Introduced to this in AP Chemistry
What is it
When reactants are converted to products, the change in enthalpy is the same whether the reaction takes place in one step or in a series of steps.
In simpler terms: The enthalpy change is the same either way if you take 1 step or multiple steps
State function: Doesn’t matter how you get there only where you start and end
Example
If the reaction is an endothermic reaction then the reverse reaction is always an exothermic reaction
Refer to Enthalpy for Endothermic and Exothermic reactions