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Experiment 1: Recrystallization of Acetanilide Using Decolorizing Charcoal
I
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II
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The process involved first dissolving the acetanilide by
heating it
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Cool it down
to prevent frothing when adding the charcoal
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Add spatula-point of decolorizing charcoal (it is
responsible for removing the impurities as charcoal bonds with colored organic compounds)
then heat it again
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Crystallization is used to purify substances because the
molecules of a specific compound arrange themselves in a certain way that different molecules
of different compounds do not fit or do not bind to the compound in the same way
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Precipitate forms when the solution is cooled too quickly, that is why it must be cooled to
room temperature first
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Furthermore, the compound should only be
moderately soluble to the solvent to minimize sample loss
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Finally, cover the flask
to prevent impurities going in as well as evaporation of solution leading to sample loss
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To form crystals faster, scratching the inside of the
Erlenmeyer flask with a stirring rod may be opted as a really small part of the glass would be
removed from the flask and the crystals would then attach to that glass shard
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III
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4°C
15
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57g
1
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00g
50
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58g – 14
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01g
(Final weight/ Initial weight) x 100 = % recovery
(1
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00g) x 100 = 50
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4°C
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5%, which is not a

desirable value because a higher value would mean a more positive result
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g
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The result that was shown through the percent recovery is that only
about half of the original substance was restored, and so not fulfilling the goal of obtaining a
high percent recovery of pure crystal acetanilide
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Summary
Recrystallization was done to recover pure acetanilide in the form of a crystal from a
contaminate acetanilide by using decolorizing charcoal and the process of filtering to remove
its impurities
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4°C and 50
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V
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The solubility of Acetanilide in water at 100°C is 5
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53g/100mL
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2g of acetanilide from 163mL of water
(assuming the solution is chilled to 0°C)?
(163mL x 0
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8639g
5
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8639g = 4
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3361g / 5
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39% recovery
* 5
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Refer to your answer in the Prelab Question #3, Does this suggest that adsorption of
charcoal is exothermic, or endothermic? Explain
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There is also a force of attraction existing between the absorbate and the adsorbent,
which releases heat energy, thus this is an exothermic process
3
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The solubility of B in ethanol is
20g/L at 100°C and 0
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In order to crystallize 15g of B from ethanol you
will need 75liters/1liter/750mL/75mL of solvent
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After cooling 0
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5g/14
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The ideal
%recovery for this recrystallization is 99%/19
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5%
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Therefore, water is a better/worse
recrystallization solvent since the percent recovery from water is 100%/33%/67%
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85g, 99%, Worse, 67%
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5
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Upon crystallization at 20°C, 95
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Calculate the solubility of the organic compound in water at
100°C and 20°C
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80g/100mL
20°C=0
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7% with 7 to get the grams recovered
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699g would then be subtracted to 7 to obtain the g sample lost due to it
being dissolved
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301g was then divided by 103mL to get the solubility
per mL
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References
[1] Guidote, A
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Experiencing Organic Chemistry
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Print
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AdiChemistry
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p
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d
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29, June 2013
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adichemistry
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html>
[3] “Crystallization | Your Mother Was a Chemist
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n
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, n
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Web
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< http://kitchenscience
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com/crystals>



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