物理化学.厦门大学.ppt

2016-12-27 2011 Physical Chemistry Xiamen University C hapter 8 Chemical ics-2 Elementary plex reactions Reaction ics and equilibrium state u Speculation of reaction mechanism u Activation energy for plex reactions 2016-12-27 2011 Physical Chemistry Xiamen University Elementary & Complex Reactions Focuses Focuses Elementary reactions 基元反应 Molecularity 分子数 Overall reactions 总包反应 Reaction order 反应级数 Reaction mechanism 反应机理 I. Concepts II. ics of plex reactions III. Steady-State Approximation IV. Pre- equilibria 2016-12-27 2011 Physical Chemistry Xiamen University I. Elementary Reactions & Overall Reactions An elementary reaction refers to a single-step reaction involving a small number of molecules or ions. M Cl M 2Cl Cl HCl Cl H H HCl H Cl M 2Cl M Cl 2 2 2 2???????????? For examples : An overall reaction is a bined with a series of elementary reactions For examples : HCl 2 Cl H 22?? 2016-12-27 2011 Physical Chemistry Xiamen University Molecularity of Elementary Reaction The molecularity of an elementary reaction is the number of ing together to react in an elementary reaction. PA??? Elementary reaction Unimolecular reaction 单分子反应 Molecularity Bimolecular reaction 双分子反应 Trimolecular reaction 三分子反应 PBA????PB2A???? 2016-12-27 2011 Physical Chemistry Xiamen University Law of Mass Action ]M[ [Cl] M Cl M 2Cl (4) ] [H][Cl Cl HCl Cl H (3) ] Cl][H [H HCl H Cl (2) ][M] [Cl M 2Cl M Cl (1)24 2 2 3 2 2 2 2 21 2k k k k ???????????? rate law Elementary reaction For an elementary reaction, the rate is proportional to the concentration of of the reactant molecules that meet together. 2016-12-27 2011 Physical Chemistry Xiamen University Reaction Mechanism For an overall reaction, bination 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。