Lab Exam 1 (Part 2/3) Synthesizing Aspirin
the same student mixed the crystalline product with ethanolic 1% FeCl3 solution and obtained a colored solution. briefly explain what might have caused this result.
FeCl3 is used to indicate the presence of a phenol group by producing a purple color. In this experiment, the crystalline product turned colored as a result of still having salicylic acid present because it contains a phenol group. It can be a result of improper heating.
alcohol group
-C-OH
a student who was in a hurry to complete this experiment didn't completely dry the crystalline product before the final weighing. how would this error affect the calculated percent yield of the experiment
Not drying the crystalline product will cause the final weighing to be higher than it should be and possibly higher than the original mass of salicylic acid which is impossible. It would cause the % yield to be too high and possibly over 100%.
the student in (1) didn't bother to cool the water used to wash the crystals. how would this error affect the calculated percent yield of the experiment?
Not using chilled H2O to wash crystals will cause the yield to go down because warm H2O may dissolve the crystals where chilled H2O keeps it in crystalline form. The percent yield would be lower than it should be.
Briefly explain the purpose of the FeCl3 test. What does a positive FeCl3 test signify? What observation corresponds to a positive FeCl3 test?
Phenols form a violet complex with Fe(III), which is intensely colored. This is the basis for the test. purpose is to determine presence and absence of phenols positive FeCl3 test signify means presence of phenols in the given compound The formation of a red, blue, green, or purple coloration indicates the presence of phenols. ------------------------------------------ negative test: yellow solution, no phenols present
a deiccant, or drying agent, is often added to aspirin in order to prolong the aspirins shelf life by delaying hydroloysis. How can you easily determine whether or not any aspirin you have at home has begun to hydrolize
The hydrolysis of aspirin yields, Acetic acid and salicylic acid, the smell of the acetic acid could be a good indicator that aspirin has begun to hydrolize. smells like vinegar.
reagent
a substance or mixture for use in chemical analysis or other reactions.
chemical formulas for the formula for creating aspirin
c7h6oc + c4h6o3 <---> c9h8o4 + c2h4o2 [first ring] [third has ring]
phenol group
inside is full circle I think
product
new material formed in a chemical reaction
esterification reaction
reaction between an alcohol and an anhydride (carboxylic acid) leading ot formation of an ester
formula we used for creating aspirin
salicylic acid + acetic anhydride <--> acetylsalicylic acid + acetic acid
Ester group
second R is CH3
carboxylic acid group
usually 'oh' in corner ...-C=O I OH
