Enthalpy Formula

Moderators: Chem_Mod, Chem_Admin

Jasmine 2C
Posts: 184
Joined: Wed Sep 18, 2019 12:18 am

Enthalpy Formula

Postby Jasmine 2C » Sun Feb 09, 2020 6:31 pm

In lecture, we went over 3 methods to calculate enthalpy as well as ΔH = H(products) - H(reactants). In the textbook, they have the formula ΔH = ΔU + PΔV. Are we not allowed to use this formula (alongside ΔU = q + w) to calculate the change in enthalpy?

Posts: 100
Joined: Sat Aug 17, 2019 12:17 am

Re: Enthalpy Formula

Postby Jared_Yuge » Sun Feb 09, 2020 6:42 pm

We can definitely use that equation, cause its just a reworked 1st law equation. Under constant pressure q=delta H and w= -P deltaV

Angela Wu-2H
Posts: 50
Joined: Fri Aug 30, 2019 12:16 am

Re: Enthalpy Formula

Postby Angela Wu-2H » Sun Feb 09, 2020 6:45 pm

The formula is basically derived from each other, so I believe we could use both.

qp=delta H so
delta U = q+w ------> delta U = delta H + w
w = -p*delta V -------> delta U = delta H -p*delta V
solve for delta H so...
delta H = delta U + p*delta V

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

Who is online

Users browsing this forum: Arielle Sass 2A, Heather Costa 2C, Jonathan Batac - 2D and 2 guests