The Student Room Group

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 10 months 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 10 months 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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