Physical chemistr Reaction Kinetics(2) Xuan Cheng Xiamen University
1 Reaction Kinetics (2) Xuan Cheng Xiamen University Physical Chemistry
Ch ical chemistr Reaction Kinetic Simple order reactions Order reaction Rate Law kA≡ak A→)P k 2k A→>P r=k4[小=[Aek k A→)P [ 1+k[4 LAlok n>2A→>P r=4广 1+[4(n-1kn 2 n-1 (n-DIALk
2 Order Reaction Rate Law t1/2 0 A → P 1 A → P 2 A → P n2 A → P o r = k r = kA 2 r = k A n r = k A k t o A A A e − = A o o k t A A A + = 1 k A ak k A ln 2 [A] o k A 1 A n o n n A k 1 1 ( 1) 2 1 − − − − A o k A 2 A n k t A A A n o n o 1 ( 1) 1 1 = + − − − A A k At o = − Simple Order Reactions Physical Chemistry Reaction Kinetics
Ch ical chemistr Reaction Kinetic Typical Complex reactions (Reversible Opposing A<">C reaction reaction (2) Consecutive reaction (3) Competing arae」 reaction reaction →)D
3 Typical Complex Reactions Physical Chemistry Reversible reaction Consecutive reaction Opposing reaction Competing reaction Parallel reaction A C f k ⎯→ kb A B C k k ⎯⎯1→ ⎯⎯2→ A C k ⎯⎯1→ A D k ⎯⎯2→ (1) (2) (3) Reaction Kinetics
Ch ical chemistr Reaction Kinetic Reversible first-Order reactions aA+bB+…→>eE+fF+ (171) Consider the reverse reaction(opposing reaction) A>C the first order in both forward and back directions rh= kb kfla da nh= kbl
4 Physical Chemistry Reversible First-Order Reactions Consider the reverse reaction (opposing reaction) r k [A] f = f A C f k ⎯→ kb aA+ bB +→ eE + fF + (17.1) the first order in both forward and back directions r k [C] b = b [ ] [ ] r k A dt d A f f f = = − [ ] [ ] r k C dt d A b b b = = Reaction Kinetics
Ch ical chemistr Reaction Kinetic Reversible first-Order reactions d4(44)+/4 kfla+ kbe (1731) △[C]=-[ ]-[Cb=-{41-[ C=Clo +[Alo-[a [4 一kf[4]+k{C+[4-[ kblClo +kblA]o-(k +kb)laj (1732)
5 Physical Chemistry [ ] [ ] [ ] [ ] [ ] k A k C dt d A dt d A dt d A f b f b = − + + = (17.31) [C] = −[A] [C]−[C] o = −[A]−[A] o [C] [C] [A] [A] = o + o − [ ] [ ] [ ] [ ] [ ] k A k C A A dt d A = − f + b o + o − [ ] [ ] ( )[ ] [ ] k C k A k k A dt d A = b o + b o − f + b (17.32) Reversible First-Order Reactions Reaction Kinetics