810.2 Mechanism assumption and Approximate treatment 10.2.1 Approximation treatment of complex reaction mechanism (5) Relation of the three approximate treatments. Reaction:A+B→P dc k[A]-(k1+k2[B])C]=0 A C KLA] Mechanism. +k2[B C+B-2>P dP If the generation rate of c is much less than K,CB k,k2LAJB its depletion rate(i.e,, active species) k+h2B k[A]<<k,[C]+k2[BIC When k>>k2 Bl, i.e,k[C]>>k2[Cl most C undergoes reverse reaction so that stationary-state approximation equilibrium can attain rapidly A]>[C kk,AB kAb k<<k1+k2[B Reaction l is a rapid equilibrium.(5) Relation of the three approximate treatments. Reaction: A + B → P Mechanism: If the generation rate of C is much less than its depletion rate (i.e., active species): 1 1 2 k k k [A] [C] [B][C]  + − [A] [C]  1 1 2 k k k [B]  + − stationary-state approximation 10.2.1 Approximation treatment of complex reaction mechanism 1 1 2 [ ] [A] ( [B])[C] 0 d C k k k dt = − + = − 1 ss 1 2 [A] [ ] [B] k C k k − = + 1 2 2 1 2 [A][B] [C][B] [B] dP k k r k dt k k − = = = + When k-1 >> k2 [B], i.e., k-1 [C] >> k2 [B][C], most C undergoes reverse reaction so that equilibrium can attain rapidly. 1 2 1 [A][B] [A][B] k k r k k− = = Reaction 1 is a rapid equilibrium. §10.2 Mechanism assumption and Approximate treatment