general chem lab report writing sample PDF

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the guidance for writing a lab report at first, with the required section but without a proper and general conclusion....

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Writing Laboratory Reports LAB REPORTS The preparation of a laboratory report is an exercise in logical and scientific writing which requires a thorough evaluation and interpretation of experimental data. A laboratory report is not merely a set of data, mathematically massaged to give the desired result. It should contain connecting prose and giving it continuity and meaning. The prose must meet reasonable standards of style, organization, grammar, and spelling. The discussion part of the report may require some critical thinking. An excellent laboratory result has a much-reduced value if poorly described in writing. The student laboratory reports should be typeset on 8.5×11 inch paper. Be sure to include the experimenter’s name, lab partner’s name, and labTA’s name. Copies of the laboratory notebook pages are not acceptable as a substitute for the report. Emailing lab reports to the laboratory instructor will not be accepted. Laboratory reports usually comprise several sections, including but are not limited to an introduction, experimental procedure, data and analysis, and discussion. Each lab section has a fixed scope essentially. However, depending on the experiment, the length and content may vary. It should also include references if any.

Introduction This section may start with the nature and purpose of the experiment and the techniques used. Do not copy the introduction in the laboratory manual.

Experimental Procedure This section is usually used to describe your experiment but should be brief. Generally, you may report only deviations from the standard procedure. Otherwise, do not copy anything from the lab manual.

Data Analysis This section should contain the essential and final data from your analysis. Whenever possible, summarize and show data tables and graphs. Students must perform all data calculations with proper significant figures. When calculating interim results, it is always good to carry an extra numerical figure and round it off at the very end. This practice will reduce the chance of rounding errors that may accumulate in consecutive steps and degrade the accuracy of your experimental result. Students should include sample calculations, one of each kind, in the data analysis, which will help the laboratory instructor track down any systematic errors in data reduction.

Discussion A discussion section in the lab report is always required. The discussion section will allow the students to examine the validity and discuss the meaning of the

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experimental results, e.g., Does it make sense? Is it close to accepted value or expectation? What is the major conclusion from the experiment? For some experiments, there will be additional questions assigned at the end of the lab write-ups.

References In writing a chemistry laboratory report, following the American Chemical Society (ACS) style guide (ISBN-10: 0841239991). Here are a few examples. Journal Article Dragisich, V.; Keller, V.; Zhao, M. An Intensive Training Program for Effective Teaching Assistants in Chemistry. J. Chem. Educ. 2016, 93, 7, 1204-1210. https://doi.org/10.1021/acs.jchemed.5b00577. Website The University of Chicago, Department of Chemistry Home Page. https://chemistry.uchicago.edu/. Books Coghill, A. M. (Editor); Garson, L. R. (Editor). The ACS Style Guide: Effective Communication of Scientific Information; American Chemical Society Publication, 2006

ALTERNATIVE OPTION: LAB REPORT FORMS Many times, a full lab report is not necessary for some specific lab assignments. See the next section for the lab report form. In such cases, the lab instructor would make any specific requirements explicit to students for the lab assignments. Students must finish their lab report form independently, without collaborating with classmates or anyone else.

SAMPLE LAB REPORT In the next section, we list a sample lab report to outline the expected laboratory reports.

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Sample Lab Report Outline AnExample: 

TheOxygenContentofAir Introduction In this experiment, we measured the percent composition of oxygen in the air. The measurements were made by inverting a graduated cylinder containing air and acid-soaked steel wool into a beaker containing water. The iron of the steel wool reacted with oxygen to generate rust (iron oxide). The acid served to speed up the reaction between the iron and oxygen. As the steel wool reacted with the oxygen trapped in the graduated cylinder, the volume of gas in the cylinder decreased, causing the water level in the inverted cylinder to rise. The decrease of the gas volume in the cylinder corresponds to the initial volume of oxygen inside the cylinder. We calculated the percent oxygen in the air from the change in the water levels and the initial volume of air trapped in the cylinder.

Procedure  The procedure was the same as in the lab manual, except three trials were performed rather than two.

DataAnalysis  Data: Height of cylinder = 125.5 mm Radius of cylinder r = 10.0 mm Trial #1

Trial #2

Trial #3

Initial height of water h1 (mm)

8.0

8.0

9.0

Final height of water h2 (mm)

14.0

25.0

29.0

Mass of steel wool m (g)

0.75

0.71

0.73

95.4

90.3

92.8



3

Volume of steel wool (mm ) 3

Volume of air (mm ) 3

3.69 x 104

3.69 x 10 4

3.69 x 104

3

3

6.28 x 103

Volume of oxygen (mm )

1.88 x 10

Oxygen percentage of air

5.10%

5.34 x 10 14.40%

17.00%

The average percentage of oxygen in the air was determined to be 15.7%. Note: We removed the data of trial #1 from this calculation. See the discussion section.

Samplecalculations: Here, students should show calculations for at least one trial. For example, using data from Trial #2, we have The volume of air = r2h =  10.0 mm)2(125.5 mm – 8.0 mm) = 3.69 x 104 mm3 …, so on so forth for each calculation, ...,

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Discussion We determined the oxygen composition of air to be 15.7% by volume. This value is much lower than the accepted value of 20.6% at sea level, yielding an error of 23.8% from the accepted value. We found that the first trial did not work correctly; the value of 4.80% O2 from trial #1 was outside the standard deviation of the average of the three results, which indicated that it was probably not a good set of data points. So, we did not include the data from the first trial. The first trial used an overly packed steel wool, tightly set in the bottom of the graduated cylinder. Our TA indicated that this might cause a problem. Because the oxygen must react with the steel wool to be “detected,” the more tightly the steel wool is packed, the less chance the oxygen has to diffuse to the surface of the steel wool and react. Our results indicate that the procedure is not a very accurate predictor of oxygen content. Empirical evidence suggests that the oxygen content in the lab room was typical (everyone was breathing normally), yet we determined the percentage of oxygen to be 23.8%, below what it should be. It could be likely that we would have obtained better results if we allowed the reactions to go for longer than 30 minutes each. We saw that the second and the third trials produced much more rust on the steel wool than the first trial that had the densely packed steel wool. The low experimental value of oxygen contents from trial #1 is consistent with an incomplete reaction between the oxygen and the steel wool. The amount to which the steel wool is packed seems to have a significant impact on the final result; a precise value of the oxygen content of air would be difficult to determine using this experimental procedure. Some possible improvements to this experiment could include …, …, Answers to the specific questions would go here…,

References List the reference here if you have any. As an example, 1.

Zhao, M. Z.; Dragisich, V. General Chemistry Experiments; MacMillan Learning: ISBN-978-1-5339-0949-7, 2018.

2.

Birk, J. P.; McGrath, L.; Gunter, S. K. A General Chemistry Experiment for the Determination of The Oxygen Content of Air. J. Chem. Educ. 1981, 58, 10, 804. https://doi.org/10.1021/ed058p804.

3.

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