Reversible reaction definition

The definitions of the empirical rate laws given above do not exclude empirical rate laws of another fomi. Examples are reactions, where a reverse reaction is important, such as in the cis-trans isomerization of 1,2-dichloroethene ... 

The term lime also has a broad coimotation and frequently is used in referring to limestone. According to precise definition, lime can only be a burned form quicklime, hydrated lime, or hydraiflic lime. These products are oxides or hydroxides of calcium and magnesium, except hydraiflic types in which the CaO and MgO are chemically combined with impurities. The oxide is converted to a hydroxide by slaking, an exothermic reaction in which the water combines chemically with the lime. These reversible reactions for both high calcium and dolomitic types are Quicklime... 

Equilibrium Potential The minimum potential, which is necessary to perform a (reversible) reaction, is the equilibrium potential E, defined for zero cell current. It is typical for a given reaction. By definition, it is related to the NHE, which represents the potential zero. If the electrode reaction is coupled with the reaction 2 + 2e H2 at the NHE, theoreti-... 

A quasireversible electrode reaction is controlled by the film thickness parameter A, and additionally by the electrode kinetic parameter k. The definition and physical meaning of the latter parameter is the same as for quasireversible reaction under semi-infinite diffusion conditions (Sect. 2.1.2). Like for a reversible reaction, the dimensionless net peak current depends sigmoidally on the logarithm of the thickness parameter. The typical region of restricted diffusion depends slightly on K. For instance, for log( If) = -0.6, the reaction is under restricted diffusion condition within the interval log(A) < 0.2, whereas for log(if) = 0.6, the corresponding interval is log(A) <0.4. 

The use of enzymes to catalyze reversible reactions has proven to be an effective strategy for DCC. Enzymes work under physiological conditions (by definition), are reversible, and can also be applied to a variety of C-C and C-X bond-forming reactions. Venton and coworkers reported the first example of an enzyme-catalyzed process being used in a DCC context [32]. As their work preceded the codification of DCC in the literature, it contains little of the vocabulary that has come to define the field. It does, however, correspond perfectly with the conceptual framework of DCC, and has been widely cited as an influential early example of the DCC idea. 

As can be seen, we do not have much additional information about Reactions 3 and reverse Reactions 3, 4, or 5. The rate constants of these reactions are buried in C, which is independent of TMAE concentration by definition, and appears to be independent of 1-octanol. The experimental data on this latter point were weak since C was difficult to evaluate there is as yet no measure of its temperature dependence. 

Even under fixed outer components concentration, the simple "narrow place" behavior could be spoiled by branching or by reverse reactions. For such reaction systems definition of a limiting step simply as a step with the smallest constant does not work. The simplest example is given by the cycle Aj <-> A2- As Ai. Even if the constant of the last step As- Aj is the smallest one, the stationary rate may be much smaller than ksb (where b is the overall balance of concentrations, b = C1+C2+C3), if the constant of the reverse reaction A2->Ai is sufficiently big. 

Ray (1983) proposed the use of sensitivity analysis. He considered cycles of reversible reactions and suggested a definition The rate-limiting step in a reaction... 

Reversible, definition, 1419 Reversible electrode, definition, 834, 1113 Reversible hydrogen electrode. 815. 1207 Reversible reaction, 1251 Reversible region, 1255 Resistance, 1172 faradaic, 1175 ohmic, 1175... 

Marcus and Rice6 made a more detailed analysis of the recombination from the point of view of the reverse reaction, the unimolecular decomposition of ethane, C2Ha - 2CH3. By the principle of microscopic reversibility the transition states must be the same for forward and reverse paths. Although they reached no definite conclusion they pointed out that a very efficient recombination of CH3 radicals would imply a very high Arrhenius A factor for the unimolecular rate constant of the C2H6 decomposition which in turn would be compatible only with a very "loose transition state. Conversely, a very low recombination efficiency would imply a very tight structure for the transition state and a low A factor for the unimolecular decomposition. 

At the present time a number of gaseous unimolecular reactions are known. The view that none exist, although it appeared plausible for a time, has now been definitely abandoned. Nevertheless, unimolecular reactions are rather exceptional and appear to be confined to molecules of rather complex structure. It is possible that the decomposition of diatomic molecules into atoms at high temperatures is unimolecular but more probable that it is bimolecular, the reverse reaction of recombination being termolecular. Thus the rate of dissociation of chlorine would be k1 [Cl2]2 while the rate of recombination of the atoms would be 2 [Cl]2 [Clg], according to the Herzfeld theory (p. 111). 

The rates of the forward ( f) and reverse (kT) reactions together with the mass transport parameters of the species involved in the transduction mechanism are important for the response of the sensor. Introducing reaction rates into the definition of the equilibrium constant introduces the notion of time. Thus, for the same value of K we can have fast and slow, forward and reverse reactions, and therefore fast or slow equilibrium. The equilibrium constant (K) is expressed in terms of activities. 

By definition, the transition state cannot engage in chemical reactions with other species. It can either pass on to the product state or revert to the reactants, that is, to the products of the reverse reaction. (According to the principle of microscopic reversibility, the forward and reverse of the same reaction must proceed through the same transition state.)... 

The first attempt to establish the mechanisms of the anomerizations was published by Bonner.79 An extensive study was made of the anomerizations of the D-glucopyranose pentaacetates in mixtures of acetic anhydride and acetic acid in the presence of sulfuric acid. The rate of reaction was found to be greatest in pure acetic anhydride. The anomerizations were shown to be inversions specific for the anomeric center. The data did not allow definite conclusions regarding the reaction mechanisms. Nevertheless, a mechanism was proposed, for both the forward and reverse reactions, which appeared the most attractive of those which could be postulated to account for the experimental facts that the anomerization... 

Both Newton s equation of motion for a classical system and Schrodinger s equation for a quantum system are unchanged by time reversal, i.e., when the sign of the time is changed. Due to this symmetry under time reversal, the transition probability for a forward and the reverse reaction is the same, and consequently a definite relationship exists between the cross-sections for forward and reverse reactions. This relationship, based on the reversibility of the equations of motion, is known as the principle of microscopic reversibility, sometimes also referred to as the reciprocity theorem. The statistical relationship between rate constants for forward and reverse reactions at equilibrium is known as the principle of detailed balance, and we will show that this principle is a consequence of microscopic reversibility. These relations are very useful for obtaining information about reverse reactions once the forward rate constants or cross-sections are known. Let us begin with a discussion of microscopic reversibility. 

Although we are very uncertain about the intermediate formation of definite hydroxides we are certain that the water in which the metal oxides is suspended contains metal ions and hydroxide ions, and we can represent the equilibrium condition by the reversible reactions ... 

A fairly exact quantitative relationship exists among the concentrations of all the components of a reversible reaction when this reaction is at equilibrium this is known as the law of molecular concentrations, and may be stated as follows when a reversible reaction has reached a state of equilibrium, the product of the molecular concentrations of all the components on one side of the reaction bears a definite numerical ratio to the product of the molecular concentrations of all the components on the other side of the reaction. This ratio is known as the equilibrium constant of the reaction, and it is always the same at the same temperature although it may have different values at other... 

The correct answer is (C). Bases in this reaction would be considered the substances that are accepting protons (Bronsted-Lowry definition). In the forward reaction, HzO receives a hydrogen to become a hydronium ion. In the reverse reaction, CN receives a proton to become HCN. HCN donates a proton, which makes it an acid. 

Ruthenium Dichloride, RuCL, was stated by Claus4 to result w hen chlorine is passed over heated ruthenium. Repetition of the experiment by Gutbier and Trenkner5 in 1905 led to no definite result, varying amounts of chlorine being absorbed, but always considerably less than theory requires for the dichloride. The experiments w7ere by no means exhaustive, and do not justify the assumption that the dichloride cannot be prepared in this way. As Gutbier points out, it is quite possible that a reversible reaction takes place between the ruthenium and chlorine, thus ... 

As pointed out by Stork and coworkers in their definitive 1963 paper3, the reaction with electrophilic alkenes is especially successful since reaction at nitrogen is reversible. Reaction at the /2-carbon is (usually) rendered irreversible by, in the case of cyclohexanone enamines, internal proton transfer of the axial C-/2 proton to the anionic centre of the initially formed zwitterionic intermediate (34), under conditions of stereoelectronic control (Scheme 22). When this intramolecular proton transfer cannot occur in aprotic solvents, or when the product produced in protic solvents is a stronger carbon acid than adduct 35 (i.e. when Z = COR, N02), then carbon alkylation is also reversible and surprising changes in the regioselectivity of reaction may be observed (vide infra see also Section VI.D and Chapter 26). Cyclobutanes (36) and, in the case of a,/ -unsaturated... 

When two reactions oppose each other, they will eventually reach a point where the amount of product formed is equal to the amount of reactant formed. This situation of an equal give and take is called a state oi equilibrium. Equilibrium is defined as a state of balance between two opposing reactions that are occurring at the same rate. Notice that the definition says nothing about the amounts or concentrations of any reactants or products. The only factors that are equal at equilibrium are the rates of the forward and reverse reactions. 

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