Question

Aspirin that has been stored for a long time may give a vinegar odor and give a purple color with fecl3. what reaction would cause this to happen

Answer 1

Reaction of phenol with FeCl3 would give a purple color

Step-by-step explanation:

Aspirin is essentially 2-acetoxy salicylic acid. Thus the chemical structure comprises a benzene ring along with 2 functional groups: a carboxylic acid (-COOH) and a acetoxy (-OCOCH3) group.

Hydrolysis of aspirin results in the cleavage of the acetoxy group to form CH3COOH acetic acid which gives a vinegar odor. Additionally this creates a phenolic structure (phenol group) which reacts with FeCl3 to give a purple color.

Answer 2

There would be production of acetic acid from moisture that gets inside the bottle. What happens is that water molecules reacts with the aspirin protonating an oxygen in the acetic group and allowing it to detach from the molecule producing acetic acid which is the main cause of the vinegar smell.