Originally Posted by starrysky
Rank from highest to lowest melting points:
KBr, SiO2, NaCl, CH3CH2CH3, CH3CH2OH
I can't give you a full answer but note that we have different types of bonding here: SiO2 bonds covalently; NaCl and KBr are salts and bond ionically; and the last two, propane and ethanol are hydrocarbons, which tend to bond somewhat weakly. That would be my guess for the ordering but I'm not positive on the relative strength of the ionic vs. hydrocarbon bonding. You should be able to look up the specific chemicals to find out, though.