London effect

The relative contributions to van der Waals interactions arising from the Debye, Keesom, and London effects... 

It is clear from Table 1 that, for a few highly polar molecules such as water, the Keesom effect (i.e. freely rotating permanent dipoles) dominates over either the Debye or London effects. However, even for ammonia, dispersion forces account for almost 57% of the van der Waals interactions, compared to approximately 34% arising from dipole-dipole interactions. The contribution arising from dispersion forces increases to over 86% for hydrogen chloride and rapidly goes to over 90% as the polarity of the molecules decrease. Debye forces generally make up less than about 10% of the total van der Waals interaction. 

While there is no permanent separation of charge in such homoatomic molecules, there may be a temporary separation of the charge present in the covalent bond. The electron density within the molecular orbital is subject to random fluctuations, which result in a temporary separation of charge called the London effect. These fluctuations average to zero over time. 

London effect The temporary creation of a dipole in a molecule caused by the random movement of electrons within a molecular bond. 

R. K. Shah and A. L. London, Effects of Nonuniform Passages on Compact Heat Exchanger Performance, ASME J. Eng. Power, Vol. 102A, pp. 653-659,1980. 

Me Arragher, J.S. and al. (1990), The effects of temperature and fuel volatility on evaporative emissions from european cars . /. Mech. Eng., No. 394/028, London. 

Leone S R 1989 Laser probing of ion collisions in drift fields state excitation, velocity distributions, and alignment effects Gas Phase Bimolecular Collisions ed M N R Ashford and J E Baggett (London Royal Society of Chemistry)... 

Assuming London-dispersion and electrostatic interactions to be dominant in arene - arene interactions (see Section 3.2.7), the solvent effect on the enantioselectivify is anticipated to be influenced by the polarisability and polarity of the solvent. The arene -arene interaction is inferred to... 

Hassel shared the 1969 Nobel Prize in chemistry with Sir Derek Barton of Imperial College (London) Barton demonstrated how Hassel s structural results could be extended to an analysis of conformational effects on chemical reactivity... 

Boiling Point When describing the effect of alkane structure on boiling point m Sec tion 2 17 we pointed out that van der Waals attractive forces between neutral molecules are of three types The first two involve induced dipoles and are often referred to as dis persion forces or London forces... 

Induced dipole/mduced dipole attraction (Section 2 17) Force of attraction resulting from a mutual and complemen tary polanzation of one molecule by another Also referred to as London forces or dispersion forces Inductive effect (Section 1 15) An electronic effect transmit ted by successive polanzation of the cr bonds within a mol ecule or an ion... 

For large deformations or for networks with strong interactions—say, hydrogen bonds instead of London forces—the condition for an ideal elastomer may not be satisfied. There is certainly a heat effect associated with crystallization, so (3H/9L) t. would not apply if stretching induced crystal formation. The compounds and conditions we described in the last section correspond to the kind of system for which ideality is a reasonable approximation. 

Effect of Conditioning Humidity on the Electrical Resistance of Rayon Yams, British Cotton Industry Research Association, London, 1945. 

J. P. Hanrahan and co-workers, Beta-Agonists and Their Effects on Animal Growth and Carcass Quality, Elsevier Apphed Science, London, 1987, pp. 106-118. 

Th. E. Tadros, The Effect of Polymers on Dispersion Properties, Academic Press, Inc., London, 1982. 

The same money invested in a project with a (DCFRR) of 10 percent would, by Eq. (9-108), obtain an entrepreneurial return i = 8.37 percent on the whole investment, i.e., 8.37/ 100. Investment of the entrepreneur s own money would only achieve an aftertax return of (0.1)(1 — 0.40) = 6 percent on 50, or 3/ 100 of total investment. The incentive to the entrepreneur to manage the projeci thus corresponds to a tax-free income of 5.37/ 100 of total investment. In practice, money is borrowed from more than one source at different interest rates and at different tax liabihties. The effective cost of capital in such cases can be obtained by an extension of the above reasoning and is treated in detail by A. J. Merrett and A. Sykes Capital Budgeting and Company Finance, Longmans, London, 1966, pp. 30 8). 

One cannot quantitatively predict the effect of the various interfacial phenomena thus, these phenomena will not be covered in detail here. The following literature gives a good general review of the effects of interfacial phenomena on mass transfer Goodridge and Robb, Ind. Eng. Chem. Fund., 4, 49 (1965) Calderbank, Chem. Eng. (London), CE 205 (1967) Gal-Or et al., Ind. Eng. Chem., 61(2), 22 (1969) Kintner, Adv. Chem. Eng., 4 (1963) Resnick and Gal-Or, op. cit., p. 295 Valentin, loc. cit. and Elenkov, loc. cit., and Ind. Eng. Chem. Ann. Rev. Mass Transfer, 60(1), 67 (1968) 60(12), 53 (1968) 62(2), 41 (1970). In the following outhne, the effects of the various interfacial phenomena on the factors that influence overall mass transfer are given. Possible effects of interfacial phenomena are tabulated below ... 

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