error in destroyer?

[OU11BB]

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The question is which has the highest melting point. There are several hydrocarbons listed propane,butane, pentane, 2 methylbutane, and neopentane. I read in MCAT hyperlearning that increased branching lowers BP and MP. With that in mind the answer should be pentane. however in destroyer it wants you to answer neopentane. My reasoning is increased molecular weight, increased hydrogen bonding will raise MP and BP, decreased molecular weight, branching, hydrogen bonding will lower MP and BP. Am I right or wrong. Also the weak forces(van der waals) are not as significant when there is branching so the compounds are not as attracted to each other. Is that right or wrong?

 

[wantVCUdental]

The question is which has the highest melting point. There are several hydrocarbons listed propane,butane, pentane, 2 methylbutane, and neopentane. I read in MCAT hyperlearning that increased branching lowers BP and MP. With that in mind the answer should be pentane. however in destroyer it wants you to answer neopentane. My reasoning is increased molecular weight, increased hydrogen bonding will raise MP and BP, decreased molecular weight, branching, hydrogen bonding will lower MP and BP. Am I right or wrong. Also the weak forces(van der waals) are not as significant when there is branching so the compounds are not as attracted to each other. Is that right or wrong?

Destroyer is correct, in considering the melting point of a substance, what you are thinking of is correct, but what is an even more important factor is the ability of that molecule to form crystal. A crystaline molecule has a greater melting point than a linear molecule. Therefore neopentane mp>pentane 😛

this rule does not apply to boiling point of a substance.