物理化学厦门大学共64页
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An overall reaction is a reaction combined with a series of elementary reactions
For examples： H2C2l2HCl
2020/6/13
2011 Physical Chemistry Xiamen University
rate law
(1) C2l M2Cl M k1[C2l][M]
(2) ClH2 HClH k2[Cl][H2]
(3) HC2l HClCl (4) 2Cl MC2l M
k3[H][C2]l k4[Cl2][M]
2020/6/13
2011 Physical Chemistry Xiamen University
t =t [A]0 – x [B]0 + x
t =te [A]0 – xe [B]0 + xe
Differential equation
d[A]k1[A]k-1[B] dt
[A]0+[B]0=[A]+[B]=[A]e+[B]e k1/k -1 =[B]e/[A]e
[B] = [A]e+ [A]ek1/k -1－[A]
k1
AB
k-1
Parallel reactions 平行反应
k1 B
A
k2 C
k3 D
Consecutive reaction 连续反应
A k1 B k2 C
2020/6/13
2011 Physical Chemistry Xiamen University
Reversible (Opposing) Reactions
kf
AB
kb
kf
A+B C
kb
kf
A ຫໍສະໝຸດ Baidu+C
kb
2020/6/13
2011 Physical Chemistry Xiamen University
Reversible First-Order Reactions: Differential equation
k1
AB
t =0
[A]0 k-1 [B]0
Molecularity of Elementary Reaction
The molecularity of an elementary reaction is the number of molecules coming together to react in an elementary reaction.
Law of Mass Action
For an elementary reaction, the rate is proportional to the concentration of of the reactant molecules that meet together.
Elementary reaction
More common situation is that the forward and the back reactions may not be elementary reactions, and may be first-, second- or third-order reactions
For examples
2020/6/13
2011 Physical Chemistry Xiamen University
Typical Combinations of Elementary Reactions
Reversible (Opposing) reactions 对峙反应
k1
AB
k-1
Parallel reactions 平行反应
8.7 Elementary & Complex Reactions
Focuses
I. Concepts
Elementary reactions Overall reactions
基元反应
总包反应
Molecularity 分子数
Reaction order 反应级数
Reaction
mechanism 反应机理
k1 B
A
k2 C
k3 D
Consecutive reaction 连续反应
A k1 B k2 C
2020/6/13
2011 Physical Chemistry Xiamen University
II. Kinetics of typical complex reactions
Reversible (Opposing) reactions 对峙反应
Reaction Mechanism
For an overall reaction, the combination of a series of elementary-reaction steps is the reaction mechanism.
同一反应在不同的条件下，可有不同的反应机理。 了解反应机理可以掌握反应的内在规律，从而更好的 驾驭反应。一个反应机理需要经得起实验和理论的考 验，有时需要作长期的大量的动力学研究。
An elementary reaction refers to a single-step reaction involving a small number of molecules or ions.
For examples： Cl 2 M 2Cl M Cl H 2 HCl H H Cl 2 HCl Cl 2Cl M Cl 2 M
II. Kinetics of typical complex reactions III. Steady-State Approximation IV. Pre-equilibria
2020/6/13
2011 Physical Chemistry Xiamen University
I. Elementary Reactions & Overall Reactions
Elementary reaction
Molecularity
A P
Unimolecular reaction 单分子反应
AB P
Bimolecular reaction 双分子反应
2A B P
Trimolecular reaction 三分子反应
2020/6/13
2011 Physical Chemistry Xiamen University
For examples： H2C2l2HCl
2020/6/13
2011 Physical Chemistry Xiamen University
rate law
(1) C2l M2Cl M k1[C2l][M]
(2) ClH2 HClH k2[Cl][H2]
(3) HC2l HClCl (4) 2Cl MC2l M
k3[H][C2]l k4[Cl2][M]
2020/6/13
2011 Physical Chemistry Xiamen University
t =t [A]0 – x [B]0 + x
t =te [A]0 – xe [B]0 + xe
Differential equation
d[A]k1[A]k-1[B] dt
[A]0+[B]0=[A]+[B]=[A]e+[B]e k1/k -1 =[B]e/[A]e
[B] = [A]e+ [A]ek1/k -1－[A]
k1
AB
k-1
Parallel reactions 平行反应
k1 B
A
k2 C
k3 D
Consecutive reaction 连续反应
A k1 B k2 C
2020/6/13
2011 Physical Chemistry Xiamen University
Reversible (Opposing) Reactions
kf
AB
kb
kf
A+B C
kb
kf
A ຫໍສະໝຸດ Baidu+C
kb
2020/6/13
2011 Physical Chemistry Xiamen University
Reversible First-Order Reactions: Differential equation
k1
AB
t =0
[A]0 k-1 [B]0
Molecularity of Elementary Reaction
The molecularity of an elementary reaction is the number of molecules coming together to react in an elementary reaction.
Law of Mass Action
For an elementary reaction, the rate is proportional to the concentration of of the reactant molecules that meet together.
Elementary reaction
More common situation is that the forward and the back reactions may not be elementary reactions, and may be first-, second- or third-order reactions
For examples
2020/6/13
2011 Physical Chemistry Xiamen University
Typical Combinations of Elementary Reactions
Reversible (Opposing) reactions 对峙反应
k1
AB
k-1
Parallel reactions 平行反应
8.7 Elementary & Complex Reactions
Focuses
I. Concepts
Elementary reactions Overall reactions
基元反应
总包反应
Molecularity 分子数
Reaction order 反应级数
Reaction
mechanism 反应机理
k1 B
A
k2 C
k3 D
Consecutive reaction 连续反应
A k1 B k2 C
2020/6/13
2011 Physical Chemistry Xiamen University
II. Kinetics of typical complex reactions
Reversible (Opposing) reactions 对峙反应
Reaction Mechanism
For an overall reaction, the combination of a series of elementary-reaction steps is the reaction mechanism.
同一反应在不同的条件下，可有不同的反应机理。 了解反应机理可以掌握反应的内在规律，从而更好的 驾驭反应。一个反应机理需要经得起实验和理论的考 验，有时需要作长期的大量的动力学研究。
An elementary reaction refers to a single-step reaction involving a small number of molecules or ions.
For examples： Cl 2 M 2Cl M Cl H 2 HCl H H Cl 2 HCl Cl 2Cl M Cl 2 M
II. Kinetics of typical complex reactions III. Steady-State Approximation IV. Pre-equilibria
2020/6/13
2011 Physical Chemistry Xiamen University
I. Elementary Reactions & Overall Reactions
Elementary reaction
Molecularity
A P
Unimolecular reaction 单分子反应
AB P
Bimolecular reaction 双分子反应
2A B P
Trimolecular reaction 三分子反应
2020/6/13
2011 Physical Chemistry Xiamen University