Water hydrogen-bonded structure

Shen and co-workers employed the phase-sensitive SFG-VS measurement and studied the ssp SFG-VS spectra of the Nal aqueous solution surfaces in comparison with the neat air-water interface. The authors concluded that the presence of 1 anion near the interface region may not disturb the water molecular structure at the topmost surface layer, while it can reorientate the water molecules in the subphase. Their data confirmed the influence of the interfacial water hydrogen bonding structure by the 1 anions of the previous SFG studies. 

The presence of alcohols in the aqueous medium generally decreases grafting. This is expected since the addition of alcohol breaks the tetrahedral hydrogen bonded structure of water and thus disturbs the association of active sites with water. This will lead to a decrease in grafting. In the presence of alcohols, chain... 

Water has many unusual properties in addition to its high boiling point. As pointed out in Chapter 8, it has a very high specific heat, 4.18 J/g °C. Its heat of vaporization per gram, 2.26 kj/g, is the highest of all molecular substances. Both of these properties reflect the hydrogen-bonded structure of the liquid. Many of these bonds have to be broken when the liquid is heated all of them disappear on boiling. 

During the reaction, protons are extracted from the brucite lattice. Infrared spectra [24, 25, 31] show that during charge the sharp hydroxyl band at 3644 cm" disappears. This absorption is replaced by a diffuse band at 3450 cm"1. The spectra indicate a hydrogen-bonded structure for ft-NiOOH with no free hydroxyl groups. ft-NiOOH probably has some adsorbed and absorbed water. However, TGA data... 

Figure 4.11 Hydrogen bonded structures of the water of hydration in Na2SO410H2O.

Note that the m(dstrong electrolytes in dilute solution. It results because the charged ions break up the hydrogen bonded structure of the water and decrease the heat capacity of the solution over that of pure water. Thus, the contribution of Cp. 2 to Cp m is negative. 

The incorporation of water in the structure of cellulose influences. Upon the hydrogen bond structure of the macromolecule. A great deal of work has been done in this area. Calorimetric methods have been invaluable in helping to solve the problem 23 It is, however evident that solid-state NMR spectroscopy may also give valuable information. 

If the principal cohesive forces between solute molecules are London forces, then the best solvent is likely to be one that can mimic those forces. For example, a good solvent for nonpolar substances is the nonpolar liquid carbon disulfide, CS2-It is a far better solvent than water for sulfur because solid sulfur is a molecular solid of S8 molecules held together by London forces (Fig. 8.19). The sulfur molecules cannot penetrate into the strongly hydrogen-bonded structure of water, because they cannot replace those bonds with interactions of similar strength. 

Fig. 22. The hydrogen-bonded structure of (Me3Si)3CSiF(OH)2, showing the hexameric unit containing two water molecules, [(Me3Si)3CSiF(0H)2V2H20, with hydrogen atoms and methyl groups omitted for clarity (310).

Fig. 8. Stereoscopic illustration of the inclusion compound of host 5 (folded conformation) with acetic acid and 2 mol of water. Host-host and host-water hydrogen bonding interactions stabilize the structure. The solvation layers consist of cyclic carboxy dimers of acetic acid surrounded by water species (crystal data a = 7.857, b = 11.379,c = 13.831 A,a = 92.50,/i = 101.21, y = 101.12°, space group Pi taken from Ref. 351)...

ICC Termination Act of 1995, 25 331, 326 Ice. See also Water entries elastic properties, 5 614t hydrogen-bonded structure of, 26 15 properties of, 26 17t Ice wines, 26 315 Iceberg model, 23 95 Ice formation, in food processing, 72 82 Iceland, bioengineering research program, 7 702... 

These results reflect the point made earlier that the structure of water is determined by the competition between the water-metal and water-water interactions. When the former are weak with no underlying lattice structure, the water structure near the metal is similar to the bulk structure. When the water-metal interactions are stronger, the water is much more structured. This was clearly demonstrated by Lee et who observed much more pronounced density oscillations when the water hydrogen-bonding interactions were turned off. 

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