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Published byMorgan Johnston Modified over 9 years ago
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Detail study on a chemical reaction 1)Stoichiometric: balance of the equation reactants; products; ratio. 3) Kinetic: Rate and mechanism rate; catalyst; rate constant; mechanism; selectivity. 2) Thermodynamic: Spontaneity and equilibrium direction; equilibrium; yields.
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Brief history of chemical kinetics (1)1850s-1910s: Empirical kinetics (2)1910s-1950s: Elementary reactions; (3)1950s-present: Microscopic kinetics: molecular dynamics, state-to-state dynamics Chemical kinetics: A branch of chemistry that concerns reaction rate and mechanism.
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Main concerns of chemical kinetics: 1) Reaction rate: factors that determines the rate of reaction, rate law. 2) Reaction mechanism: the series of steps by which a reaction takes place. 3) structure-dependence of reactivity: the correlation between molecular structure and reaction potential.
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§ 9.1 Introduction of chemical kinetics ----- concepts and terms Scientific language: Each science has its own language: Word: concepts, terms; Grammar: nomenclature, rule, law
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H 2 + I 2 = 2 HI 1) I 2 = 2I 2) 2I + H 2 = 2HI H 2 + Br 2 = 2 HBr 1) Br 2 = 2 Br 2) Br + H 2 = HBr + H 3) H + Br 2 = HBr + Br 4) H + HBr = H 2 + Br 5) 2 Br = Br 2 Reaction mechanism/pathway: the detailed way by which the reactants are converted into products, or the series of steps by which a reaction takes place. Reaction mechanism / reaction pathway multistep reaction Elementary reaction: the reaction that completes in one act Intermediate: the species formed in one step and consumed in a subsequent step and never seen as a product The sum of the elementary reactions and their series.
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1) elementary reactions According to the number of molecules involved in the reaction, elementary reactions can be divided into three kinds: unimolecular reaction: (decomposition, isomerization) I 2 = 2I bimolecular reaction: (combination) Br + H 2 = HBr + H termolecular reaction: 2I + H 2 = 2HI
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According to the number of elementary reactions involved, the overall reaction can be classified into: 2) overall reactions Ethylene butadiene cyclohexene simple reaction Diels-Alder addition: complex reaction Overall reaction
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Hydrolysis of nitrile Find differences between mechanisms described in physical chemistry and those in organic chemistry.
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Levine p. 528-529 17.1 reaction kinetics rate of reaction, rate laws, reaction mechanism 17.2 measurement of reaction rates 17.3 integration of rate law first-order reactions; second-order reactions; third-order reactions zero-order reaction; n-th-order reaction
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