Physical Chemistry Laboratory - Lab Reports | CHEM 461, Lab Reports of Physical Chemistry

Download Physical Chemistry Laboratory - Lab Reports | CHEM 461 and more Lab Reports Physical Chemistry in PDF only on Docsity! 1 461 LAB REPORTS 0. Title Page Experiment number. Experiment title. Date. Your name. Big font. I. Introduction 11 points (up to 3 pages, less is better) Concisely describe what the experiments are to achieve. Show that you know the physical and chemical concepts behind the measurements and the apparatus, and introduce any theoretical calculations that will be necessary for data analysis in Section III. Do not merely parrot back the section of some book. If you need to use equations from a book, be sure you have changed the variables to be consistent with your experiment and the rest of your writeup. Numbering each equation makes it easier to refer to it from the Results section. You can show you’ve read the background material by simply referencing it correctly! Do not reproduce diagrams of the scientific apparatus. There is no need for excessive padding. Example: "In this experiment, temperatures were monitored with a thermistor, whose resistance (R) changes sensitivity with temperature (T). According to Mermin [5], over a limited temperature range most resistors behave: R = aT + b , (3) where a and b are constants ...." If this equation is needed later, it can simply be referred to as "Eq. (3)." II. Experimental 3 points (1 page, less is better) Simply reference the handout, noting differences in actual procedure used and why you might have changed the procedure. Do NOT give a step-by-step description of what you did in the lab. Do NOT quote from the lab handout (we’ve read it already). Do refer to the handout and include it in your References section. For example, "The experimental procedure has been described elsewhere (reference), except for the following modifications." III. Results and Discussion 60 points (up to 10 pages) This is the most important part of your report. In this section, you need to describe CLEARLY how you turned your raw data into the results that are asked for in the lab handout. Include in this section an example of each calculation you have made, and then a summary of all the data after that particular calculation. Most values you report in these labs will be subject to some uncertainty. In addition to the sample calculation involving data manipulation, a corresponding sample calculation involving error propagation to determine uncertainties should be included. 2 Without these two main pieces of information, the reader (i.e., the TA) will be unable to see how you turned your data into results. Your score on this section of the lab will directly reflect the readability of this section. Talk to your TA if you have questions about the calculations required or the error analysis. Each lab requires a different handling of the error. You should refer to equations from the Introduction by number, and tell the reader where in the Appendices all sample calculations may be found. Experimental results should be accompanied by literature values whenever possible. The handout will often ask you to compare your results to the literature so that you can determine whether or not your experiment and/or model employed for data analysis are reasonable. In this section you should think about your data, the model, the experiment and the literature to see what they are saying about each other. It is less important that your experimentally determined values are accurate than that you have a good understanding of how your errors arose. Here is how Charlie Campbell does it: • Start with first Figure or Table of "Raw Data." Describe exactly what the experiment was, and then introduce the data. Example (GC): "The retention time (tr') of propylene was measured as a function of column temperature between 100 and 300°C. Fig. 1 shows the results." • Now qualitatively describe the data, then quantitatively describe any important features: "As can be seen, the retention time decreases smoothly with increasing column temperature. The retention time decreased from 3 minutes to 0.1 minutes in this temperature range." • Now remind the reader of any theoretical relationship which might be useful to explain the data. Refer to this with a title if possible, and an equation number from Introduction. EXAMPLE: "The Mickey Mouse relationship (Eq. l) predicts that ln (retention time) should vary inversely with the column temperature (Tc)." NOTE: As you write the Results and Discussion keep two pieces of paper at hand, labeled "Intro." and "Conclusions." As you come across theoretical relationships required, jot these down in order on the "intro." list. Do the same with major "Conclusions" on their list. Use lists as outlines later for writing "Introduction" and "Conclusions." (You may want to make a list of "Experimental Details" to add to "Experimental" section also.) • Now introduce a plot of your data against the theoretical curve, using axes appropriate to theory. EXAMPLE: "Fig. 2 shows the data of Fig. 1 replotted as ln (tr'/min.) versus 1/Tc, together with the best least squares straight-line fit to the data predicted by Eq. 1. The slope of this line is (20 ± 2°C) and the y-intercept is -(121 ± 12)." • Now qualitatively and then quantitatively describe the quality of fit, and explain any major discrepancies. "The fit to the data is rather good, with a correlation coefficient of 0.95. The major deviations are at very short retention times, where the relative error in