hess's law

[josmit_1D]

what does hess's law state?

[Kaitlyn Ang 1J]

Because enthalpy is a state function, meaning it depends on the physical state of the molecule, enthalpy changes are additive.

[Amanda Mei 1B]

Hess's Law states that enthalpy is a state function, so its value is determined by its current state, not the path taken to obtain that state. Thus, the total enthalpy change of a multi-step reaction can be calculated by adding the enthalpy change at each step of the reaction.

[Alice Chang 2H]

https://www.khanacademy.org/science/chemistry/thermodynamics-chemistry/enthalpy-chemistry-sal/v/hess-s-law-example

I'm not sure if this will help clarify things, but this is a worked example from Khan Academy using Hess's Law if you learn more visually.

[AGaeta_2C]

It states that because enthalpy is a state property, changes in enthalpy are additive. in other words, enthalpy change in each step of a multistep rxn can be added to give TOTAL enthalpy change.

[805422680]

the total enthalpy of the system remains the same regardless of the route taken to reach the final product. this is important when the reaction from reactants to products in one step is energetically or chemically unfavorable