Applications of Hess's Law

Hess’s Law

energy in a reaction system must be conserved, cannot be created or destroyed

-overall enthalpy change for a reaction is equal, regardless of route taken

Hess’s Law triangular circle

enthalpies of formation - arrows point from central product C

enthalpies of combustion - arrows point towards central product (always H₂O + CO₂)

bond enthalpy data is average data representing →

energy required to break one mole of the stated bond in a gaseous state, under standard conditions

overall energy change = arrows always point to central product