Chemistry 439 - Spring 2008
Lab Reports

 Lab Notebooks - It is absolutely essential that you keep a lab notebook during this class. Since this course is intended to prepare you for a job in a forensic lab, you should be able to see the necessity of documenting what you are doing. Lab notebooks need to be written in ink and they need to have date and time notations in them. This is especially true when dealing with 'unknowns'. Indicate when and where you received them, what you did with them and the results. Dr. Tolley and the TA will be watching to ensure that you are keeping a notebook. Failure to do so will result in deductions from your lab score.
Written Reports - A written report is required to be turned in to Dr. Tolley for each experiment within one week after you have finished the experimental work. It is recommended that you hand your reports directly to him to ensure he gets them in a timely manner. The majority of your grade is based on the lab work, so it is vital to have clear and well-written lab reports. Late reports will be penalized 10% per day.

Lab Report Grading- the breakdown for each lab report will be as follows:

    15% Introduction
    15% Methods
    25% Data
    25% Discussion
    20% Conclusions

Use the following format for the reports:

Title - Use the title in the lab manual
Objective - Carefully study and record what you are trying to do. This is frequently what you should learn from the experiment and what will be asked on tests and exams in one form or another. A few sentences are usually sufficient.
Introduction - Briefly describe the background and theories of the experiment (based on your literature work), what you expect to happen when you do the experiment and why. (Ask yourself what you are expected to learn from each part of the experiment-why have you been asked do each part?). Most of this information can be obtained from your textbook. It is best to write this part of the report before you start the experiment. You should document that you have studied the appropriate chapters of your textbook, and any other literature you need, in order to understand the experiment before you attempt to do it in the lab.
Methods - You may write out or reference (the lab manual for example) the procedures you use but be very sure that you both know and understand them in detail. We recommend that you write the procedures out in advance as a way of learning them and of thinking through each step before you start your experimental work. Many of these labs require you to optimize conditions. Explain how you did this.
Data - Include in the report a copy, an example, etc., of all of the data you collect that is used in any way to explain something or to support a conclusion. Record the data with the right number of significant figures and with the proper units. Data tables are often convenient.
Calculations - It is a good idea to take a trial set of your data and run through a practice calculation while you are planning (preparing for) the experiment. This is a check on your data table as well as your understanding of the calculations. As you do the calculations, be sure to carry all units through to be sure the results have the correct units. An example of each calculation you do should be in the report.
Discussion of your Results - This is where you attempt to convince the reader that you understand all parts of the experiment (you have done your homework), that you did the experiment properly and that your data and the conclusions you draw from that data are reliable. You should explain your data in terms of the appropriate theory. Be sure to address any differences between your results and the expected results, any errors, etc. You may also include ideas, hypothesis, opinions, etc, in this section. This is one of those times when you want to emphasize the strong points and minimize the weak points so be sure that you point out everything you did "right" and what you learned from the experiment. If anything went wrong, that also needs to be explained. In this part of the report, you are "selling" yourself as a potential scientist. Be sure to explain all of your data and especially any results that were not expected. Include an analysis of the errors of any measurements and describe how those errors might affect your conclusions.
Conclusions - Draw conclusions from your data. Explain how confident you are about those conclusions. If the data doesn't tell you the answer with certainty then say so. If you draw conclusions that are unjustified, or if you fail to get the correct conclusions from the data that you have then you will be penalized.

Common errors to avoid
    a) Failure to completely understand the experiment before starting.
    b) Inadequate mixing of solutions or samples
    c) Reading and/or recording data incorrectly
    d) Using contaminated glassware
    e) Incorrect (careless or sloppy) use of pipets, burets and volumetric flasks.
    f) Failure to understand what an instrument (especially the computer-automated instruments) is doing.
    g) Failure to draw appropriate conclusions from the data.