Activity physical meaning

The second effect is that of a change in the potentiaf difference effectively influencing the reaction rate. By its physical meaning, the activation energy should not be influenced by the full Galvani potential across the interface but only by the potential difference (cpo ) between the electrode and the reaction zone. Since the Galvani potential is one of the constituent parts of electrode potential E, the difference - j/ should be contained instead of E in Eq. (14.13) ... 

Equation (28) gives the physical meaning of the activation factor H as the free energy required for the system to reach the transitional configuration. 

Containment also brings connotations of employing active and perhaps physical means of preventing escape as in the terms container or containment facility . This term might be most suitably used in the context of bioreactor facilities or self-contained, indoor research and development facilities. 

Normal Operating Conditions (NOC). Under this condition the biomass remains active and the sludge stability is preserved, i.e., Ai, A2 > 0 for alH > 0. This physically means that part of the pollutant agents entering to the digester are consumed by the bacterial culture (i.e., (Ai — Si in) 0 and S2 - S2,in) 7 0). 

Therefore, the physical meaning of the solubility curve of a surfactant is different from that of ordinary substances. Above the critical micelle concentration the thermodynamic functions, for example, the partial molar free energy, the activity, the enthalpy, remain more or less constant. For that reason, micelle formation can be considered as the formation of a new phase. Therefore, the Krafft Point depends on a complicated three phase equilibrium. 

What is the physical meaning of the rate constant of a chemical reaction What is the dimension of the rate constant of a first-(second-) order chemical reaction How does the rate constant depend on the temperature Write the Arrhenius equation. What is called the activation energy What substances are called catalysts and inhibitors ... 

It can be shown that Km equals the concentration of the substrate at which the reaction velocity is one half of its maximum. The Michaelis-Menten constant is an important figure of merit for the enzyme. It is the measure of its activity. Although it describes a kinetic process, it has the physical meaning of dissociation constant, that is, a reciprocal binding constant. It means that the smaller the Km is, the more strongly the substrate binds to the enzyme. 

These interactions exist in real systems for which the activity has the physical meaning of the effective concentration. Thus, only for dilute real solutions does A = a. In mixtures, the activity coefficient is usually, but not always, less than one and is affected by all the species in the multicomponent mixture. 

With few exceptions, enantiomers cannot be separated through physical means. When in racemic mixtures, they have the same physical properties. Enantiomers have similar cliemi cal properties as well. The only chemical difference between a pair of enantiomers occurs in reactions with other chiral compounds. Thus resolution of a racemic mixture typically takes place through a reaction with another optically active reagent. Since living organisms usually produce only one of two possible enantiomers, many optically active reagents can be obtained from natural sources. For instance muscle tissue and (S)-<-)-2-methyl-l-butanol, from yeast fermentation. 

When the isoconversional method is applied to the set of dynamic runs, an activation energy lying in the 69-73 kJ mol-1 range is obtained, without any definite trend with conversion. The value is very close to the one reported by Montserrat and Malek (1993) using this method again, this is an apparent value without any physical meaning. 

We use quotations for the words complex "concentration , "form , and "consume since they have no direct physical meaning. The use, by analogy with the Horn Jackson concept of a "complex could be attempted of a term "activated complex from the theory of absolute rates, but after some speculation we decided that this analogy would not be very reasonable. Values of gj can be interpreted if they are associated with the rates of concentration variations for reactants, namely by giving a designation atJ to the coefficient that the ith substance has when it enters the jth complex. We then obtain... 

It was Pasteur, in the middle of the 19th century, who first recognized the breaking of chiral symmetry in life. By crystallizing optically inactive sodium anmonium racemates, he separated two enantiomers of sodium ammonium tartrates, with opposite optical activities, by means of their asymmetric crystalline shapes [2], Since the activity was observed even in solution, it was concluded that optical activity is due to the molecular asymmetry or chirality, not due to the crystalline symmetry. Because two enantiomers with different chiralities are identical in every chemical and physical property except for optical activity, in 1860 Pasteur stated that artificial products have no molecular asymmetry and continued that the molecular asymmetry of natural organic products establishes the only well-marked line of demarcation that can at present be drawn between the chemistry of dead matter and the chemistry... 

Before detailed conclusions are presented with regard to the physical meaning of the present model more fundamental studies are needed. While it is clear that ethanol "induces" new pores or "activates" latent pores in hairless mouse stratum corneum at high ethanol concentrations (10), the role of ethanol at lower concentrations is less clear at this moment. It is well known (12 ) that ethanol at low concentrations, may "fluidize" bilayers, thus leading to changes in both partitioning and diffusivity. Thus a complete description for permeation through stratum corneum will have to consider the effects of adjuvants on the properties of lipid bilayers in addition to the pore model described here. 

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