Water unusual properties

Many of the unusual properties of the perfluorinated inert fluids are the result of the extremely low intermolecular interactions. This is manifested in, for example, the very low surface tensions of the perfluorinated materials (on the order of 9-19 mN jm. = dyn/cm) at 25°C which enables these Hquids to wet any surface including polytetrafluoroethene. Their refractive indexes are lower than those of any other organic Hquids, as are theh acoustic velocities. They have isothermal compressibilities almost twice as high as water. Densities range from 1.7 to 1.9 g/cm (l )-... 

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. 

The unusual thermal stability and water uptake properties are due to the formation of a three-dimensional network in polysaccharides at high processing temperatures [12]. 

These exceptional properties, exclusive to water, result from the structure of its molecule and the nature of the bonds (links) between its constituent atoms. The molecule of water is made up of two atoms of hydrogen bonded to one of oxygen, so that its formula is H20. The composition gives no clue as to its unusual properties, however. It is the special architecture... 

Despite the efforts of a large number of scientists from a wide array of disciplines, to date, no single model successfully accounts for all the properties of real water. However, with each passing year, experimental and theoretical studies continue to contribute important pieces to the puzzle of the unusual properties of water, forming an increasingly coherent picture of the true nature of water. 

Hydrogen bonding explains why water has such unusual properties. We will discuss these properties later in this chapter. 

The solubility of water in the organic phase as welf Ss its temperature dependence is well represented. This system exhibits the unusual property of having opposite signs for the temperature depence of the solubilities in the two phases. 

You might think that because water is everywhere, it s a very simple substance. Not true Water has some very unusual properties. That s a good thing because those unusual properties make it possible for us to skate on frozen ponds, for fish to survive the winter, for plants to grow, and even for there to be life at all. 

The unusual properties of water are largely accounted for by the formation of hydrogen bonds. These interactions also prove to be critical for the structnre and function of the proteins and nucleic acids. 

Since water is a constituent in a great many inorganic solids, and is involved in all chemical reactions performed in aqueous solutions, is the most widely distributed of all cations. When present, it usually plays a pivotal role in the chemistry, whether in the solid or the liquid state (Chapter 5). It is therefore important that its behaviour and the origin of its unusual properties be properly understood. 

An analysis of the Wannier functions in CPMD simulations of one dimethyl sulfoxide (DMSO) molecule dissolved in water was carried out by us in 2004 in order to gain more insight into the unusual properties of the DMSO-water mixture (72). In this special case, we have utilized MLWCs to calculate molecular dipole moments of the DMSO molecule in gas phase and aqueous solution. Comparing those two a large increase of the local dipole... 

Some physical properties of water are shown in Table 7.2. Water has higher melting and boiling temperatures, surface tension, dielectric constant, heat capacity, thermal conductivity and heats of phase transition than similar molecules (Table 7.3). Water has a lower density than would be expected from comparison with the above molecules and has the unusual property of expansion on solidification. The thermal conductivity of ice is approximately four times greater than that of water at the same temperature and is high compared with other non-metallic solids. Likewise, the thermal dif-fusivity of ice is about nine times greater than that of water. 

Hydrogen Bonding Gives Water Its Unusual Properties... 

Water has a higher melting point, boiling point, and heat of vaporization than most other common solvents (Table 2-1). These unusual properties are a consequence of... 

Organisms have effectively adapted to their aqueous environment and have evolved means of exploiting the unusual properties of water. The high specific heat of water (the heat energy required to raise the temperature of 1 g of water by 1 °C) is useful to cells and or-... 

Triflate salts, mainly scandium triflate273 and lanthanide(III) triflates,274,275 have found increasing use in various aromatic substitutions. They have some unusual properties specifically, they may be used in catalytic quantity and active even in the presence of water. They are also easily recyclable via aqueous workup. 

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