Question

how does the melting point of an impure compound compare to the literature melting point? Briefly explain the chemical principle (in terms of structure and intermolecular forces) behind this observation

Answer 1

Melting points are sensitive to the purity of the organic compound, since the crystal lattice of the compound is disrupted by the prescence of an impurity

check out this site for more: http://www.foothill.edu/psme/armstrong/meltingpoints.shtml

Answer 2

Was it any good?

Answer 3

@DylanGR1997 hello! thank you for that. I understand, however unsure how to answer the question in terms of structure and intermolecular forces.

Answer 4

I'm trying to figure it out

Answer 5

Melting point decreases, this is because a crystalline compound is able to contain more precise packing than that of an impure mixture. Closer packing means stronger intermolecular interactions.

Answer 6

A pure compound can develop a symmetrical pattern that has optimal intermolecular bonds, hence a more stable structure. Entropy may seem like an opposing factor to this

Answer 7

but the presence of impurities in the crystal actually requires increased order shells to occur around the impurities, which actually increases entropy and therefore is unfavoured

Answer 8

These properties also apply to liquids

Answer 9

Do not hesitate to inform me if you have any confusions in regards to my response I would be happy to assist you further in understanding this concept.

Answer 10

http://en.wikipedia.org/wiki/Crystal_structure I recommend looking at this it is fairly decent at explaining the gist of crystal structure.