hess's law

Moderators: Chem_Mod, Chem_Admin

josmit_1D
Posts: 107
Joined: Fri Aug 09, 2019 12:17 am

hess's law

Postby josmit_1D » Sun Jan 26, 2020 3:21 pm

what does hess's law state?

Kaitlyn Ang 1J
Posts: 116
Joined: Fri Aug 09, 2019 12:17 am
Been upvoted: 1 time

Re: hess's law

Postby Kaitlyn Ang 1J » Sun Jan 26, 2020 3:22 pm

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

Amanda Mei 1B
Posts: 109
Joined: Sat Aug 24, 2019 12:16 am

Re: hess's law

Postby Amanda Mei 1B » Sun Jan 26, 2020 3:49 pm

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
Posts: 101
Joined: Fri Aug 30, 2019 12:18 am

Re: hess's law

Postby Alice Chang 2H » Sun Jan 26, 2020 4:20 pm

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
Posts: 112
Joined: Wed Sep 18, 2019 12:21 am

Re: hess's law

Postby AGaeta_2C » Sun Jan 26, 2020 9:46 pm

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
Posts: 103
Joined: Sat Sep 14, 2019 12:16 am

Re: hess's law

Postby 805422680 » Sun Jan 26, 2020 9:50 pm

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


Return to “Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)”

Who is online

Users browsing this forum: No registered users and 2 guests