Question

What happen to enthalphy when the reaction is reversed?

Answer 1

Hey.

In a reverse reaction the sign changes. That is because Enthalpy is a state function, one that depends on only the current state of the function. That means the energy required to push a reaction to its products would be directly reversed to push it back to its reactants.

The reverse reaction would simply be doing the opposite, meaning that the magnitude would be the same, but the sign would be opposite.


A key use of this knowledge is in Hess's law, and Born Haber Cycle.

Thanks.