Constants, chemical

Timmermans, J. "Physical-Chemical Constants of Pure Organic Compounds," Vol. 1-2, Elsevier, Amsterdam, 1950-65. 

Timmermans, J. "The Physico-Chemical Constants of Binary Systems in Concentrated Solutions," Vol. 1-4, Interscience, New York, 1959-60. 

Technical data, "Typical Composition and Chemical Constants of Common Edible Eats and Oils", Durkee Industrial Eoods, 1992. 

Table 1. Physical and Chemical Constants of Fluorosulfuric Acid...

J. Timmermans Phjsico-Chemical Constants of Pure Organic Compounds Elsevier Publishiag Co., Inc., New York, 1950. 

J. Timmermans, Physico-Chemical Constants of Pure Organic Substances, 2nd ed., 2 vols., Elsevier, New York, 1965. 

H. Stephen and T. Stephen, Solubilities of Inorganic and Organic Compounds Vol. 1, Parts 1 and 2, Macmillan Publishing, New York, 1963. J. Timmermans, Phjsico-Chemical Constants of Pure Organic Compounds Vol. 2, Elsevier Science Publishing Co., Inc., New York, 1965. 

A summary of physical and chemical constants for beryUium is compUed ia Table 1 (3—7). One of the more important characteristics of beryUium is its pronounced anisotropy resulting from the close-packed hexagonal crystal stmcture. This factor must be considered for any property that is known or suspected to be stmcture sensitive. As an example, the thermal expansion coefficient at 273 K of siagle-crystal beryUium was measured (8) as 10.6 x 10 paraUel to the i -axis and 7.7 x 10 paraUel to the i -axis. The actual expansion of polycrystalline metal then becomes a function of the degree of preferred orientation present and the direction of measurement ia wrought beryUium. 

Pure biphenyl is a white crystalline soHd that separates from solvents as plates or monoclinic prismatic crystals. Commercial samples are often slightly yellow or tan in color. Similady, pure terphenyls are white crystalline soHds whereas commercial grades are somewhat yellow or tan. Physical and chemical constants for biphenyl and the three isomeric terphenyls are given in Tables 2 and 3, respectively. 

Other early tabulations of numerical data were the French Tables Annuelles de Constantes et Donnees Numeriques which appeared for some decades after 1920, and the British Tables of Physical and Chemical Constants, masterminded by the National Physical Laboratory and known affectionately as Kaye and Laby after the editors, which appeared annually in single volume form from 1911 to 1966. These last two, like Landolt-Bdrnstein, appeared regularly, in successive editions. 

The magnitude co, depending only on the specific chemical composition of the vapour, may be referred to as the primitive chemical constant p and i are derived chemical constants. 

The chemical constants may therefore be determined directly by the measurement of vapour pressures, especially at low temperatures. Equation (9), which is more general, shows that the chemical constant is determined for a. homogeneous gas as soon as we know A, and C, as functions of temperature, and the vapour pressure at one temperature. These data, especially vapour pressures at very low temperatures, are not very well known at present, and some other method must therefore be used in the determination of the chemical constant. Several such methods have been proposed by Nernst (loc. cit. cf. also Haber, Thermodynamics of Technical Gas Reactions, pp. 88—96 Weinstein, Thermodynamik and Kinetik III., 2, pp. 1064—1074). 

The values of i calculated from (8) and (8) do not agree very closely, and it would appear, as Weinstein (loc. cit. 1068) remarks, that Although the calculations undoubtedly establish the legitimacy of the system of equations, the great uncertainty in the numerical determination of the decisive magnitudes forms a practical defect which will only be removed by observations over very wide intervals of the variables. Any discrepancy between the results of actual observations of equilibria, and those calculated by means of Nernst s chemical constants, need not, in the present state of uncertainty of the latter, cause any great alarm. Nernst himself apparently regards the constant < >, obtained from vapour-pressure measurements, as the most certain, and the others as more or less tentative. 

The vapour-pressure equation (22) has been verified for brom-and iodo-naphthalene by L. Rollo(7) (1909), and for toluene, naphthalene, and benzene by J. T. Barker (1910). The latter finds that the solid and liquid states give the same chemical constant, which is in agreement with Nemst s theory. 

If we compare (8) with equation (2) of 148, putting const. = il in the latter, we see that the indeterminate constant of the equilibrium equation is now completely determined as the sum of the chemical constants of the interacting gases ... 

The table of chemical constants given by Nernst (Berl. Bcr. 1909, p. 247) is ... 

A very interesting calculation has been carried out by N. Bjerrum (Zeitschr. Elektrocliem., 1911 Nernst Festschrift, 1912) in which the rotational energy is connected with the frequencies of the infra-red absorption bands of a gas. The chemical constants of gases have also recently been calculated from kinetic principles by Sackur (Nernst Festschrift, 405, 1912 Ann. Phijs., 40, 67, 84, 1918). 

Page 502, table of chemical constants. In the most recent publication (Theoretische Chemie, 7th edit., 1913) Nernst has changed the values slightly in some cases ... 

Solvent extraction is often applied to separate two chemically similar metals such as nickel/ cobalt, adjacent rare earths, niobium/tantalum, zirconium/hafnium, etc. For the purpose of elaboration, the example of the separation of two chemically similar elements such as zirconium and hafnium from their nitrate solution, using TBP as an extractant is considered. The solvent extraction process in this case is chemically constant (K) is given by ... 

Continuous analysis offers another very useful possibility of completely automated chemical control, especially in manufacturing processes, but also in analytical processes such as separational flow techniques where the analytical measurement proper acts as a sensor, usually called the detector. As long as a physical or physico-chemical constant yields a sufficiently accurate and specific... 

Timmermanns, J. (1950) Physico-chemical Constants of Pure Organic Compounds (Elsevier). 

Kaye and Laby tables of physical and chemical constants http //www.kayelaby.npl.co.uk/chemistry/... 

Redgrove, H. Stanley. 1909. On the Calculation of Thermo-Chemical Constants. London n.p. 

G. W. C. Kaye and T. H. Laby, Tables of Physical and Chemical Constants, Longman 1995, gives a table of properties of the nuclides including isotopic abundance or half-life, decay modes, mass excess, neutron capture cross-section and ground-state spin and parity. This publication, with a prospect of regular updates, is available on the website http //www.kayelaby.npl.co.uk/. 

We have so far succeeded in establishing connections between surface tension and a number of physical properties, but have not yet found a relation between the former and any chemical constant. A very simple and general relation of this kind was first pointed out by the Hungarian physicist Eotvos and confirmed experimentally, for a large number of liquids, by Ramsay and Shields. If M is the molecular weight of a liquid and p its density, then... 

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