Temperature dependent solubility

The temperature dependences of the Henry s Law coefficients of the different gases listed in Table 3.6 are quite variable (Fig. 3.11). Helium, the least soluble noble gas, has very little solubility temperature dependence between 0 and 30 °C. On the other hand, Kr, the second most soluble of the non-radioactive noble gases, is much less soluble at higher temperatures. More details about gas solubilities are presented in the chapter on air-sea gas exchange (Chapter 10). Another notable aspect of the temperature dependence of the gas solubilities is that they are not linear. Thus, mixing between parcels of water of different temperatures at saturation equilibrium with the atmosphere results in a mixture that is supersaturated. This effect has been observed for noble gases in the ocean and may ultimately have a utility as a tracer of mixing across density horizons. 

R. Prankerd and R. McKeown, Physico-chemical properties of barbituric acid derivatives. Part 1. Solubility-temperature dependence for 5,5-disubstituted barbituric acids in aqueous solutions, Int.. Pharm., 1990,62(1), 37-52. 

R. Prankerd, Solid state properties of drugs. Part I. Estimation of heat capacities for fusion and thermodjmamic functions for solution from aqueous solubility-temperature dependence measurements, Int. J. Pharm., 1992,84(3), 233-244. 

Christophers SR, Dissociation constants and solubilities of bases of anti-malarial compoimds. 1. Quinine. II. Atebrin, Ann. Trop. Med. Parasitol. 31,43-69 (1937). CA 31 58602. Cited in Perrin Bases no. 2958 ref. C30. NB This paper reported pKb values of 5.70 (equivalent to pXa = 8.47) and 9.85 (equivalent to pK = 4.32), using pKyf = 14.167 at 20 °C. These do not corre ond exactly wid the values quoted by Perrin. Also reported die solubility-temperature dependence. 

CHEOPS is based on the method of atomic constants, which uses atom contributions and an anharmonic oscillator model. Unlike other similar programs, this allows the prediction of polymer network and copolymer properties. A list of 39 properties could be computed. These include permeability, solubility, thermodynamic, microscopic, physical and optical properties. It also predicts the temperature dependence of some of the properties. The program supports common organic functionality as well as halides. As, B, P, Pb, S, Si, and Sn. Files can be saved with individual structures or a database of structures. 

The concentration of dissolved ionic substances can be roughly estimated by multiplying the specific conductance by an empirical factor of 0.55—0.9, depending on temperature and soluble components. Since specific conductance is temperature dependent, all samples should be measured at the same temperature. Alternatively, an appropriate temperature-correction factor obtained by comparisons with known concentrations of potassium chloride may be used. Instmments are available that automatically correct conductance measurements for different temperatures. 

Solubility of Ba(OH)2 in water is strongly temperature dependent in the range >40 C. 

The temperature dependence of the permeability arises from the temperature dependencies of the diffusion coefficient and the solubility coefficient. Equations 13 and 14 express these dependencies where and are constants, is the activation energy for diffusion, and is the heat of solution... 

Another factor in this reaction sequence is also subject to external modification, namely, moderation of the basic oceanic dissolution of CO2 through temperature dependence of its solubility, S. The latter is defined as ... 

In addition, the temperature dependence of the diffusion potentials and the temperature dependence of the reference electrode potential itself must be considered. Also, the temperature dependence of the solubility of metal salts is important in Eq. (2-29). For these reasons reference electrodes with constant salt concentration are sometimes preferred to those with saturated solutions. For practical reasons, reference electrodes are often situated outside the system under investigation at room temperature and connected with the medium via a salt bridge in which pressure and temperature differences can be neglected. This is the case for all data on potentials given in this handbook unless otherwise stated. 

Solubility parameters are generally tabulated, together with the corresponding liquid molar volumes, only at 25°C. Although solubility parameters are themselves temperature-dependent, the combination of quantities in Eq. 70 is not. Differentiating Eq. 70 with respect to temperature gives — the excess entropy, a quantity which has been assumed to be zero in accord with the definition of a regular solution. Thus only data at 25°C are needed. Solubility parameters may be... 

The shape of the equilibrium line, or solubility curve, is important in determining the mode of crystallization to be employed in order to crystallize a particular substance. If the curve is steep, i.e. the substance exhibits a strong temperature dependence of solubility (e.g. many salts and organic substances), then a cooling crystallization might be suitable. But if the metastable zone is wide (e.g. sucrose solutions), addition of seed crystal might be necessary. This can be desirable, particularly if a uniformly sized product is required. If on the other hand, the equilibrium line is relatively flat (e.g. for aqueous common salt... 

Temperature-dependent phase behavior was first applied to separate products from an ionic liquid/catalyst solution by de Souza and Dupont in the telomerization of butadiene and water [34]. This concept is especially attractive if one of the substrates shows limited solubility in the ionic liquid solvent. 

In the absence of sufficient hydrogen, the solubility of magnetite is markedly temperature dependent, which provides an explanation for some of the problems in high-temperature circuits. Most studies in boilers relate to high temperatures. Thus the work of Bloom " and of Potter and Mann has reproduced the types of corrosion found in high-pressure boilers. The relationship between corrosion rates and iron solubility and pH are given in Fig. 17.2. Note that the pH range about the neutral point (relative to 300 C... 

Vapor pressure, like density and solubility, is an intensive physical property that is characteristic of a particular substance. The vapor pressure of water at 25°C is 23.76 mm Hg, independent of volume or the presence of another gas. Like density and solubility, vapor pressure varies with temperature for water it is 55.3 mm Hg at 40°C, 233.7 mm Hg at 70°C, and 760.0 mm Hg at 100°C. We will have more to say in Chapter 9 about the temperature dependence of vapor pressure. 

The temperature dependence of the activity coefficients is assumed to have a particularly simple form, and this can sometimes lead to serious error at temperatures far away from those used to evaluate the solubility parameters. 

Krafft temperatures depend not only on chain length but on the cation. Eth-oxylation of the base alcohol reduces the Krafft temperature due to the higher solubility of the sulfate. Calcium and other earth alkaline metals produce an increase of the Krafft temperature that is significantly reduced by ethoxylation of the alcohol. The decrease is more significant for alkaline earth metals than for alkaline cations as shown in Table 6 [81,82], although it should be noted that, according to other workers, sodium dodecyl sulfate has a Krafft temperature of 16°C. 

Atmospheric Reaeration. Interfacial properties and phenomena that govern oxygen concentrations in river systems include 1) oxygen solubility (temperature, partial pressure and surface dependency), 2) rate of dissolution of oxygen (saturation level, temperature and surface thin film dependency, i.e., ice, wind), and 3) transport of oxygen via mixing and molecular diffusion. A number of field and empirically derived mathematical relationships have been developed to describe these processes and phenomena, the most common of which is (32) ... 

The sodium and potassium salts are veiy soluble in water but they are hydrolysed in solution, at a temperature-dependent rate, to the corresponding penicilloic acid (Fig. 5.3 A see also Fig. 9.3), which is not antibacterial. Penicilloic acid is produced at alkaline pH or (via penieillenic acid Fig. 5.3B) at neutral pH, but at acid pH a molecular rearrangement oeeurs, giving penillic acid (Fig. 5.3C). Instability in acid medium logically precludes oral administration, since the antibiotic may be destroyed in the stomach for example at pH 1.3 and 35°C methicillin has a half-life of only 2-3 minutes and is therefore not administered orally, whereas ampicillin, with a half-life of 600 minutes, is obviously suitable for oral use. 

However, usually the solubility increases with higher temperature. The temperature coefficent of solubility is dependent on the enthalpy of dissolution. An exothermic enthalpy of dissolution causes a decrease in solubility with increased temperature, and vice versa. 

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