How do I assess the enthalpy of a combustion reaction, when MORE than one mole of hydrocarbon is combusted?

Answer 1

Enthalpy change, #DeltaH#, is quoted #"per mole of reaction as written."#

For simple hydrocarbon combustions, e.g.

#CH_4(g) + 2O_2(g) rarr CO_2(g) +2H_2O(g)#, #DeltaH=??#

It is obvious that doubling the quantity of methane burned will result in a doubling of the reaction's energy output. The enthalpy change is expressed per mole of reaction as written.

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Answer 2

Owen Ambrose

You would assess the enthalpy of a combustion reaction for more than one mole of hydrocarbon by multiplying the enthalpy change per mole of the hydrocarbon by the number of moles combusted. This gives you the total enthalpy change for the reaction.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.