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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: nemzy on January 17, 2005, 02:09:31 AM

Title: hydrocarbons and heat
Post by: nemzy on January 17, 2005, 02:09:31 AM

A hydrocarbon that has lots of double bonds takes more energy to melt, so therefore takes more heat than a hydrocarbon with less double bonds right?

so a hydrocarbon with no double bonds will require the least amount of energy, so the last amount of heat

is my concept right?

thanks

Title: Re:hydrocarbons and heat
Post by: movies on January 17, 2005, 02:26:46 AM

This depends on a lot of different factors, including crystal structure.  I don't think that your assumption is necessarily true for all compounds.

Title: Re:hydrocarbons and heat
Post by: Mitch on January 17, 2005, 02:52:34 AM

Ethene will take less energy to melt than octane. Be careful how you order these things.

Title: Re:hydrocarbons and heat
Post by: nemzy on January 17, 2005, 08:28:36 PM

ok, well here is the exact details of the problem:

which fatty acid melts at the highest temperature (solid to liquid)

(order from lowest to highest temp required to melt)
Don't know how to draw on here, so i will just explain it to you

1) a 17 long hydrocarbon chain with a Carboxyl group attached at the end.  Has no double bond

2) a 17 long hydrocarbon chain with a Carboxyl group attached at the end.  Has 1 double bond

3) a 17 long hydrocarbon chain with a Carboxyl group attached at the end.  Has 2 double bonds.


My guess is that 1 requires least and 3 requires most temperature