During the semester you will be asked to develop various aspects of your scientific record keeping and report writing. These talents will hopefully be expanded and built upon during subsequent chemistry and other science lab courses. The exact documentation requested for each laboratory exercise is explained at the end of each experimental write-up.
Before you arrive in the laboratory to perform a given experiment it is essential that the experiment be studied carefully, with special emphasis on the overall experimental design and on the general flow of the procedure. The laboratory will run smoother and more safely if everyone arrives prepared. Occasionally, it will be necessary to make changes in a given procedure. These changes will be brought to your attention early in the lab period; please note them immediately in the appropriate place in this manual.
Prior to starting an experiment, a researcher will often clearly record her/his objectives in an attempt to clearly define the purpose of the experiment in order to best design procedures that can achieve these purposes. We will ask you to prepare for each laboratory experiment by reading the lab handout and then by writing a short objectives section prior to arrival at lab. A sample objective section for an experiment might be:
Volume Calibration of a Kimax Buret and Density of a Metal
In this laboratory, I am going to establish a calibration curve for a 50.0 mL buret. Each buret is slightly different and the volumes they deliver may or may not agree with the volume markings. I will determine this by dispensing volumes from the buret and then correlating these volumes to their actual volumes by weighing the dispensed amounts and converting the determined mass to volume by knowing the density of water at room temperature. (This value is 0.998204 g/mL.) Linear regression will be used to statistically treat the data. In the second portion of the experiment I will determine the density of a metal by measuring its volume and mass. Again, the data will be treated statistically to determine the accuracy of my measurements.
For at least one laboratory, you will be asked to prepare and submit a document in the form of a laboratory notebook. In official laboratories (for example, industrial or research labs) where documentation is critical, it is customary to record experimental events directly into a bound notebook with dated and numbered pages. The flow of information for a particular experiment should tell a story – it should have an opening, a plot, and a conclusion. When complete, the documentation should provide a second reader a clear understanding of what happened in the experiment and should include all the necessary information to permit the reader an opportunity to repeat and validate the experiment. Through the years, the scientific community has established a standard sequence to laboratory reports; it is:
- Title: A concise, specific, and descriptive title for the experiment.
- Objectives: A brief statement about the experiment and what you plan to accomplish (what you wish to accomplish) in the experiment. Your objective is not “to learn how to….” but to do something. (See example.)
- Procedure: A list or narrative of the steps you did in performing the experiment. Your experimental record should be complete enough to permit someone else to perform the same experiment in the same way.
- Observations: Your record of measured data and observations.
- Results: A section where results are calculated and presented in tabular form.
- Discussion: A section to show how you analyzed your results and to present a discussion that eventually leads to a conclusion.
- Conclusions: A final paragraph should summarize the conclusions of the study. This section is also where you can mention future work that you would like to do to follow-up this experiment and where you can discuss errors and uncertainties associated with your results and conclusions.
Instead of a notebook we will provide worksheets. You should treat these write-up sheets as your laboratory notebook for these experiments. All primary data should be recorded directly onto your write-up as you do the experiment.
For one laboratory report (the glucose lab), you will be asked to prepare a report in scientific journal form. You should review chemistry journal articles in preparation for preparing this report to see what needs to be included and how data are presented.