Water grounding hypothesis

The normal substances, however, really exhibit small deviations which are all the greater the more complex is the molecule of the substance. The theory of van der Waals, or in fact any hypothesis from which a theorem of corresponding states could be derived, assumes however that the transition from the gaseous to the liquid state, as well as the changes of density in either state, result from alterations in the propinquity of molecules which otherwise remain unaltered. Any association or dissociation of the substance would therefore give rise to abnormalities, and in fact the substances which deviate most from the normal relations (e.g.l water, acetic acid) are those which appear, on other grounds, to be associated in the liquid state. In the case of acetic acid the commencement of polymerisation, even in the state of vapour, is evident from the abnormal densities. 

Early scientists and philosophers invested much effort in the search for the fundamental substance or substances—the simplest kind of matter that comprises the world and all of its various materials. The ancient Greek philosopher Thales (ca. 635-556 b.c.e.) postulated that water is the fundamental substance. Although this idea may not sound realistic today, the hypothesis was a reasonable one. Life depends on water and Earth contains a huge quantity of water in oceans and rivers water falls from the sky as rain and seeps through the ground in wells. The ancient Greek philosopher Empedocles (ca. 495-435 b.c.e.) expanded the list of fundamental substances to four—water, earth, air, and fire. 

In a review of the proficiencies of enzymes and how they achieve them, it was claimed that ground-state conformations and transition state stabilization cannot explain the very large efficiencies of enzymes instead, they must proceed, it was concluded, by covalent enzyme-substrate intermediates.73 A riposte to this contentious hypothesis has appeared, claiming that account was not taken of the fact that high enzyme efficiency is determined by the value for the water reaction k0 rather than by the enzymatic rate constant kcat/kM.14... 

Fig. 13.5 Noble gases dissolved in thermal waters in the Jordan Rift Valley. (Data from Mazor, 1972.) The nonsaline waters lie between the values of air-saturated water (ASW) at 15 and 25 °C, demonstrating the meteoric (atmospheric) origin and the closed-system conditions that prevailed in the ground. The saline Tiberias hot water is suggested to have originated by saline water entrapment, a hypothesis supported by the lower noble gas content (Mazor, 1972).

Between the extreme views of in situ production and whole crustal flux, there are alternative explanations for the observed He concentrations in ground water. Andrews and Lee (1979) and Tolstikhin et al. (1996) suggested that diffusion from the adjacent confining layers constituted the major source of He. This hypothesis is supported by the widespread correlation between He and Cf in ground waters, since both species could... 

There are a number of studies using housing markets to examine health risks. These studies are based on the hypothesis that house characteristics yielding differences in health risks across houses should be reflected in property value differentials. Examples are provided by air pollution (see Fortney, 1981), exposure to hazardous waste (Kohlhase, 1991), ground-water contamination (Malone and Barrows, 1990), and radon radiation (Soderqvist, 1991). 

The hydrolysis of anhydrides is in many ways similar to the hydrolysis of esters. The volume of activation for the acid-catalyzed hydrolysis of acetic anhydride in 44-1% w/w acetone-water at 0°C is —17T l-3 cm mole (Koskikallio et al., 1959). The volume of activation for the hydrolysis of methyl acetate in the same solvent is — 13-6 cm mole- (Withey et al., unpublished), and so it seems likely that the mechanism for acetic anhydride is bimolecular. This was originally taken as a failure of the Zucker-Hammett hypothesis (Koskikallio et al., 1959) because the rate in water is approximately proportional to (Gold and Hilton, 1955). However, it appears (Bunton and Perry, 1960), largely on the grounds of the changing entropy of activation with changing solvent, that the mechanism may change between pure water and aqueous dioxane. 

Nevertheless, Rogers and Bruice s model does support the charge-relay hypothesis because larger rate enhancements have been reported when nearly anhydrous acetonitrile or toluene is employed. Under these conditions, the hydrogen bond system is locked inside and does not exchange with the medium. In this situation scheme b, general-base assisted water attack, is possible where a dipolar transition state is formed from a neutral ground state. This would happen in acetonitrile only if a nearby carboxylate (anion) is present. 

---