branching and combustion values (difficulty 3/10)

[liveoak]

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why would n-butane have a higher heat of combustion than isobutane?

the one with the higher heat of combustion, has less stability.

my thought process was branching = steric strain = weaker bonds.

I guess not. 😡

 

[Pisiform]

The greater the number of Carbon Atoms, the greater would be the heat of combustion due to Vander Waal forces.

Incase of branching, the more the molecule is branched, the more stable it is and so lower heat of combustion.

But, no. of carbon atoms take precedence over branching.

 

[liveoak]

The greater the number of Carbon Atoms, the
Incase of branching, the more the molecule is branched, the more stable it is and so lower heat of combustion.

but why?

But, no. of carbon atoms take precedence over branching.

make sense

 

[loveoforganic]

VDW's might explain the branching effect (too long ago for me to say for sure), but I'm pretty sure the effect due to the number of carbons is due, well, to the number of carbons. There's more carbon and hydrogen in a bigger molecule to be oxidized and release energy from.