Enthalpy as a state function

Because the enthalpy is a thermodynamic property, the value of AH depends only on the nature and state of the initial reactants and final products, and not on the reactions that have been used to carry out the transformation. If we must deal with a reaction whose AH is not available, it is sufficient to find a series of reactions for which AH s are available and whose sum is the reaction in question. 

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The laws of thermodynamics are the cornerstones of any description of a system at equilibrium. The First Law (the energy conservation law) introduces H, the enthalpy, as a state function of a system. State functions depend only on the state of the system and not on how it managed to arrive at that state. 

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