Hydration mass ratio

BALLPARK Check If the hydrate contained 1 mol of H20 per mole of CaCr04, the mass ratio of H20 to CaCr04 would be 18 g/mol divided by 156 g/mol, or about 0.1. The actual mass ratio of H20 to CaCr04 in the hydrate is approximately (1.8-1.5) g/1.5g = 0.2, so the hydrate must contain 2 mol of H20 per mole of CaCr04. The ballpark check agrees with the solution. 

There are comparatively few measurements of the hydrate phase composition, due to experimental difficulty. Hydrate phase difficulties arise because water is often occluded in the hydrate mass, separation of hydrate and water is difficult, and the hydrate phase of mixtures is often inhomogeneous in experiments. Consequently, the ratio of water to hydrocarbon is often inaccurate. As discussed in Chapter 6, only over the last two decades have experimental techniques (e.g., diffraction and NMR and Raman spectroscopy) become accurate enough to determine the degree of filling of hydrate cavities with different types of molecules. 

To prevent water occlusion. Without agitation, Villard (1896) showed, for example, that nitrous oxide hydrate formation was continuous for a period longer than 15 days under a pressure of 2 MPa. Villard also determined that in previous research the ratio of water to guest molecules had been analyzed as greater than G 6H20 (Villard s Rule) due to either occlusion of water within the hydrate mass, or due to the loss of the guest component. 

The first way is pipeline transport of concentrated coal-water slurry. It assumes that utilisation of coal particle distribution preparation and/or using the various additives can substantially increase mass concentration of coal-water slurry till 70-80 %. For example, Black Messa Pipeline realised in USA transports 4.8 million tons of coal per year over the distance 439 km from the colliery in North Arizona to power plant Mohave near the border of Nevada and California with mass ratio of coal to water about 1 1, without using any additives, [5]. Recently, in the USA, Italy, China, Russia and other countries several coal pipelines were already realised. Even Oil and gas should be effectively transported as hydrate slurries, [6],... 

Viscosity studies have also been carried out to investigate the effect of the surfactant and cosurfactant concentrations as well as the surfactant-cosurfactant mass ratio on the hydration of the disperse-phase droplets for o/w ME systems [58], A... 

Several deuterium isotopic effects are found in solid hydrates, additionally to the frequency shifts on deuteration due to the mass ratio (earlier discussed. Sects. 4.2.6, 4.3, 4.4, 4.5). These isotopic effects are caused by the different vibrational zero point energies, the different tunnelling probabilities, and the differently strong H-bonds of hydrates and deuterohydrates, i.e, stronger bonds for OH A than for OD A interactions . ... 

Figure 5.32. A. Al NMR spectra of (top) unhydrated alumina cement (principally monocalcium aluminate), and (bottom) product of full hydration with demineralised water at a cement water mass ratio of 1 1. Asterisks indicate spinning side bands. B. Change in the percentage of four-coordinated Al in alumina cement during hydration, as a function of time estimated by Al MAS NMR. Open symbols (a) hydration with demineralised water. Filled symbols (b) hydration with 0.5 mass percent Li2C03 solution. After Luong et al. (1989), by permission of the American Ceramic Society.

Figure 3 Distribution of pore sizes of an hydrated Portland cement paste 4 months old (initial mass ratio water/cement of 0.4) obtained by mercury intrusion. The pore family related to the calcium silicate hydrate (some nm) and that of capillary porosity (a few hundreds ofnm) can be easily distinguished. The finest porosity is completely saturated with interstitial liquid while the capillary porosity is partially.

Thus, the intrinsic viscosity of solvated spheres depends on the partial specific volume V2 of the solute, the specific volume vi of water, and the mass ratio r = mP/mi (degree of solvation) of both components in the interior of the sphere. Therefore, it is not possible to calculate the molar mass of a solvated sphere from the intrinsic viscosity alone. The intrinsic viscosities of spherical protein molecules are low, and for equal degrees of hydration are independent of the molar mass (Table 9-6). Admittedly, the proteins included in Table 9-6 are not perfectly spherical, since their coefficients of friction / are somewhat larger than those expected for a perfect sphere, o. 

Another option is to obtain, at an approximately constant temperature, the precipitation of the crystals by increasing the solute concentration above the solubility threshold. To obtain this, the solute/solvent mass ratio is increased using the technique of evaporation. This process is of course insensitive to change in temperature (as long as hydration state remains unchanged). 

We shall see in Sec. 9.10 that sedimentation and diffusion data yield experimental friction factors which may also be described-by the ratio of the experimental f to fQ, the friction factor of a sphere of the same mass-as contours in solvation-ellipticity plots. The two different kinds of contours differ in detailed shape, as illustrated in Fig. 9.4b, so the location at which they cross provides the desired characterization. For the hypothetical system shown in Fig. 9.4b, the axial ratio is about 2.5 and the protein is hydrated to the extent of about 1.0 g water (g polymer)". ... 

In August 2006, the International Astronomical Union redefined the term planet and decided that the former ninth planet in the solar system should be referred to as a dwarf planet with the number 134340. The dwarf planet Pluto and its moon, Charon, are the brightest heavenly bodies in the Kuiper belt (Young, 2000). The ratio of the mass of the planet to that of its moon is 11 1, so the two can almost be considered as a double planet system. They are, however, quite disparate in their composition while Pluto consists of about 75% rocky material and 25% ice, Charon probably contains only water ice with a small amount of rocky material. The ice on Pluto is probably made up mainly of N2 ice with some CH4 ice and traces of NH3 ice. The fact that Pluto and Charon are quite similar in some respects may indicate that they have a common origin. Brown and Calvin (2000), as well as others, were able to obtain separate spectra of the dwarf planet and its moon, although the distance between the two is only about 19,000 kilometres. Crystalline water and ammonia ice were identified on Charon it seems likely that ammonia hydrates are present. 

The ratio of the molecular mass of the hydrate to that of the anhydrous salt,... 

A simple calculation reveals the limits of the numbers of water molecules that may be associated with an ion in a standard solution. A l mol dm-3 aqueous solution of sodium chloride has a density of 1038 kg m-3 at 25 °C, so 1 dm3 of such a solution has a mass of 1038 g. One mole of the salt has a mass of 58.44 g, so the water in the litre of solution has a mass of 1038-58.44 = 979.56 g. This amount of water contains 979.56/18.015 = 54.4 moles of the liquid. The molar ratio of water molecules to ions in the 1 mol dm-3 aqueous solution of Na h(aq) and Cl (aq) ions is therefore 54.4/2 = 27.2, assuming that the water molecules are shared equally between the cations and anions. This represents the theoretical upper limit of hydration of any one ion in a standard solution of 1 mol dm-3 concentration. The limit may be exceeded in more dilute solutions, but that depends upon the operation of forces over a relatively long range. Certainly, in more concentrated solutions, the limits of hydration of ions become more restricted as fewer water molecules are available to share out between the cation and anion assembly. 

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