. Some students are beginning to omit the Safety section in their lab reports. This section is very important and should address the specific safety concerns for the experiment written in that report. Safety sections that include MSDS summary information (with correct references) are graded more favorably than those sections that simply include a printout of the MSDS or do not include MSDS data at all. Failure to include a safety section will result in a lab grade of B or less.
3. Many lab reports need to include information about percent yield calculations. This section should be neatly done and very clear in its presentation. You must show how the calculations are done in an area that is separated from text. Do not put data details in text. Present data details in tabular form and be sure this data is near the text that describes it for clarity of presentation. Calculations should be close to where the final data is presented in your report. Briefly, a percent yield calculation is an application of a weight-weight problem in General Chemistry. You calculate the number of moles (or millimoles) of each reagent. Then, determine from the balanced equation the maximum number of moles of the desired product that could be obtained. Convert this number of moles of product to weight of product. Then, divide the weight of product that you obtained by the theoretical weight of product you calculated and multiply by 100 %. Percent yield calculations will be a major part of your report grade in those labs where percent yield data needs to be reported.
4. Be sure your report has a correct logical flow. For example, give the data before the conclusions that are made.
5. Be sure you use terms (especially scientific terms) correctly. Failure to use technical terms correctly will have a definite negative impact on your report grade. For example, do not report the boiling point of a solid, report its melting point.
6. Be sure to record the units associated with a measurement and be sure to use correct significant figures with your data.