Understanding Hess' Law: C2H4 + H2O -> C2H5OH

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The discussion centers on calculating the enthalpy change for the reaction C2H4 + H2O -> C2H5OH using Hess' Law. The user initially calculates the total ΔH as -89 kJ by summing the enthalpy changes of the reactions. However, the textbook states the correct answer is +3 kJ, leading to confusion. The discrepancy arises from a misunderstanding of how to apply Hess' Law correctly in this context. Clarification on the proper application of Hess' Law is necessary to resolve the conflicting results.
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Homework Statement


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Homework Equations



Hess' Law

The Attempt at a Solution



C2H4 (g) + H2O (g) -> C2H5OH (g) ΔH = - 46 kJ
C2H5OH(g) -> C2H5OH(l) ΔH = - 43 kJI think the ΔH is - 46 - 43 = - 89

However, the book says that the answer is A. +3 kJ
How come that be?
 
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It can't be, that's how. Your answer is right.
 
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