Densities and Molar Volumes

The density of a glass is a strong function of its composition. Density is also dependent to a lesser extent on the measurement temperature and the thermal history of the sample. Changes in morphology can have a 

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Table 14.2 Densities and molar volumes of liquid and solid O2...

Figure 2.1 Hexane and C02 at 25 °C as predicted by the PR-EOS (a) volumeexpansionofthe liquid phase with pressurization of C02 and (b) solvent mixture density and molar volume with pressurization of C02.

The importance of framework density and molar volume is evident also for large pore, mesoporous silica [33] and for AIPO4 polymorphs [34], Data for the latter are included in Figure 7.19. For mesoporous silica a transition from a regime where cages and pores affects the energetics to one in which the large pores act as inert diluent is reported. A further increase in pore diameter does not appear to increase the enthalpy of the compound [33], The similarity in enthalpy of many different structures shows that the synthesis of metastable microporous framework... 

The close packing of the molecules of a substance in the liquid state results in a density much higher than in the gaseous state and approaching that in the solid state. The density, p, is the mass per unit volume, and can be expressed as the ratio of the molar mass M to the molar volume V of a liquid. Table 2.1 lists the values of the properties M and V of representative liquids that are important in the field of solution chemistry and solvent extraction. The densities and molar volumes depend on the temperature, and the latter are given for 25°C. (For a discussion of industrial solvents, see Chapter 12.)... 

An empirical relationship between molar refraction, density, and molar volume, that applies to many liquids over a considerable range of temperatures is that of Eykiman ... 

TABLE 2-XVI Density and Molar Volume of H Bonded Compounds Compared to Nonassociated Substances of Similar Size ... 

Density and Molar Volume. It is to be expected that compounds with intermolecular H bonds would have higher densities (and lower molar volumes) than internzdly bonded isomers. Of course, a meaningful comparison can be made only if data are available for similar compounds at the same temperature and in the same physical state. Some data are presented in Table 5-XI. In each case the ortho- isomer has lower density than those of the meta- acaA para- isomers. Furthermore, the H bonded compounds are more dense than similar non-interacting substances, a point made earlier in Table 2-XVI. ... 

Palomar et al. have carried out continuum model calculations on B3LYP/6-31++G optimized geometries of the following cations [Cmim]+ with n = 1, 2,4, 6, 8 and the following anions [Cl]-, [BFJ-, [FeClJ-, [PF6] , [NTf2]", [MeSOJ-, [EtSOJ", [TfO]" in order to estimate density and molar volume [158], A satisfactory prediction of the data is found with the exception of the ion pairs containing [PF6]- and [BFJ- anions. 

Densities and Molar Volumes of Three Substances at Atmospheric Pressure... 

Non-ideality of the system leads to relative deviations of density and molar volume, as well as of other volumetric properties, having magnitude of about 1%. Flere, contraction and expansion of solutions are approximately equiprobable. In systems in conditions close to separation, considerable contraction is possible. Flowever, two component systems formed from the most common solvents, used in practical applications, form solutions far from separation at usual temperature range. 

Taking into account the linear density dependence on temperature in equations [9.33] and [9.34], it is possible to calculate values of density and molar volume at any given temperature. 

Refractive indices for the various complexes are given in Tables 23 (p. 78), 51 and 52. Tables 23 and 51 also contain details of measured densities and molar volumes. Information on vibrational spectral studies of thorium nitrato complexes will be found in [6, 8,18, 24, 26]. Selected infrared and Raman assignments are listed in Tables 53 and 54. 

Table 11.12 shows the densities and molar volumes for several common gases. Since the volume and, therefore, the density of a gas changes significantly with changes in temperature and pressure, all these values were measured for gases at 25 °C and 100 kPa atmosphere pressure. 

Table 11.12 Densities and molar volumes for selected common gases... 

Mechanical and Thermal Properties Density and Molar Volume... 

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