Question

How to determine your how much pure your aspirin is in aspirin synthesis lab? Please give a lot of details.

Answer 1

Purity check for Aspirin

Aspirin with a melting point of 135 oC, can easily be tested for its purity. The sample melting point If is within 135 +/- 1oC range with the literature melting point, then the sample of aspirin is pure. If impure, the melting point would be seen much lower than 135 oC.

Other methods are more time consuming, a C, H, N analysis of the sample will also tell how pure the sample is. FeCl3 test is also one way to check if the sample has the starting material salicylic acid impurity left in it, just add few drops of freshly prepared FeCl3 solution to the sample of aspirin, apprearence of orange color proves aspirin is pure. However, appearence of purple or reddish coloration indicates presence of salicylic acid in the sample of aspirin.