1. Determine the percentage of aspirin (acetylsalicylic acid) present in aspirin
ID: 996327 • Letter: 1
Question
1. Determine the percentage of aspirin (acetylsalicylic acid) present in aspirin tablets. Can you
make any statements about the other materials aside from aspirin that must be in the tablets
based upon what you observed in this laboratory ?
2. Predict a melting point if you combined and mixed 10 mg each of the three reference samples
for solubility (naphthalene, benzoic acid and benzophenone). Provide a statement that
supports your prediction.
3. If you dissolve 975 mg of aspirin (the amount in three tablets) in boiling water to form a
saturated solution and cooled to room temperature followed by filtration to collect the
crystallized aspirin, what mass of aspirin would you expect based on your measured values
of aspirin solubility? If you took the mass of aspirin that you calculated from the water
crystallization and formed a saturated solution in boiling ethanol and allowed the solution to
cool and collected the crystals at room temperature what mass of aspirin would you expect
from the ethanol crystallization? For both of these compare to the masses actually obtained
in the lab for these two procedures and comment if the masses are similar or not. If not
similar give a reasonable explanation as to why this might be the case.
4. Explain why aspirin is more soluble in ethanol than in water.
Please answer all questions "Crystalization lab "
Please Help :) Thank you !
Explanation / Answer
ANSWER : According to the reaction
C6H4(COOH)(OH) + (CH3CO)2O ---------------------> C6H4(COOH)(OCOCH3) + CH3COOH
salicylic acid Acetic anhydride Acetylsalicylic acid (Asprin) Acetic acid
To calculate percentage of aspirin, we go as under
other materials of the reaction are Acetic anhydride the reactant and acetic acid the product
138 g of salicylic acid gives --------------------- 180 g of aspirin
hence for 100 ----------------------- = ?
Therefore percentage = (180 x 100 ) / 138 = 130.43g = 13.4%
The other materials present in the solution are, acetic acid which can be removed by adding water in which it is more soluble , than aspirin.
when aspirin is dissolved in reference samples its melting point decreases.
Aspirin molecule is made up of a benzene ring, a carboxyl group and an ester ,it has both polar and non-polar components, thus it is slightly polar . We have learnt that like dissolves like, water being highly polar it is slightly soluble in water when compared to ethanol which is slightly polar like aspirin.
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