Standard Enthalpy of Formation vs Standard Enthalpy of Reaction

[Andy Nguyen 1A]

What is the difference between the standard enthalpy of formation and the standard enthalpy of the reaction?

[Jana Sun 1I]

One key piece of information is that the standard enthalpy of formation is the standard enthalpy of reaction for the formation of one mole of a substance. Therefore, the units on a standard enthalpy of formation will always be in KJ/mol.

You can also refer to this previous post addressing the differences: viewtopic.php?t=345!

[Lourick Bustamante 1B]

By definition according to Lavelle, standard enthalpy of a reaction occurs when all reactants and products are in their standard states at 1 ATM. It's also known as reaction enthalpy. Standard enthalpy of formation, on the other hand, is the standard reaction enthalpy for the formation of one mole of a substance from its elements in their most stable form.

[Clara Rehmann 1K]

To add on to what other posters have replied, standard enthalpy of formation requires that reactants must be at their most stable states.