Heavy water viscosity

Self diffusion coefficients can be obtained from the rate of diffusion of isotopically labeled solvent molecules as well as from nuclear magnetic resonance band widths. The self-diffusion coefficient of water at 25°C is D= 2.27 x 10-5 cm2 s 1, and that of heavy water, D20, is 1.87 x 10-5 cm2 s 1. Values for many solvents at 25 °C, in 10-5 cm2 s 1, are shown in Table 3.9. The diffusion coefficient for all solvents depends strongly on the temperature, similarly to the viscosity, following an Arrhenius-type expression D=Ad exp( AEq/RT). In fact, for solvents that can be described as being globular (see above), the Stokes-Einstein expression holds ... 

Whereas light and heavy water have nearly identical relative permittivities and dipole moments, it can be concluded from the greater boiling point, heat of vaporization, density, and viscosity of heavy water, that liquid D2O is more structured than the already highly structured H2O at room temperature cf. Fig. 2-1 in Section 2.1). This is also consistent with the fact that salts acting as structure-breakers are generally less soluble in D2O than H2O [446]. 

The 10% mass change in water by the replacement of protium by deuterium results in substantial changes in many commonly known properties of water. In Table 3, a number of physical properties of normal water, FI2O, and heavy water, D2O, are compared. The viscosity of D2O is 25% higher than that of H2O at 25 °C, which is the most conspicuous difference between H2O and D2O. 

Long ago Bernal and Fowler (1933) introduced the concept of the structural temperature of aqueous solutions. This is that temperature, Tsu, at which pure water would have effectively the same inner structure as the water in a solution at the temperature T. They suggested that Tstr could be estimated from viscosity, x-ray diffraction, Raman spectroscopy, etc., but did not provide explicit methods and values. TheD20 vs. H2O isotope effects on x-ray Raman spectra indicate (Bergmann et al. 2007) that D2O has a structural temperature lower by 20 K than H2O at ambient conditions. This is ascribed to the inherently stronger hydrogen bonding in the heavy water. The concept of structural temperature has by now been practically abandoned, however. 

The compressibility of liquid water is anomalous in that it decreases with increasing temperature, passes through a minimum at 46° C, and then increases again. The compressibility of heavy water follows a similar pattern, but the minimum is about 3°C higher than for H2O. The ratio of the viscosities of liquid D2O and H2O is 1.23 at 25°C, which is much larger than the ratio of the square-roots of the molecular masses (1.0544). However, according to Vedamuthu et al. (1996) the thermal offset effect, that is, the difference (6.498°C) between the temperatures of the maximum densities of H2O (3.984°C) and D2O (11.185°C) should be taken into account when one compares the different properties of the two liquids. Thus, for example, the viscosity of D2O at 26.498° C would be the viscosity of H2O at 20° C multiplied by 1.0544, the square-root of the mass ratio of the two isotopic molecules (Cho et al. 1999). This supports the view that the viscosity isotope effect on liquid water is not a rotational, but a translational mass effect. The concept of thermal offset effect can be used in correlating the various thermodynamic properties of liquid H2O, D2O, and T2O. 

This treatise is an exhaustive compilation of physical data on heavy water (deuterium oxide). Some of the more relevant properties that are covered include densities, critical constants, vapor pressures, enthalpies of transition, viscosity, and thermal conductivity, equation of state, and tables of thermodynamic properties as functions of temperature and pressure. 

The physical properties of light water (H O), heavy water (D O) and superheavy water (T O) at room temperature (20°C) are listed in Table 20.14, while polynomial equations for calculating the density, viscosity, surface tension and vapor pressure of water at various temperature are provided in Table 20.15. 

Vicinal water shows very interesting structural transitions near temperatures of 15,30, and 45°C [232-234], showing maxima in viscosity, disjoining pressure, and entropy [235-237]. Studies on the heat capacity of vicinal water and heavy water in the pores of silica gel and porous glasses have been reported, giving values 25% greater than that of bulk water [238-241]. 

It is weU known, of course, that water pours rather freely despite the rather strong inter-molecular H-bonding. The viscosity of water at 298.15 K is 0.8903 cP, much smaller than that of glycerol (954 cP). The difference in viscosity between normal and heavy water is noticeable. Overall, the bulk transport properties appear to look rather normal, but, as noted by Franks, the simple numbers hide a complexbehavior that is revealed by the temperature and pressure dependence of the transport properties. 

Another quantity of interest is the ionic viscosity -coefficient. Equation 2.29, that in aqueous solutions describes the effect of the ion on the structure of the solvent water. Some values of in nonaqueous solvents have been compiled by Jenkins and Marcus [9] and are reproduced in Table 5.7. It should be noted that practically in all the solvents (except light and heavy water), all the Brj values are positive and the ions appear to enhance the structure of the solvent. However, the splitting of the... 

Viscosity and thermal conductivity of heavy water substance... 

The viscosity and thermal conductivity of heavy water and steam, the heavy water substance D2O, show trends which are similar to those of ordinary water substance. 

Formulations for general and sdentiflc use have also been adopted for other properties of water. The most industrially important of these are probably the viscosity and the thermal conductivity, although some other properties such as the static dielectric constant and the refractive index are important in research. There are also lAPWS formulations for some properties of heavy water (deuterium oxide, D2O). 

Viscosity of D2O and uranium solutions. The viscosity of heavy water was measured from 30 to 250°C by Heiks et al. [54]. Good agreement with four values reported by Hardy and Cottington [65] was found. The apparatus used has been described by Heiks et al. [51] and the electronic instrumentation for measuring the time of fall of a plummet containing a radioactive pellet has been described by Rogers et al. [52]. 

Van Winkle [57] discussed the viscosity of light and heavy water and the early data for solutions of uranyl sulfate in heavy water. 

Heiks and Jegart of Mound Laboratory [50,56] measured the viscosity of uranyl sulfate solutions in light water over a concentration range of 0.176 to 2.865 molal and over a temperature range of 20 to 90°C by the use of Ostwald capillary viscometers. Using the falling-body viscometer referred to above, Barnett et al. of Mound Laboratory have measured the viscosities of light- and heavy-water solutions of uranyl sulfate at temperatures up to 250°C [55]. Table 3-9 presents a comparison of viscosities... 

Viscosities of Light- and Heavy-Water Solutions of Uranyl Sulfate... 

M. K. Barnett et al.. The Density, Viscosity, and Surface Tension of Light and Heavy Water Solutions of Uranyl Sulfate at Temperatures to 2B0°C, USAEC Report MLM-1021, Mound Laboratory, Dec. 6, 1954. 

Source hitematicm AssociaticmforthePropeilies of Water Steam, Viscosity of Thenn Conductivity of Heavy Water Substance in Physical Chemistry of Aqueous Systems Proceedings of the 12th Internaticm Cwiference on die Properties of Water and Steam, Orlando, FL, 1994, 07—aI38. 

Viscosity of water phase, when oil droplets are rising through heavy water phase... 

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