8 10.2 Approximate treatment of rate equation and mechanism assumption Extensive reacting: Levine: p545 17.6
§10.2 Approximate treatment of rate equation and mechanism assumption Extensive reacting: Levine: p.545 17.6
Summary k k k x Re A b K (k+k_)t=kt k C X -x (x。-x) K1 B dx yK =k(a-x)+k(-x)=(k+k2)a-x) A ∠ 0 A-4>B->C kk dt k2-K, lexp(kt)-exp(-k2t)
A B C 1 2 ⎯⎯→ ⎯⎯→ k k − + = k k Kc e e e ln ( ) x x k at x x + = − e e ln ( ) ( ) x k k t kt x x = + = + − − ( ) ( ) ( )( ) 1 2 1 2 k a x k a x k k a x dt dx = − + − = + − 2 1 k k z y = = 0 dt dy 1 2 1 2 2 1 dc ak k Z exp( k t ) exp( k t ) dt k k = − − − − Summary
810.2 Mechanism assumption and Approximate treatment 10.2.1 Approximation treatment of complex reaction mechanism Necessary of approximation treatment 1)Br2->2Br AA>B—kC 2)Br·+H,—>HBr+H k, 3)正.+Br2->HBr+Br exp(k,)-exp(] k-k A4)H+HBr→→H2+Br 5)2Br·—>Br2 k exp(k,t) k2-k1 dhAr ? k1 exp(kt) k2-k1
Necessary of approximation treatment 10.2.1 Approximation treatment of complex reaction mechanism A B C 1 2 ⎯⎯→ ⎯⎯→ k k exp( ) exp( ) 1 2 2 1 1 k t k t k k k a y − − − − = − − + − − − = exp( ) 1 exp( ) 2 2 1 1 1 2 1 2 k t k k k k t k k k z a 1) Br2 ⎯→ 2Br 2) Br + H2 ⎯→ HBr + H 3) H + Br2 ⎯→ HBr + Br 4) H + HBr ⎯→ H2 + Br 5) 2Br ⎯→ Br2 d[HBr] ? dt = §10.2 Mechanism assumption and Approximate treatment
810.2 Mechanism assumption and Approximate treatment 10.2.1 Approximation treatment of complex reaction mechanism Br.>2Bro To certify the correctness of a proposed Br,+H、kHBr+H mechanism. the mechanism must undergo strict H+Br2→HBr+Br examination H+hbr- kA >h+Br. Whether or not the rate equation derived from aBro BI the proposed mechanism is consistent to the dhAr experimental one is an important criterion However, because of the complexity of the mechanism. the exact treatment of the mechanism k H2IBr is usually impossible and some approximation have 1+k THBr to be introduced
To certify the correctness of a proposed mechanism, the mechanism must undergo strict examination. Whether or not the rate equation derived from the proposed mechanism is consistent to the experimental one is an important criterion. However, because of the complexity of the mechanism, the exact treatment of the mechanism is usually impossible and some approximation have to be introduced. 10.2.1 Approximation treatment of complex reaction mechanism §10.2 Mechanism assumption and Approximate treatment 0.5 2 2 2 [H ][Br ] [HBr] 1 ' [Br ] r k k = + d[HBr] ? dt = 1 2 3 4 5 2 2 2 2 2 Br 2Br Br H HBr H H Br HBr Br H HBr H +Br 2Br Br k k k k k ⎯⎯→ + ⎯⎯→ + + ⎯⎯→ + + ⎯⎯→ ⎯⎯→
810.2 Mechanism assumption and Approximate treatment 10.2.1 Approximation treatment of complex reaction mechanism ZEITSCHRIFT FUR ELEKTROCHEMIE (Bd. 19, 1913 Herr Prof. Dr. M. Bodenstein- Hannover PHOTOCHEMISCHE KINETIK DES CHLORKNALLGASES Max bodenstein was the first man to demonstrate that, in the reaction of hydrogen with chlorine, the high performance could be explained by means of a chain reaction In his kinetic studies he used the quasi-steady state approximation to derive the rate equation of the Max Ernst august bodenstein reactior German physical chemist
Max Bodenstein was the first man to demonstrate that, in the reaction of hydrogen with chlorine, the high performance could be explained by means of a chain reaction. In his kinetic studies, he used the quasi-steady state approximation to derive the rate equation of the reaction. Max Ernst August Bodenstein German physical chemist 10.2.1 Approximation treatment of complex reaction mechanism §10.2 Mechanism assumption and Approximate treatment