Question

What is an "evacuated melting point" and why would it be taken over a standard melting point measurement?

Answer 1

When the melting point is measured in an evacuated melting tube , the temperature obtained is called as evacuated melting point.

Usually the substance whose melting point has to be determined starts to decompose in the presence of oxygen , even before its melting point is reached. In such a case the false melting point is obtained , and also the substance cannot be reused.

So the evacuated melting tube eliminates this problem ,as the substance then cannot decompose in the absence of oxygen and it can also be reused and it gives accurate melting point determinations.