Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Affinity Ostwald

Wilhelm Ostwald, Elektrochemie (1896). See the discussion in Barkan, "Walther Nernst," 4445. Ostwald s first chemical researches concerned chemical affinities from these studies he went on to investigate electrolytic dissociation, electrical conductivity, mass action, reaction velocities, and catalysis. It was for work on catalysis that he was awarded the Nobel Prize in chemistry in 1909. [Pg.158]

For chemists, the problem of affinity, or what Meyer called variable valence, was the central problem of chemistry, one in which, Ostwald claimed, chemists made no progress while seeking to measure chemical "forces." Meyer, who often is identified with the tradition of physical chemistry and theoretical chemistry, as noted in chapter 3, was confident that the answer to affinity lay in theories of motion, not in species or types, just as Nemst later was to identify the end of affinity theory with its reduction to physical causes. [Pg.291]

The inhalational anesthetics have distinctly different solubility (affinity) characteristics in blood as well as in other tissues. These solubility differences are usually expressed as coefficients and indicate the number of volumes of a particular agent distributed in one phase, as compared with another, when the partial pressure is at equilibrium (Table 25.3). For example, isoflurane has a blood-to-gas partition coefficient (often referred to as the Ostwald solubility coefficient) of approximately 1.4. Thus, when the partial pressure has reached equilibrium, blood will contain 1.4 times as much isoflurane as an equal volume of alveolar air. The volume of the various anesthetics required to saturate blood is similar to that needed to saturate other body tissues (Table 25.3) that is, the blood-tissue partition coefficient is usually not more than 4 (that of adipose tissue is higher). [Pg.301]

Berzelius introduced the term catalysis as early as 1836 to explain various decomposition and transformation reactions. He later referred to the special power that some substances (catalysts) have for influencing the affinity of chemical substances. According to the Ostwald definition of catalyst (1895), it was assumed that the catalyst remained unchanged in the course of the reaction but now it is known that it is involved in chemical bonding with the reactants during the catalytic cycle. Thus, catalysis is a process in which the rate of a reaction is enhanced under... [Pg.429]

The electro-affinity of lithium is smaller than that of any of the other alkali metals, and it exhibits a greater tendency than the other alkali metals to form complex salts—e.g. the solubility of ammonia in water is raised by the addition of a lithium salt, which presumably unites with the ammonia the solubility curves of the lithium salts in water usually show more breaks than the corresponding salts of the other alkali metals owing to the formation of hydrates. Potassium, rubidium, and caesium seem to have a smaller and smaller tendency to form complex salts as the at. wt. of the element increases otherwise expressed, the electro-affinity, or the ionization tendency of the alkali metals increases as the at. wt. increases. This is illustrated by the heats of ionization. According to W. Ostwald,27 the heat of ionization per gram-atom iB... [Pg.460]

Unlike the results calculated for degrees of ionization from the depressions of the f.p., the values of Ostwald s constant computed from the electric conductivities of soln. of rubidium nitrate show marked deviations from constancy and they are thus constant with results with other strong electrolytes—the rubidium ion Rb and the N0V4on are among those with the greatest electro-affinities. The electrical conductivity of lithium nitrate is greater in methyl alcohdl than in water, but in... [Pg.819]

Excellent articles on the development of the theories of chemical affinity are in Eaoul Jagnaux, Ilistoire de la Chimie, Affinite Chimique, 189i, I, pp. 300-360 Wilhelm Ostwald, Lehrbuch der Allgcmcincn Chemic, 2te Auf-lage, 1896-1902, II, 2, Vcrwandtsehaftslehre, pp. 18-198 M. M. Pattison Muir, Chemical Theories and Laws, 1907. Chap. XIV, pp. 379-430. [Pg.510]

The chemical properties o orthophosphoric add.—W. Muller-Erzbach21 has discussed the affinity of the metals for phosphoric acid. J. Thomsen found the avidity of a mol. of phosphoric acid for one of sodium hydroxide to be a quarter of the value of that for hydrochloric acid. The affinity of phosphoric acid for the bases is greater than that of carbonic acid, boric acid, phosphorous acid, and hypophosphorous acid. The catalytic action of phosphoric acid on the reaction between bromic and hydriodic acids has been studied by W. Ostwald on the reaction between iodic and sulphurous acids, by R. Hopke and A. Purgotti and L. Zanichelli on hydrazine sulphate, N2H4.H2S04. According to W. Ostwald, the velocity constant for the inversion of cane sugar by phosphoric acid is 6-21 when the value for hydrochloric acid is 100 and J. Spohr showed that the presence of neutral salts at 25° retards, or at 40° completely suppresses,the activity of phosphoric acid. [Pg.962]

Throughout his career as a chemist Ostwald followed the general approach of applying physical measurements and mathematical reasoning to chemical issues. One of his major research topics was the chemical affinities of acids and bases. To that end, he studied the points of equilibria in reaction systems where two acids in an aqueous solution compete with each other for a reaction with one base and vice versa. Because chemical analysis would have changed the equilibria, he skillfully adapted the measurement of physical properties, such as volume, refractive index, and electrical conductivity, to that problem. From his extensive data he derived for each acid and base a characteristic affinity coefficient independent of the particular acid-base reactions. [Pg.907]

Clearly, the larger the ratio rjs, the larger the relative affinity of s for the two phases. Since we are interested in the relative affinities of various solutes towards water, we can choose a constant reference solvent a and measure the ratio % for various solutes. The simplest reference solvent is an ideal gas, for which AGf = 0 and rjs in (3.3.3) reduces to the Ostwald coefficient (3.2.1) ... [Pg.306]

Ostwald said this was the first statement of the law of mass action, that the strength of the chemical action is proportional to the concentration of the reacting substance . Wenzel gives no numerical results and it is uncertain if he made the experiments. Wenzel s conclusion was criticised by Kirwan tin and antimony are more rapidly attacked by nitric acid than lead or copper, which have a greater affinity for the acid. Guyton de Morveau and Murray also discussed Wenzel s assumption in detail and rejected it, the affinity being modified by cohesion, etc., and the velocities are not always in the order of the affinities. [Pg.576]


See other pages where Affinity Ostwald is mentioned: [Pg.907]    [Pg.209]    [Pg.907]    [Pg.209]    [Pg.25]    [Pg.25]    [Pg.649]    [Pg.177]    [Pg.138]    [Pg.285]    [Pg.314]    [Pg.1612]    [Pg.510]    [Pg.1279]    [Pg.621]    [Pg.1189]    [Pg.1109]    [Pg.53]    [Pg.154]    [Pg.161]    [Pg.171]    [Pg.1425]    [Pg.610]    [Pg.353]    [Pg.314]    [Pg.1109]    [Pg.268]    [Pg.285]    [Pg.908]    [Pg.1425]    [Pg.8]    [Pg.637]    [Pg.1832]    [Pg.3447]    [Pg.4866]    [Pg.6138]    [Pg.7254]    [Pg.110]    [Pg.210]   
See also in sourсe #XX -- [ Pg.140 ]




SEARCH



Ostwald

© 2024 chempedia.info