Recrystallization

The pure Salicylic acid that I got the melting point for had a range from 158-159 degrees Celsius. The impure was 157-158 degrees Celsius. The temperature for my impure salicylic acid was strange in that it was close to the melting point of the pure salicylic acid. One explanation presented was the possibility of obtaining a relatively pure sample from the impure sample. Maybe the impure bottle was not mixed well and I Just so happened to grab the sample that was still relatively pure. The melting points of both part a and part b samples were fairly lose to the melting point of my pure sample so I would conclude that it was quite pure. 2.

Suppose you were performing a rationalizations and you had Just added the optimal amount of boiling solvent to dissolve your impure solid… But then you a squirrel ran by and you decided to chase it. When you got refocused and returned to your experiment, you realized that you’d left your Erlenmeyer flask containing your rationalizations solution on the hot plate for too long. (1) How did you know that you’d left your flask on the hot plate for too long? And (2) how can you correct your mistake? – 3. How did your % recovery for the Craig tube rationalizations of salicylic acid compare to the one you performed in part A of this experiment?

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Did this result correspond with your expected % recovery (as compared to part A)? Why or why not? -The percent recovery differed quite a bit from Part A to Part B. In part A I obtained 67% of Salicylic Acid where as in Part B I obtained 45%. This is a difference of 22%. In Part A we used an Erlenmeyer flask and the beginning sample size was 0. 103 grams. From this we crystallized our sample and separated our desired product by meaner of scum filtration. This introduced possible errors. The possibility of a transfer error like not transferring your entire product from the Erlenmeyer flask to the Hirsch funnel could have occurred.

In part B, I was expecting to obtain a greater recovery process would separate the solid and the liquid better than the vacuum filtration because the centrifuge spun the sample at a high speed and thus the centrifugal force separated the substance part C: 4. For each of the solvents you tested in Part C (methanol, water, and toluene), (1) riffle describe your results, being sure to comment on the suitability of these solvents as rationalizations solvents for fluorine and (2) briefly explain these results, using (at least) relative polarity as a criterion for explanation. . Methanol – b. Water- c. Toluene – Melting Point Determination: 5. We discussed in class how AMP is used to characterize the purity off solid. Answer the following questions about melting point: a. What is always true about the melting point of an impure solid (relative to the pure compound)? B. Please briefly explain what you described in part a.

Jesse
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