Melting Point Report
Most of your answers should be several sentences – do not attempt to "explain/discuss" in just one sentence. More and simple declarative sentences are better than one long convoluted and complicated sentence. Assume the reader of your report is an educated scientist (and so you do not need to waste time with "dictionary definitions" - any needed definitions should be incorporated as part of a sentence. Do not quote the Manual or text -- paraphrase these sources as necessary.
Please type your report with double-spacing, 1" margins all around, and 12 pt font. Print one-sided only.
Staple together the completed Report Form from the Manual (as the first page) and then the written report.
Number each of your answers to correspond to the question numbers below-- include the numbers and section headings in your report.
1. Give a brief statement (a few sentences) explaining the purpose/goal/objective of the Melting Point experiment. (The three terms are essentially synonymous, but it may be easier for you to focus on just one of the words. The statement should not be only about what you did, but also why you did it.)
2. Explain how a melting point range is determined experimentally and why this experiment does not determine a melting "point". What is a "literature" melting point?
3. Explain how a too-great rate of heating could affect the accuracy of the melting point range. Explain why a small sample size is desirable.
4. Explain how the observed melting point range is an indication of purity of a substance.
5. Discuss the significance of a mixed melting point in determining the identity of an unknown substance.
Procedure and Results:
6. Briefly describe the steps in the experiment, using a separate bullet point for each step (e.g. "determined the m.pt. of known....", not "I obtained 4 capillary tubes...").
State your m.pt. results for each step, above.
7. Discuss the quality of your melting point measurements of the knowns with respect to their ranges, as you explained in the Introduction. Compare numerically your melting point ranges of the known compounds with their reported literature melting points.
8. How did you initially narrow down the identity of your unknown compound? (Did you narrow it down to one compound or could two compounds reasonably have been good candidates? Explain.) How did you determine the final identity of your unknown compound? How did you decide which compounds to test as mixed melting points?
9. What did the mixed melting point procedure for your unknown indicate? If you did not do a mixed melting point on your unknown, explain why. Explain what you would have learned from doing a mixed melting point with your unknown.
10. Briefly summarize the conclusions reached in Results and Discussion. DO: relate your results back to your purpose. DO NOT: repeat all the discussion points.
Experimental results will be graded as part of your report - a small component of your grade. It's more important to accurately report and discuss the results you obtain than to get the "right" answer. Be sure the data you report reflects your actual experimental findings. Do not try to cover up error or "hand-wave" it away. Be sure your conclusions reflect your real data.
If something went wrong with your experiment, then state so, and explain as best you can what might have caused the poor results. "Experimental error" is never an explanation unless you can state what the experimental error actually was. Human error, such as "I may have mis-read the thermometer" is not an acceptable explanation - it sounds more like an excuse.