Recrystallization
Results and Discussion – Expt. 3 (Crystallization) Name:
Parts A and B:
1. Please comment on the relative purity of your recrystallized salicylic acid (Hint: You should use your empirical data to support your claim).
-The Salicylic acid that I obtained had a melting point range around 157-158 degrees Celsius for Part A. For Part B the melting point range was 156-157.5 degree Celsius. Part B, I would say the sample is less pure because of the notion that impurities lower the melting point. Since part A ‘s melting point was higher and closer to the melting point of the pure sample, it was more pure. 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 close to the melting point of my pure sample so I would conclude that it was quite pure.
2. Suppose you were performing a recrystallization 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 recrystallization 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?
1-
3. How did your % recovery for the Craig tube recrystallization of salicylic acid compare to the one you performed in part A of this experiment? Did this result correspond with your expected % recovery (as
Parts A and B:
1. Please comment on the relative purity of your recrystallized salicylic acid (Hint: You should use your empirical data to support your claim).
-The Salicylic acid that I obtained had a melting point range around 157-158 degrees Celsius for Part A. For Part B the melting point range was 156-157.5 degree Celsius. Part B, I would say the sample is less pure because of the notion that impurities lower the melting point. Since part A ‘s melting point was higher and closer to the melting point of the pure sample, it was more pure. 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 close to the melting point of my pure sample so I would conclude that it was quite pure.
2. Suppose you were performing a recrystallization 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 recrystallization 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?
1-
3. How did your % recovery for the Craig tube recrystallization of salicylic acid compare to the one you performed in part A of this experiment? Did this result correspond with your expected % recovery (as