Water, structures

Falk and Ford concluded that hydrogen bonds in liquid water have a broad smooth single-peaked distribution of strengths which gradually shifts with temperature. At one end of this distribution the hydrogen bond strengths are comparable to 

Frequency assignments for associational bands found in part of the infrared spectra of water and of D2O were proposed by Williams (1966). The bands were at 2130, 3950, and 5600 cm for HjO and 1555, 2900, and 4100 cmfor DjO. 

Draegert et al. (1966) investigated the far-infrared spectrum of liquid water between 30cm and 1200cm . They reported a broad major band with maximum absorption at 685 + 15 cm together with a second, less intense overlapping band at 170 + 15 cm In liquid D2O the corresponding bands appeared at 505 + 15 cm and 165 + 15 cm respectively. 

Deryagin and Churayev (1968) reported on a form of water with properties different from those well established for water, and the new form has been referred to as anomalous water. This water has been prepared by Fedyakin (1962) in a sealed glass capillary 2 to 4 jU in diameter and later by Deryagin et al. (1965) by the condensation of water vapor in glass and fused quartz capillaries at relative pressures somewhat less than unity. Among the properties of this water, renamed polywater by Lippincott et al. (1969), are (1) low vapor pressure (2) solidification at — 40°C or lower temperatures to a glass-like state with a substantially lower expansion than that of ordinary water when it freezes and (3) a density of I.OI to I.4g/cm and stability to temperatures of the order of 500°C. 

Although the vibrational spectra of polywater appear to be completely unique and different from those of any known substance (Lippincott et al., 1969), these spectra have several features that are quite similar to those of hydrogen-bonded systems which have very strong symmetric hydrogen bonds such as those occurring in KHF2 and 

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Surfaces can be active in inducing blood clotting, and there is much current searching for thromboresistant synthetic materials for use in surgical repair of blood vessels (see Ref. 111). It may be important that a protective protein film be strongly adsorbed [112]. The role of water structure in cell-wall interactions may be quite important as well [113]. 

One anomaly inmrediately obvious from table A2.4.2 is the much higher mobilities of the proton and hydroxide ions than expected from even the most approximate estimates of their ionic radii. The origin of this behaviour lies in the way hr which these ions can be acconmrodated into the water structure described above. Free protons cannot exist as such in aqueous solution the very small radius of the proton would lead to an enomrous electric field that would polarize any molecule, and in an aqueous solution the proton inmrediately... 

Walrafen G E 1967 Raman spectral studies of the effects of temperature on water structure J. Chem. Phys. 47 114-26... 

The individual weights range from less than 1 kg to several 100 kg the latter is particularly used in steel-water structures. Anodes for the external protection of ships are heavier than 40 kg only in exceptional cases. According to need, anodes are combined into groups whose total weight amounts to several hundred kilograms. 

In choosing a site for protection installations for steel-water structures, decisive factors are the location in the harbor area and the need to keep the lengths of cable to the protected object and anode as short as possible where very high protection currents are involved. 

Fig. 5(a) contains the oxygen and hydrogen density profiles it demonstrates clearly the major differences between the water structure next to a metal surface and near a free or nonpolar surface (compare to Fig. 3). Due to the significant adsorption energy of water on transition metal surfaces (typically of the order of 20-50kJmoP see, e.g., [136]), strong density oscillations are observed next to the metal. Between three and four water layers have also been identified in most simulations near uncharged metal surfaces, depending on the model and on statistical accuracy. Beyond about...

The major difference of the water structure between the liquid/solid and the liquid/liquid interface is due to the roughness of the liquid mercury surface. The features of the water density profiles at the liquid/liquid interface are washed out considerably relative to those at the liquid/solid interface [131,132]. The differences between the liquid/solid and the liquid/liquid interface can be accounted for almost quantitatively by convoluting the water density profile from the Uquid/solid simulation with the width of the surface layer of the mercury density distribution from the liquid/liquid simulation [66]. 

In the Gaussian approximation the water-water structure factor iS vro (A ) for (1) is given by... 

In the real space the correlation function (6) exhibits exponentially damped oscillations, and the structure is characterized by two lengths the period of the oscillations A, related to the size of oil and water domains, and the correlation length In the microemulsion > A and the water-rich and oil-rich domains are correlated, hence the water-water structure factor assumes a maximum for k = k 7 0. When the concentration of surfac-... 

The present interpretation of water structure is that water molecules are connected by uninterrupted H bond paths running in every direction, spanning the whole sample. The participation of each water molecule in an average state of H bonding to its neighbors means that each molecule is connected to every other in a fluid network of H bonds. The average lifetime of an H-bonded connection between two HgO molecules in water is 9.5 psec (picoseconds, where 1 psec =10 sec). Thus, about every 10 psec, the average HgO molecule... 

The resistance of groundbeds for protection of pipelines or anodes for protection of jetties or other sea-water structures, is usually calculated in accordance with the formulae originally developed by Dwight. However, the following abridged formulae are normally used and are sufficient for all practical purposes ... 

The electrodes designed for permanent installation on deep-water structures must be protected from damage but must also correctly view the protected structure. Thus electrodes must be closely placed to the structure to avoid the incorporation of an IR element in the potential measured, but must not create a protection shadow which could cause a false indication of the protection level. 

In the case of a singly charged atomic ion in aqueous solution we have estimated the mutual potential energy between the ion and an adjacent water molecule when they are of nearly the same size, and have found the value to be about four times as great as the mutual potential energy of two adjacent water molecules. We conclude then that in the vicinity of an atomic ion the water structure will have to build itself round the ion, insofar as this is possible. 

It will be recalled that in Fig. 28 we found that for the most mobile ions the mobility has the smallest temperature coefficient. If any species of ion in aqueous solution at room temperature causes a local loosening of the water structure, the solvent in the co-sphere of each ion will have a viscosity smaller than that of the normal solvent. A solute in which both anions and cations are of this type will have in (160) a negative viscosity //-coefficient. At the same time the local loosening of the water structure will permit a more lively Brownian motion than the ion would otherwise have at this temperature. Normally a certain rise of temperature would be needed to produce an equal loosening of the water structure. If, in the co-sphere of any species of ion, there exists already at a low temperature a certain loosening of the water structure, the mobility of this ion is likely to have an abnormally small temperature coefficient, as pointed out in Sec. 34. 

Let us now ask how this value could be used as a basis from which to measure the local disturbance of the water structure that will be caused by each ionic field. The electrostriction round each ion may lead to a local increase in the density of the solvent. As an example, let us first consider the following imaginary case let us suppose that in the neighborhood of each ion the density is such that 101 water molecules occupy the volume initially occupied by 100 molecules and that more distant molecules are not appreciably affected. In this case the local increase in density would exactly compensate for the 36.0 cm1 increment in volume per mole of KF. The volume of the solution would be the same as that of the initial pure solvent, and the partial molal volume of KF at infinite dilution would be zero. Moreover, if we had supposed that in the vicinity of each ion 101 molecules occupy rather less than the volume initially occupied by 100 molecules, the partial molal volume of the solute would in this case have a negative value. 

Water, structure of, 46-49, 52, 54r-55,248 viscosity of, table, 266 Water molecule, 47-50... 

Solvation and especially hydration are rather complex phenomena and little is known about them. Depending on the kind of molecular groups, atoms or ions interacting with the solvent, one can differ between lyo- or hydrophilic and lyo-or hydrophobic solvation or hydration. Due to these interactions the so-called liquid structure is changed. Therefore it seems to be unavoidable to consider, at least very briefly, the intermolecular interactions and the main features of liquids, especially water structure before dealing with solvation/hydration and their effects on the formation of ordered structures in the colloidal systems mentioned above. 

More complicated and less known than the structure of pure water is the structure of aqueous solutions. In all cases, the structure of water is changed, more or less, by dissolved substances. A quantitative measure for the influence of solutes on the structure of water was given in 1933 by Bernal and Fowler 23), introducing the terminus structure temperature, Tsl . This is the temperature at which any property of pure water has the same value as the solution at 20 °C. If a solute increases Tst, the number of hydrogen bonded water molecules is decreased and therefore it is called a water structure breaker . Vice versa, a Tsl decreasing solute is called a water structure maker . Concomitantly the mobility of water molecules becomes higher or lower, respectively. 

It is possible to indicate by thermodynamic considerations 24,25,27>, by spectroscopic methods (IR28), Raman29 , NMR30,31 ), by dielectric 32> and viscosimetric measurements 26), that the mobility of water molecules in the hydration shell differs from the mobility in pure water, so justifying the classification of solutes in the water structure breaker and maker, as mentioned above. 

Similar conclusions were obtained from lH and 31P NMR and also from IR studies of egg phospholecithin reversed micelles in benzene by Boicelli et al. 58 61). According to the results of these experiments the water structure within the reversed phospholecithin micelles alters considerably compared with water in bulk. This becomes evident from the shortening of the relaxation time T, of the water protons split into two relaxation times T1A and T1B, indicating that there are at least two... 

As mentioned above, water structure in reversed micelles deviates considerably from the structure in the bulk-phase. Therefore, the hydration shell of macromolecules entrapped in reversed micellar systems should be changed and thus also their conformation. According to the results of several authors this is indeed the case. 

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