Recrystallization - Purify Samples of Organic Compounds That Are Solids at Room Temperature

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the crystals from the funnel to a filter paper, place another piece of filter paper on top of the crystals and press firmly to remove some of the water. Compare the calculated volume of water to the volume of water actually used to dissolve the acid. Calculate the percent recovery of dry, recrystallized phthalic acid.

Observations:

Our observations were that the erlenmeyer flask was heated and then we let it cool down to be able to recrystallize for 10 minutes. It was then filtered then dried. We dried it in a process called “sandwich”. The weight was first 5 mL then added 7.5 mL for a total of 12.5 mL needed to dissolve the phthalic acid. Then it was cooled, vacuum filtered, and washed three times in order to recover the most acid possible. Total amount recovered out of the 1.0 g of phthalic acid was 0.91 g and 0.09 g were lost during the recrystallization process. 0.091 g / 1.00 g x 100 = 91% recovery

Cleaning up:

Proper disposal of equipment is an extremely important part of any lab experiment. Phthalic acid was disposed of properly on a glass container labeled “waste”. Additional materials used were cleaned appropriately and stored away back to their respective sites.

Data and Calculations:

Discussion:

One common mistake in recrystallization is the addition of too much solvent, in this case, water. The amount of solvent can calculated and half of the amount used to start with. Samples are purified through recrystallization. The aim is to dissolve the impure solute from the solution. Crystals will form as the sample becomes more pure. If the compound still had impurities, insoluble materials would be present in the solution and would not dissolve. Filtration was performed and it is used for further separation of the sample from the impurities. Recrystallization was successful in the experiment.

Conclusion:

It was concluded that the water solvent dissolved the solute when boiled and was effective in forming crystals when placed in an ice bath. It was the most suitable recrystallization solvent.