1 / 16

Review

. . Review. Reaction mechanism. . C 5 H 11 Br (l). + HBr (l). Br 2 (l). + C 5 H 12 (l). h . 2 Br. step 1. Br 2. C 5 H 12 . step 2. Br . +. HBr + C 5 H 11. C 5 H 11 . +. Br . . C 5 H 11 Br. step 3. overall. Br 2. . C 5 H 11 Br. + HBr. + C 5 H 12. . .

matsu
Download Presentation

Review

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1.  Review Reaction mechanism  C5H11Br(l) + HBr(l) Br2(l) + C5H12(l) h 2 Br. step 1 Br2 C5H12 step 2 Br. + HBr + C5H11. C5H11. + Br.  C5H11Br step 3 overall Br2  C5H11Br + HBr + C5H12

  2.  Br2(l) + C5H12(l) C5H11Br(l) + HBr(l) h 2 Br. step 1 Br2 C5H12 step 2 Br. + HBr + C5H11.  step 3 C5H11. + Br. C5H11Br assumestep 2 is rate determining (slow) rate = k2 [Br.] [C5H12] Br.= intermediate [Br.]2 [Br2] Keq = rate = k2 k’[Br2]1/2 [C5H12] rate = k’[Br2]1/2 [C5H12] [Br.] = Keq1/2 [Br2]1/2 11/2 order reaction

  3. bimolecular elementary steps increase [react]  increase rate of reaction increase T  increase rate of reaction increase number of collisions increase force of collisions

  4. T2 Ea T1 T2 > T1 # molecules Kinetic Energy minimum energy required for reaction: activation energy = Ea

  5. Arrhenius Equation T dependence of a rate constant, k k = z p e-Ea/RT k a) increases b) decreases with T with Ea k a) decreases b) increases Ea = activation energy (kJ/mol) R = gas constant (8.314 x 10-3kJ/K mol) T = temperature (K) z = collision frequency p = steric factor (<1)

  6. p = steric factor z = collision frequency combine to give A A k = e-Ea/RT

  7. Arrhenius Equation k = A e-Ea/RT - (Ea/R) (1/T) ln k = - (Ea/R) (1/T) + ln A ln A y = m x + b plot ln k v.s. 1/T slope = -Ea/R intercept = ln A - 1/T2) ln (k2/ k1) = (Ea /R) (1/T1

  8. A-B + C A...B...C activated complex P.E. is at a maximum transition state A + B-C

  9. activated complex Eaf Eab reactants P.E. Hrxn products Reaction coordinate A-B + C A...B...C A + B-C

  10. activated complex Eaf Eab reactants P.E. Hrxn products Reaction coordinate exothermic Eab Eaf > endothermic

  11. Eab Eaf reactants products activated complex P.E. Reaction coordinate exothermic Eab Eaf > large Ea = slow rate endothermic Eab Eaf <

  12. - catalyst + catalyst lowers Eaf faster forward reaction ( kf ) lowers Ear faster reverse reaction ( kr ) kf and H Keq unchanged Keq = kr

  13. Br2 + C5H12 P.E. C5H11Br + HBr Reaction coordinate Br2(l) + C5H12(l) C5H11Br(l) + HBr(l) Hrxn < 0 Ea Hrxn

  14. hn 2 Br. h step 1 Br2 C5H12 step 2 Br. + HBr + C5H11. step 3 C5H11. + Br.  C5H11Br Br2(l) + C5H12(l) C5H11Br(l) + HBr(l) Ea Ea Ea HBr + C5H11. + Br. 2Br. + C5H12 C5H12 + Br2 P.E. C5H11Br + HBr

More Related