Arrange the compounds from highest melting point to lowest melting point.?

Arrange the compounds from highest melting point to lowest melting point.

KI

KF

BN

CH3CH2OH

CH4

I have been stuck on this problem for quite a while and cant seem to get the answer correct.

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  • 4 weeks ago
    Best Answer

    Melting point ranking ....

    You have here a mix of so-called "ionic" compounds which tend to have high melting points, and molecular compounds which tend to have low melting points because of the weak intermolecular attractions between the molecules. And you have one refractory compound (BN), called that because of its extremely high melting point.  We happen to know about BN's high melting point is due to its carbon-like structures, either graphite or diamond, which both have very high melting points.

    Highest MP ................. ............... Lowest MP

    .... BN .... KF .... KI .... CH3CH2OH .... CH4

    Discussion.  As already mentioned, BN will have the highest MP, followed by KF and KI, both soli "ionic" lattices.  By looking at the electronegativity difference we can assume the attraction between K and F will be greater than between K and I. KF will have the higher MP. Ethanol is a liquid, and methane is a gas.

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