{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

lecture 07 2010 - 36 The Gibbs Free Energy We have seen...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
36 The Gibbs Free Energy We have seen that the entropy, S, is a thermodynamic function of state that allows us to predict when a process is spontaneous or not. The entropy was invented as a variable that allows us to make this determination. Δ S universe = Δ S system + Δ S surroundings 0 If Δ S universe > 0, then the process is spontaneous If Δ S universe = 0, the system is at equilibrium If Δ S universe < 0, then the reverse process is spontaneous Now, knowing what is going on in the entire universe is often not a particularly useful way to determine spontaneity. It would be better to have a function that can be evaluated more simply and depend only on the system. The appropriate variable is the Gibbs Free Energy , denoted G, and is appropriate for constant temperature and pressure situations . G = H – TS defines the Gibbs free energy. At constant temperature, Δ G = Δ H - T Δ S defines the change in Gibbs Free energy. Note that this definition is consistent with Δ G = q P – q rev = q actual – q rev Recall that if q actual is q rev , then Δ G = 0.
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern