{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Lecture 21 - Chem 338 Lecture 21 Eyrings Transition State...

Info icon This preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
Chem 338 / ( ) E kT rate k T Ae −Δ ( ) 1 2 2 8 / / ( ) E kT A B rate A B A B m m k T r r kT e m m π −Δ + = + 0 / ( ) ( / ) ( ) ( / ) q V E kT rate q q A B V V k T kT h E e d E kT κ ⎞⎛ ⎟⎜ ⎠⎝ = Chem 338 Lecture 21 Eyring’s Transition State Theory 1. Arrhenius activation energy: 2. Collision theory rate law: 3. Potential energy surface. 4. Eyring’s Transition State Theory: 5. Tunneling: κ ( E )
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
Chem 338 / ( ) E kT rate k T Ae −Δ Eyring’s Transition State Theory 1. Arrhenius Deviation from straight line!
Image of page 2
Chem 338 ( ) 1 2 2 8 / / A B B B A B A B m m dN N Vol r r kT dt m m π π + = + 1 2 8 / / AB AB kT υ πμ = ( ) 1 2 2 8 / / ( ) E kT A B rate A B A B m m T k T r r k e m m π −Δ + = + [ ] ( ) 1 2 2 8 / # / / / A B A B A B A B d col Vol m m N Vol N Vol r r kT dt m m π + = + ⎤ ⎡ ⎦ ⎣ 2. W. C. McC. Lewis: Collision Theory Collision cylinder of length υ AB dt and cross section π ( r A + r B ) 2 . The mean relative velocity υ A B had been calculated 50 years earlier by Maxwell and Boltzmann: so the number of collisions for each A molecule is: and the total rate of collisions per unit volume for all A molecules is: giving the collision theory rate constant:
Image of page 3

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

View Full Document Right Arrow Icon
Chem 338 Collision Theory Wrong deviation from straight line! α ~ 2 ( ) 1 2 2 8 / / ( ) E kT A B rate A B A B m m T k T r r k e m m π −Δ + = +
Image of page 4
Chem 338 3. Potential energy surface.
Image of page 5

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

View Full Document Right Arrow Icon
Chem 338 4. Henry Eyring’s Transition State Theory: Eyring formulated absolute reaction rates " in terms of quantities which are available from potential energy surfaces ". He defined the " activated complex " (we now prefer transition state ) as " a saddle point with positive curvature in all degrees of freedom except the one which corresponds to crossing the barrier [i.e. the reaction path] for which it is of course negative ." He assumed that once the forces between atoms have been treated quantum mechanically, the
Image of page 6
Image of page 7
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