I am currently working on an investigation where I am burning isomers of butanol to test for the heat of combustion values to see which fuel is most efficient. The fuels I am testing are 1-butanol, 2-butanol, 2-methylpropan-1-ol (isobutanol) and 2-methylpopan-2-ol (tert-butyl alcohol).
I have researched that the heat of combustion values for these fuels are as follows:
- 1-butanol: −2671 kJ/mol
- 2-butanol: −2661.1 kJ/mol
- Isobutanol: −2662.6 kJ/mol
- Tert-butyl alcohol: −2644.8 kJ/mol
So evidently, my experimental results should also show similarity in the ordering of greatest to lowest heat of combustion values.
However, I am wondering why isomers of butanol have different heat of combustions. I know it has to do with the shape of the molecules and whatnot, but how does this affect the energy released? What about bond angles?