What's up everybody. I was wondering about a question I have had for quite some time. I know that for an impure substance, the melting point is always lower that that of the same substance in a pure matrix, even if the contaminant has a higher melting point. I have a couple of questions.
First, does the identity of the contaminant matter in determining the melting point depression? For example, let's say a NIST standard of MDMA is acquired (far-fetched scenario) will 99.00% MDMA with 1.00% sugar melt at the same temperature as 99.00% MDMA with 1.00% reaction byproducts from a Pd/C CTH?
My second question is, does the melting point depression follow any sort of linear or other mathematical function when compared to the percent purity? Perhaps a curve could be made that related percent purity to melting point by using triple recrystallized sample and making 100-50% standards, and taking their melting points. For example for cocaine or heroin, when buying big amounts, the difference between 80% and 95% is very important.