States

[Jenny Tran 2B]

When reactants and products are in different states or not in standard state, how would this change how you would go about finding total change in enthalpy?

[Yanaa_Mehra_1K]

When reactants or products are not in standard state, their enthalpy of formation will not be 0. In this case, the enthalpy of formation of reactants or products will be given. Then we use the 3rd method which is adding the enthalpies of formation of all products and subtracting the enthalpies of formation of reactants from it which will give us the change in enthalpy of the reaction.
Hope this helps.

[Andrew Wang 1K]

When a phase change is included in the reaction, the heat of phase transformation must be included in the enthalpy equation. For example,

Condensation H2O (g) -> H2O (l) takes has a delta H of -40.65 kJ/mol, you would simply included this with all the other enthalpies in the reaction.