[izack_ben]

Good evening!

i just have a few questions regarding boiling points and melting points? I really don't have any idea about the answers..

1. Is it advisable to use the temperature of solidification as the melting point of a solid? why?

2. What would be the effect of each of the following conditions on a malting point determination?
    a. presence of insoluble impurities
    b. incomplete drying
    c. temperature raised too rapidly

thank you...

[sondakem]

1. Is it advisable to use the temperature of solidification as the melting point of a solid?
    No.  Many compounds tend to super-cool.

2. a. presence of insoluble impurities
No effect on MP but you may have trouble deciding on the melt temp
    b. incomplete drying
        If the material is soluble in the solvent, it may begin to dissolve and look like a melt
        If the solvent interacts with the compound, such as hydrate formation, you get the MP of the "new compound"
        If the solvent evaporates before the MP it will leave the "pure" compound which should melt normally
    c. temperature raised too rapidly
        The MP observed will be too high because it was not observed at a near equilibrium condition - temperature overshoot