There are a few general rules that apply to scientific writing, especially the journal article, the loose model for this course’s reports. It is very important that you keep these in mind when working on the purpose or discussion.
One rule is to always write concisely. Extreme verbosity is not desirable, this means avoiding flowery language and including only material relevant to a given section, weather it is the purpose or the discussion. Second, clarity is important if scientific writing. For example, when using a pronoun, make sure that it is perfectly clear which noun the pronoun refers to. Third, write the report like a professional chemist. Avoid phrases like, “the purpose of this experiment was to introduce kinetics to the class.” An appropriate purpose would be, “Today we will investigate the alkylation of sodium saccharin with iodoethane using the melting point to determine the major product.”
You must maintain your laboratory notebooks as your ONLY notebook. All writing in your notebooks must be in pen and should be signed and dated.
Purpose Tips
The purpose should be to resemble the introduction to a scientific journal article, but with a much narrower scope and exclusion of references to relevant literature. Most importantly, you need to state the problem clearly (i.e. what is the ‘purpose’ for performing the experiment; what knowledge do you hope to gain?) You should also briefly talk about the approach you’ll be using (e.g. ‘the effect of temperature on battery operation will be studied using a zinc and cadmium electrochemical cell) and the values of interest you hope to ascertain (e.g. “the change in Gibbs free energy at standard state conditions will be determined”.) As the example demonstrates, mention the chemicals being studied or acting as the primary reagents.
Discussion Tips
In journal articles, very often there is a section called “Results and Discussion”. Keep in mind that your report sheets, where you present your results, are closely related to the discussion. The discussion is not the place to rehash the theory or summarize the procedure. It constitutes the culmination of the scientific method: your hypothesis is proven viable or not. It is about conclusions, whether you make a useful discovery or divide a procedure is invalid. Its purpose is to expand on your observations and discuss what may have caused bad results.
Therefore, you need to evaluate your results. Are they ‘good,’, ‘bad’, precise, accurate, too high , or too low? What is the significance of your results, if any? What are the limitations of your results? What are possible errors?
In discussing errors, it is often helpful to refer to the percent error or deviation from an accepted value. However, do NOT merely list possible errors (for example, “Too much solvent may have been added to the volumetric flask”). You should DISCUSS the errors that may have shifted an otherwise reasonable answer in the direction of an erroneous one. Also, if you use an equation to arrive at your final result, comment on how different variables could have affected the final result. For example, “…a larger mass will result in a higher value for the molecular weight”.
There are more questions to consider when you are evaluating the experiment. What trends did the data show? If there were no trends, but you thought there should have been, discuss that also. Reflect back on the purpose of the lab – was the goal of the experiment achieved? Why or why not? How could the technique used be applied to other situations? Why was your method more or less suitable than other available (e.g. determining concentration by titration rather than by using an absorption spectrometer). How might you change the procedure to obtain better results?
If you would like additional help writing your report effectively, try consulting the American Chemical Society Style Guide: A Manual for Authors and Editors (especially pages 1-17) edited by Janet S. Dodd, which is on reserve in the chemistry library. Also, you may find it helpful to read an article in the Journal of the American Chemical Society as an example.
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