Very quick question regarding melting point and purity

[daselocution]

Homework Statement

For the following melting point, indicate what might be concluded regarding the sample purity:

Melting point: 147ºC (dec.)

Homework Equations

I assume that (dec.) means that the sample decomposed.

The Attempt at a Solution

I am wondering if this means that the sample is practically 100% pure because it decomposed in such a small temperature window, or if the fact that the sample decomposed means that no useful information can be obtained.

 

[chemisttree]

I would say the latter unless you know something more about how a pure sample of the analyte should behave. If it is supposed to melt and it decomposes, you have a reactive impurity. In my experience, reactive impurities mean strong mineral acids or oxidizers.