Reaction second order

Zero-order reaction First-order reaction Second-order reaction Rate constant... 

Thus, under equimolar conditions, if a plot of 1/[A] against t is linear, the reaction is second order with a slope of k. It is obvious that the same will hold true for a reaction second order in A. ... 

Write a rate law equation for each of the following (a) A reaction first order with respect to A and second order with respect to B. (b) A reaction zero order with respect to A and second order with respect to B. (c) A reaction first order with respect to A and first order with respect to B. (d) A reaction second order with respect to B, its only reactant. 

An impressive body of evidence supports these generalizations. This evidence has been reviewed (Romsted, 1984) and it does not seem necessary to discuss it in detail here, but some examples will be given and some exceptions to these generalizations will be mentioned. Some reactions of OH- are shown in Table 3 for both inert and reactive ion surfactants, and Table 4 gives data for reactions of other hydrophilic ions. Reactions of hydrophobic nucleophiles are shown in Table 2. For all these reactions second-order rate constants in the micellar pseudophase are compared with those in water. For some reactions we also give values of krcl, i.e. the rate constant relative to that in water. These values depend upon the reactant concentration and are included merely to provide an indication of the micellar rate effects. Other examples of micellar rate effects are given in the Appendix. 

The oxidation of nitric oxide, NO(A) + 02 - NO2, is a third-order gas-phase reaction (second-order with respect to NO). Data of Ashmore et al. (1962) for values of the rate constant at various temperatures are as follows ... 

If the forward reaction is pseudo first order and the reverse reaction second order, then, as discussed in Sections 1.4.4 and 1.4.5 in Volume 3, the rate equation may be written as ... 

Firsl Order Reaction Second Order Recet ion... 

That is, the data suggest that Eqs. (101)—(104) should be modified to allow formation of Fby a reaction second order in A, first order in B, and half-order in the catalyst concentration C. The disappearance of F appears to be first order in A and in B. 

This reaction proceeds via the transition state illustrated in Fig. 10.2. An Sn2 reaction (second order nucleophilic substitution) in the rate limiting step involves the attack of the nucleophilic reagent on the rear of the (usually carbon) atom to which the leaving group is attached. The rate is thus proportional to both the concentration of nucleophile and substrate and is therefore second order. On the other hand, in an SnI reaction the rate limiting step ordinarily involves the first order formation of an active intermediate (a carbonium ion or partial carbonium ion, for example,) followed by a much more rapid conversion to product. A sampling of a and 3 2° deuterium isotope effects on some SnI and Sn2 solvolysis reactions (i.e. a reaction between the substrate and the solvent medium) is shown in Table 10.2. The... 

The solvent affects the chemical equilibria of reactions. Second-order rate constants and equilibrium constants have been determined for the benzoate ion promoted deprotonation reactions of (m-nitrophenyl)nitromethane, (p-nitrophenyl)nitromethane, and (3,5-dinitrophenyl)nitromethane in methanol solution. The pKa values for the arylnitromethanes in methanol are the following pKa = 10.9, 10.5, and 9.86 for m-nitrophenyl)nitromethane, (p-nitrophenyl)nitromethane, and (3,5-dinitrophenyl)nitro-methane, respectively, relative to benzoic acid (pKa = 9.4). A Bronsted B value of... 

The reaction of ferricyanide with the semiquinone forms of flavodoxins is more rapid than is the oxygen reaction. Second-order rate constants with A. vinelandii, C. pasteurianum and D. vulgaris flavodoxins are 8.3 x 10 M" s , 1.1 x 10 " s", and 8.3 x lO M s" respectively This is to be compared with a value of... 

As with homogeneous aldol reactions, simple power-type rate equations have been frequently used to describe the kinetics of solid-catalysed condensations. For several liquid phase reactions, second-order kinetics was established, viz. 

Their results are shown in Figure 8-4. All the relationships are obeyed and ki3 was deduced to be 0.017 A/-1 sec-1 at room temperature. It is clear from eq. (f) that when RNO removal is due mainly to reaction (13), then 4>(N2) and, consequently, the NOa yield are proportional to the first power of [NO], even though N2 is produced in a reaction second order in [NO]. 

A more detailed LSV study [58, 89] resulted in the conclusion that the kinetics, under all conditions, could not be described by the simple eCej, scheme. It was proposed that the reaction order in anthracene anion radical (AN- ) varies between 1 and 2 and the reaction order in phenol is greater than 1. A complex mechanism was also indicated from DCV measurements [89]. At a phenol concentration of 10 mM, values of dEpj d log v were in all cases close to that expected for a reaction second order in An-, i.e. 19.5mV decade-1 under the conditions of the experiments. The process is fast enough under these conditions for it to be expected to fall well within the KP zone. That this is the case was indicated by the fact that d p/dlog v was linear over a reasonably wide range of v (10— 1000 mV s-1). The highest value of the slope, observed at a phenol concentration of 100mM, was still significantly lower than 29.3 mV decade -1 predicted for a pseudo-first-order reaction. 

Recently, Pankov and Morgan (1981a,b) emphasized the importance of various mechanisms for regulating kinetics in the aquatic environment. Examples showed the wide range of first- and second order rate constants (kf) and half lifes (ti) for different reactions that might take place in natural waters. The rate constants for several first order trace metal hydrolysis reactions, second order redox- and complexation reactions of interest for aquatic studies are summarized by Hoffmann (1981). His comparison of kinetic data on the oxidation of HS- under only slightly different conditions shows considerable variations e.g., t ranges from 7 -600 min for seawater media. 

Dihydro- nicotin- Enzymatic Reaction Model Reaction Second-Order Rate Constant k... 

Shi Z, Boyd RJ, Intrinsic barriers of some model SN2 reactions second-order Moeller-Plesset perturbation calculations, J Am Chem Soc, 113, 2434-2439 (1991) and refs therein... 

Equation 8.12, more general for reactions second order in aldehyde, can be rearranged ... 

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