Hess's law find entholpy in overall reaction?

Question

The equations given in the problem introduction can be added together to give the following reaction:

overall: .

However, one of them must be reversed. Which one?


The equations given in the problem introduction can be added together to give the following reaction:

overall: .

However, one of them must be reversed. Which one?

The equations given in the problem introduction can be added together to give the following reaction:
C2H4+H2O----C2H5OH
However, one of them must be reversed. Which one?
C2H5OH+3O2---2CO2+3H2O
C2H4+3O2---2CO2+2H2O

Answer 1

The trick is to make sure the reactants and products are on the correct side of the equations. That is how you determine which should be reversed.

In your example the first equation needs to be reversed (and the sign of the enthalpy changed). You have C2H5OH on the reactant side and your final equation needs it on the product side.