Dipole moment, water, molecule

Nuclear magnetic resonance T], correlation time for rotation of the dipole moment Water molecule orientation (NMR line shape)... 

Such a comparative study has been made by Byakov and his collaborators.29 255 They have shown that in the case of water the main contribution to the loss rate given by formula (6.3) comes from excitation of intramolecular vibrations rather than from dipole relaxation. This is all the more so in nonpolar media where the main channel of continuous losses is not the relaxation of constant dipole moments (which are zero) but the polarization losses due to the electron-inducing dipole moments in molecules. The possible exceptions are the media consisting of molecules with a high degree of symmetry, such as methane and neopentane, which have no active vibrations in the IR region. 

Polarity is the extent to which a substance, at molecular level, is characterized by a non-symmetrical distribution of electron density. Polarity is often expressed as dipole moment, which is a function of the magnitude of the partial charges on the molecule, and the distance between the charges. Substances that have larger dipole moments have greater polarity than substances with lower dipole moments. Water and acetone, for example, have dipole moments of 1.85 and 2.80, respectively. Benzene and carbon tetrachloride are nonpolar and have dipole moments of zero. 

As a consequence, water dissolves many salts and many molecules that have large dipole moments. Water does not dissolve molecules that lack a charge or a substantial dipole moment. Nonpolar molecules that contain many carbon-hydrogen and carbon-carbon units are called hydrocarbons and are well known as oils and fats. Their nonpolarity is the general reason that oil (petroleum oil and vegetable oil alike) and water do not mix. 

The situation was viewed at first as somewhat surprising since, in such interactions, considered to be essentially ion-dipole interactions, the molecule with the larger dipole moment, water (p = 1.85 debye units) should have been taken up preferentially to ammonia (n = 1.47). 

Giant molecules zeolites de-ionized" water., Temporary hardness and permanent hardness methods of softening water. Heat capacity (specific heat). Van der Waals attraction, boiling point, melting point-dependence on molecular size. Electric dipole moments of molecules—effect on boiling point. Ionic dissocia-... 

As we saw in Chapter 12, water is a polar molecule—it has a dipole moment. When molecules with dipole moments are put together, they orient themselves to take advantage of their charge distributions. Molecules with dipole moments can attract each other hy lining up so that the positive and negative ends are close to each other, as shown here. 

Fig. 1 Dipole moments per molecule for a sequence of planar water chains, with consecutive 0—0 internuclear separations of 2.87 A and O—H bond lengths of 1.00 A and internal angle 105°, as calculated by QTPIE (black solid line), DF-LMP2/aug-cc-pVIZ (blue broken line), AMOEBA (green short-dashed line), QEq (brown dashed line), and reparameterized QEq (purple dash-dotted line). The parameters used for the QTPIE and QEq models are given in Table 2...

The average molecular dipole moment of molecules in a condensed phase is not well defined, but it is very common for it to be calculated from partial atomic charges or other anal3fsis methods. We calculated the average dipole moment of water in the liquid < /ttiiq > to be 2.524 0.002 D, which represents an increase of 35% relative to the gasphase equilibrium-geometry value (1.88 D... 

Microwave radiation consists of electric and magnetic components like other electromagnetic radiations. To describe and analyze interaction of electromagnetic radiation with microcapsules water suspension is a difficult task. These suspensions consist of a great number of charged polymer molecules and dipole water ones thus the electric field acts on dipole moments of molecules. It was established that irradiation of... 

Of course, any diatomic (two-atom) molecule that has a polar bond also will show a molecular dipole moment Polyatomic molecules also can exhibit dipolar behavior. For example, because the oxygen atom in the water molecule has a greater electronegativity... 

The SPC/E model approximates many-body effects m liquid water and corresponds to a molecular dipole moment of 2.35 Debye (D) compared to the actual dipole moment of 1.85 D for an isolated water molecule. The model reproduces the diflfiision coefficient and themiodynamics properties at ambient temperatures to within a few per cent, and the critical parameters (see below) are predicted to within 15%. The same model potential has been extended to include the interactions between ions and water by fitting the parameters to the hydration energies of small ion-water clusters. The parameters for the ion-water and water-water interactions in the SPC/E model are given in table A2.3.2. 

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