Temperature of maximum density

D2O and the tritium analogue T2O (p. 41). The high bp is notable (cf. H2S, etc.) as is the temperature of maximum density and its marked dependence on the isotopic composition of water. The high dielectric constant and measurable ionic dissociation equilibrium are also unusual and important properties. The ionic mobilities of [H30] and [OH] in water are abnormally high (350 X 10 " and 192 x 10 cms per V cm... 

The freezing point, temperature of maximum density, osmotic pressure and specific heat for seawater of various salinities are given in Table 21.23. 

Salinity Freezing point (°C) Temperature of maximum density Osmotic pressure (atm) Specific heat (J kg- )... 

For scientific purposes the convenient unit to employ for measuring reasonably large volumes of liquids is the cubic decimetre (dm3), or, for smaller volumes, the cubic centimetre (cm3). For many years the fundamental unit employed was the litre, based upon the volume occupied by one kilogram of water at 4 °C (the temperature of maximum density of water) the relationship between the litre... 

Litre—is defined as the volume occupied hy one kilogram of water at its temperature of maximum density (4°C) and subjected to normal atmospheric pressure . The litre is considered as the standard unit of volume for all volumetric measurements. 

Thermal expansion Temperature of maximum density decreases with increasing salinity for pure water it is at 4°C Fresh water and dilute seawater have their maximum density at temperatures above the freezing point this property plays an important part in controlling temperature distribution and vertical circulation in iakes... 

Between 0 °C and the temperature of maximum density (4 °C) the hydrogen bond collapse dominates over the normal thermal expansion. At temperatures above that of the maximum density, thermal expansion dominates, and the density decreases progressively as the temperature rises. 

In spite of numerous studies, the properties of liquid water are still far from been understood at a molecular level. For instance, large isotope effects are seen in some properties, such as the temperature of maximum density, which occur at 277.2 K in liquid H20 and 284.4 K in D20. The isotope shift 7.4 K will be used below with the purpose to employ the Liebe et. al. formula [17] for calculation of the low-frequency dielectric permittivity of D20 in analogous way as it used for H20. 

W.L. Jorgensen, C. Jenson, Temperature dependence of TIP3P, SPC, and TIP4P water from NPT Monte Carlo simulations Seeking temperatures of maximum density. J. Comput. Chem. 19, 1179 (1998)... 

Temperature of maximum density decreases with increasing salinity for pure water it is at 4°C Highest of all liquids... 

Most systems expand by about 10% on going from the solid to liquid states, the expansion resulting from a decrease in co-ordination number rather than from a change in nearest neighbour distances. In contrast, the transition, ice to water, is accompanied by a decrease in molar volume and an increase in density of about 10%. Moreover, on raising the temperature, the volume decreases passing through a minimum near 277 K, the temperature of maximum density (TMD) subsequent increase in temperature results in an increase in volume... 

On the hydrogen scale, according to the most reliable data, namely those of Chapprus, Travaux Mem. Bureau intemat. Poids et Mesures, 1904,13,40 and of Thiesen, Scheel, and Diesselhorst, IVt.ss. Abhandl Physiledlisch-Tech. Reichanstalt, 1900,3,68. Numerous other determinations have been made of the temperature of maximum density, the results ranging from 2 22° C (Dalton) to 4-08° G. (Kopp) The more important of these data are as follow ... 

Increase of pressure reduces the temperature of maximum density 2 the two factors being connected by the expression... 

Figure 2 The temperature of maximum density (—) and freezing point (- -) of seawater as a function of dissolved salt content (Adapted from Tchernia, 1980. )...

Transferability from the solid state to the liquid state is equally problematic. A truly transferable potential in this region of the phase diagram must reproduce not only the freezing point, but also the temperature of maximum density and the relative stability of the various phases of ice. This goal remains out of reach at present, and few existing models demonstrate acceptable transferability from solid to liquid phases.One feature of water that has been demonstrated by both an EE model study and an ab initio study °° is that the dipole moments of the liquid and the solid are different, so polarization is likely to be important for an accurate reproduction of both phases. In addition, while many nonpolarizable water models exhibit a computed temperature of maximum density for the liquid, the temperature is not near the experimental value of 277 Eor example, TIP4P and... 

Dependence of TIP3P, SPC, and TIP4P Water from NPT Monte Carlo Simulations Seeking Temperatures of Maximum Density. 

AGt°(i)e = component of AGt°(i) arising from the charge on i x2 = mole fraction of co-solvent vol2 = partial molar volume of the co-solvent molecule TE = structural contribution to the temperature of maximum density... 

Critical temperature (°C) Critical pressure (atm) Temperature of maximum density of liquid (°C) Maximum density of liquid (gcm )... 

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