Recrystallization Report

Please access the class lab web site http://mason.gmu.edu/~sslayden/Lab/sws/315/chem315.htm and read the link "Lab reports – General" under the Reports heading. As for the previous report, the written report will be constructed from a series of your answers to the questions below.

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.

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.

Use the same number for each of your answers to correspond to the question number -- include the numbers and section headings in your report.

Introduction:

1. There were two main parts to this experiment. Briefly explain the purpose/goal/objective of each of them. (The three terms in the preceding sentence are essentially synonymous, but it may be easier for you to focus on just one of the words. The statements should not only be about what you did, but also why you did it.)

Procedure and Results:

2. Explain how you determined the best recrystallization solvent.

3.Briefly state the basic steps in the recrystallization of a solid sample. Use a separate bullet point for each step. Use correct terminology throughout. Be sure to include statements regarding the importance of solution temperatures, where applicable, in each of the steps.

4. State what you observed when you explain what you did in 3., above (e.g., after adding the boiling solvent, all the solid sample dissolved, or after adding the boiling solvent, the solid did not dissolve immediately but required additional heating and stirring, etc.).

5. State the quantitative results of the recrystallization, that is, the % recovery of the solid sample. Comment on your percent recovery. Explain why 100% recovery cannot be achieved.

6. State the results of your melting point determination. Comment on what your melting point range indicated about your sample's purity. Make a comparison of your purified sample's m.pt. and the literature m.pt.

Discussion/Conclusion:

7. Briefly summarize the conclusions reached in Results. DO: relate your results back to your purpose (and perhaps re-write your purpose if it does not relate well here). DO NOT: repeat what you have written above - this is a summary.

Remember, 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. Be sure your conclusions reflect what you actually did in the experiment.

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 error was. Human error, such as "I may have forgotten to add additional solvent" is not an acceptable explanation (unless that is what happened in which case it should be incorporated in the report). "I broke the flask containing the recrystallized product, but I managed to recover most of it from the benchtop", is acceptable.