Question

Posted by ann on Sunday, October 17, 2010 at 4:26am.


In melting point determination, why shouldn't a substance be re-melted? (i.e. why should we not re-melt a substance that has previously been melted in a melting point tube?)

Answer 1

I think the original melting process may drive out some of the impurities in the sample and those condense in the upper part of the tube; therefore, taking the m.p. a second time means we are using a "different" sample. (But I've done that. ;-)]