810.2 Mechanism assumption and Approximate treatment 10.2. 1 Approximation treatment of complex reaction mechanism (1)Steady-state approximation (2)Rate-determining step(r d S) approximation For reaction: H+ Br-2 HBr For reaction: d HBr kh,Br 1/2 HBI 2NO,+F→>2NO3F 1+m B The experimental rate equation is: In 1919.. A. Christiansen. K. F r=k[nO,e Herzfeld and m Polanyi independently proposed the mechanism consisting of No+E-k>NOF+F five elementary reactions F+no-k >NOFIn 1919, J. A. Christiansen, K. F. Herzfeld and M. Polanyi independently proposed the mechanism consisting of five elementary reactions: (1) Steady-state approximation For reaction: H2 + Br2 → 2 HBr 1/ 2 2 2 2 [HBr] [H ][Br ] [HBr] 1 Br d k dt m = + 10.2.1 Approximation treatment of complex reaction mechanism (2) Rate-determining step (r. d. s.) approximation 2 2 2 2NO F 2NO F + → For reaction: 2 2 r k = [NO ][F ] The experimental rate equation is: §10.2 Mechanism assumption and Approximate treatment 1 2 2 2 2 2 2 NO +F NO F F F NO NO F k k ⎯⎯→ + + ⎯⎯→