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Topic: Lenghts of hydrocarbons  (Read 2361 times)

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Offline kapital

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Lenghts of hydrocarbons
« on: December 26, 2015, 09:32:35 AM »
Why does stability of hydrocarbons decreases when the length is 20 carbons and more? Thanx for answers?

Offline Enthalpy

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Re: Lenghts of hydrocarbons
« Reply #1 on: December 27, 2015, 06:04:16 PM »
I don't understand. What do you call stability: resistance to thermal decomposition, heat of formation...?

Offline kapital

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Re: Lenghts of hydrocarbons
« Reply #2 on: December 28, 2015, 04:39:33 PM »
Mostly let say the ability to not decompose over room temperature

Offline Enthalpy

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Re: Lenghts of hydrocarbons
« Reply #3 on: December 28, 2015, 05:53:49 PM »
I don't know the answer for sure. Longer alkanes also show a lower autoignition temperature. I believe this is not linked with bond strength nor electron affinity and the like. Some possibilities:

Longer alkanes have more vibration modes and this permits to concentrate more heat on a given atom or bond.

Too short alkanes need a higher temperature to excite the vibration modes.

Longer alkanes have more possibilities to deform into cycles and make aromatic compounds.

I too would be interested in models, interpretations, explanations.

Offline orgopete

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Re: Lenghts of hydrocarbons
« Reply #4 on: December 31, 2015, 07:40:04 AM »
Why does stability of hydrocarbons decreases when the length is 20 carbons and more? Thanx for answers?

What data are you referring to? Can you post it?
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