Lewis relationship

Lewis relationship The ratio of the convective heat-transfer coefficient to the evaporative heat-transfer coefficient. 

The Lewis relationship (1.198), which we have already discussed, allows us to relate the mass transfer coefficient (3G approximately to the heat transfer coefficient... 

As indicated by Figure 12.59, the final step is to convert (wet or dry) to the overall column efficiency This is done using the Lewis relationships ... 

For analogous relationships between h and ki if two conventional relationships were considered [8. ], and the Lewis relationship,... 

Lewis relationship was used to compute m[A. The correlation was chosen as the best of several correlating parameters investigated. 

In air conditioning processes, the heat and mass transfer analogy is usually expressed using the Lewis relationship... 

Eq. (5.3-26a) is known as the Lewis relationship. It has been tested with a number of systems involving silica gel and activated carbon. This equation relates the amounts adsorbed in multicomponent system (C j) to those for pure component systems (C j) evaluated at the hypothetical pressure P . 

Although eq. (5.3-26) were derived from thermodynamic analysis (Section 5.3-2), the Lewis relationship can be derived by the following alternative approach, which assumes the adsorption is by a micropore filling mechanism. The derivation of this equation is as follows. The maximum volumetric capacity for micropore filling is Wo, which is assumed the same for all sorbates. Therefore, the maximum number of moles of adsorbed species is ... 

T 0 calculate Vj and V2, the following Lewis relationship for a binary system [60] is used ... 

The Lewis relationship has its theoretical basis in micropore filling with the assumption that the adsorbed phase is ideal [2],... 

Several alternative attempts have been made to quantify Lewis-acid Lewis-base interaction. In view of the HSAB theory, the applicability of a scale which describes Lewis acidity with only one parameter will be unavoidably restricted to a narrow range of struchirally related Lewis bases. The use of more than one parameter results in relationships with a more general validity ". However, a quantitative prediction of the gas-phase stabilities of Lewis-acid Lewis-base complexes is still difficult. Hence the interpretation, not to mention the prediction, of solvent effects on Lewis-add Lewis-base interactions remains largely speculative. 

This chapter sets the stage for all of the others by reminding us that the relationship between structure and properties is what chemistry is all about It begins with a review of Lewis structures moves to a discussion of the Arrhenius Brpnsted-Lowry and Lewis pictures of acids and bases and the effects of structure on acidity and basicity... 

The electrophile (E ) m this reaction is mtromum ion (0=N=0) The charge distn bution m mtromum ion is evident both m its Lewis structure and m the electrostatic potential map of Figure 12 2 There we see the complementary relationship between the electron poor region near nitrogen of NO, and the electron rich region associated with the TT electrons of benzene... 

P. A. Lewis, ed.. Pigment Handbook, 3 vols., John Wiley Sons, Inc., New York. Vol. 1 Properties Economics, 2nd ed., 1988. Vol. 2 Applications C Markets, 2nd ed., 1988. Vol. 3 Characterisation Physical Relationships, 1973. John Wiley Sons, Inc. 

Overall Column Efficiency Calculated values of E, , must be corrected for entrainment, if any, by the Colburn equation [Eq. (14-101)]. The resiJting corrected efficiency is then converted to column efficiency by the relationship of Lewis [Ind. Eng. Chem., 28, 399 (1936)] ... 

The term nucleophilicity refers to the effect of a Lewis base on the rate of a nucleophilic substitution reaction and may be contrasted with basicity, which is defined in terms of the position of an equilibrium reaction with a proton or some other acid. Nucleophilicity is used to describe trends in the kinetic aspects of substitution reactions. The relative nucleophilicity of a given species may be different toward various reactants, and it has not been possible to devise an absolute scale of nucleophilicity. We need to gain some impression of the structural features that govern nucleophilicity and to understand the relationship between nucleophilicity and basicity. ... 

In the Lewis acid mediated reaction the developing carbenium ion in C is stabilized by the nearby 7t-electrons of the titanium or aluminum enolate. This generates as the major diastereomer the 3,3a-/r .v-relationship between the substitution at the ring junction and the vinyl group at C-3 via a synclinal transition state. 

With sufficient data, equation (6.47) can be integrated to give o,. However, adequate data are available for only a few mixtures, and approximate relationships are used to estimate o,. The simplest approximation uses the Lewis and Randall rule given by11... 

Nitrobenzenediazoate can be considered as an azo compound comparable to an azobenzene having one electron acceptor and one donor on each side of the azo group the acceptor-donor relationship is more dominant in the (Z) -> (E) diazoate pair than in the diazohydroxide pair. The N=N rotation mechanism of the diazoate pair is therefore the favored process (E = 84 kJ mol-1 Lewis and Hanson, 1967). On the other hand, 4-C1 is not a substituent with a —M effect therefore it does not reduce the double-bond character of the N = N bond and the mechanism involving inversion at the N((3)-atom becomes dominant. The activation energy of the latter process (E = 104 kJ mol-1 Schwarz and Zollinger, 1981) is higher than that of the N = N rotation mechanism for the 4-nitro derivative, but it is reasonable to assume that it is lower than that for N = N rotation in the 4-chloro derivative. Furthermore, one can conclude that N-inversion is more favorable in the diazohydroxide than in the diazoate. ... 

These results clearly demonstrate that linear energy relationships can be established for the formation of hydrogen bonds between numerous Lewis bases (including sulphoxides) with Lewis acids. 

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