How to be a Successful Organic Chemist

37 Your data may not always support the expected outcome of an experiment. For example, your data may indicate that no reaction took place, or a product was very impure, and so on. These types of interpretations are appropriate as long as they are based on actual observations. An example of a data interpretation that does not support the expected outcome is when you call atten- tion to an OH peak in the IR spectrum that is not consistent with the structure of the desired product.That should be addressed, and a likely scenario to explain the presence of that peak should be provided. (2) Things to watch out for: Unfocused or off-topic interpretations. Examples: interpretations that dis- cuss what you learned, experiences you had or comments about your success as a lab student. None of these examples relates to the purpose of the experiment, and none of them deal with the objective data you col- lected. The interpretation should not deal with unimportant or irrelevant observations. For example, if you say that the IR spectrum did not show the correct peaks because you collected the spectrum in a wrong way, that becomes a meaningless statement (how is it possible to collect a spectrum wrong, how do you know it is wrong, and why did you not address that issue if you knew about it?). Here are some other examples with speculative conclusions that should be avoided. • I weighed something wrong, or the scales were wrong • The yield was low because I transferred the sample between vials • The glassware used has a high degree of uncertainty Furthermore, any error must have a direction and observations cannot contradict themselves. If we come back to the example above with the OH peak that was found in your IR, that should not be there, surely that must mean that your yield also cannot be correct. And what about your melting point? That must also be off, or broader than it should be. (3) Some examples: Bad (imprecise, does not refer to specific data, no clear connection to the purpose of the experiment): The yield was higher than I wanted because of impurities and I weighed the sample wrong. The IR does not show what I should have because of something happening during the collection of the spectrum that should not have happened. The cylinder I used to measure was wet so that led to not getting correct data. Bad (does not refer to any specific data, does not connect data to the purpose of the experiment, irrelevant): IR spectroscopy is used to saying something about which functional groups are found in an organic mol- ecule. It can be used to find bonds that correspond to different functional groups. In my molecule, I have many bonds, and that can be seen in the spectrum. Furthermore, I have some strong peaks, and some weak ones, which is to be expected. Good (Discusses specific data, interprets these data to support specific conclusion that relate to the pur- pose of the experiment): The yield was higher than expected (104%) due to alcohol contaminants in the isolated product. This is evident from the IR-spectrum of the sample (O-H stretch at 3551 cm -1 ), which is a bond not present in the product. The melting point mirrors this (74.1 ° C - 84.9 ° C), as it is broader than expected (81.5-85.0 ° C) 1 . 1. Correct citation to a literature source for the melting point.