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Chemistry: Hess Cycles

Would anyone be able to explain this to me? I know the correct answer is B, but I have no idea why and can't find any online resources for it.

Which reaction is not used to make a Hess cycle for the following reaction?
C2H4 + H2O --> C2H5OH
A: fH ethanol
B: cH ethene
C: cH hydrogen
D: fH ethene
(edited 1 year ago)
Reply 1
so enthalpy of formation is used to make the product and ethene. enthalpy of combustion is used to calculate formation of H20. so combustion of ethene isnt needed
(edited 1 year ago)
Reply 2
Ohhh, thanks
I hadn't realised that the enthalpy of combustion for hydrogen was also just the enthalpy for formation for H2O
very helpful :smile:

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