# How do the pressure acting on the reactants and the initial temperature of the reactants affect the enthalpy of reaction?

In an exothermic reaction that occurs under constant pressure, does the pressure acting on the reactants affect the enthalpy of reaction? Does the initial temperature of the reactants affect the enthalpy of reaction? If so, how and why?

The idea of "standard enthalpy of reaction" seems to imply that the pressure acting on the reactants and the initial temperature of the reactants do affect the enthalpy of reaction.

According to Wikipedia,

The standard enthalpy of reaction (denoted $\Delta H_r^{⊖}$) is the enthalpy change that occurs in a system when matter is transformed by a given chemical reaction, when all reactants and products are in their standard states.

"Standard states" means that the reactants are at $\pu{10^5 Pa}$ and $\pu{298.15 K}$, implying that if the reactants are not at their standard states, the enthalpy of reaction will be different.

However, I don't understand why the enthalpy of reaction would change. After all, if the same number of moles of reactants form/break bonds in the same way, shouldn't the heat released be the same, regardless of the pressure and the initial temperature?

EDIT: I recently learned about Le Chatelier's principle, which describes how changes in concentration, temperature, volume, and pressure affect a system in dynamic equilibrium. Is this principle related to my original question? Or am I heading in the wrong direction?