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enthalpy changes of combustion

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blueyedevil | 22:48 Thu 28th Jun 2007 | Science
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I did an experiment on the enthalpy change of combusion of a range of fuels. I am now trying to write it up and keep struggling with my hypothesis - I know I did it in the wrong order.
Anyway, although I know its wrong - or at least can't really be said because I can only know the number of bonds for one atom of the molecule rather than the number of bonds for the amount in the spirit burners - I keep wanting to say that the fuels with more bonds will have a greater enthalpy change.
What could my hypothesis be? Any ideas, or just some simple explaining to a dummy kinda help would be great. Thanks
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Enthalpy change is normally expressed in kilojoules per mole. For example a fuel like ethanol (C2H5OH) has a relative molecular mass of 46 and propan-1-ol (C3H7OH) has a relative molecular mass of 60.
One mole of propan-1-ol (60g) will have a higher enthalpy of combustion than one mole of ethanol (46g) because there are more stronger bonds formed. C-C, C-H and C-O bonds are broken in the alcohol and much stronger bonds are formed during the combustion process ie. C=O bond in carbon dioxide and O-H bond in water.
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thankyou so much teddio, I think I understand it a bit better now. or at least I was able to write a reasonably understandable introduction and hypothesis. Thanks

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