Ostwald method

Nitric acid can be prepared by several methods, but the primary method is by the oxidation of ammonia using the Ostwald method, which was named for Wilhelm Ostwald (1853-1932). The Ostwald method enabled the Germans to produce explosives in World War... 

The approximate constancy of the values may be attributed partly to the fact that the concentration of the free ions in the various solutions is very low, so that is close to unity, and partly to the fact that the Ostwald assumption a=A/Aop is probably fairly near to the truth under the same conditions of high dilution of the ions. In general, the Ostwald method gives reasonably satisfactory results for dilute solutions of weak electrolytes for which the dissociation constant is of the order 10 or less. 

Walker and Ostwald method The apparatus is as shown in figure (5). It consists of two bulbs containing a weighed amoimt of the solution under study and... 

How will you determine lowering of vapour pressure by Ostwald method ... 

Time of conversion by I/p part (Noyes—Ostwald method)... 

Calibration of Burettes.—Burettes are most simply calibrated by the Ostwald method with the help of a small pipette (generally 2 C.C.), the volume of which has been accurately determined (Fig. 3). The calibration pipette is attached to the burette in the manner shown in the figure (Fig. 4). 

The original Ostwald viscometer has been modified in many ways, and a number of different versions are on the market (Table 4) (21). Most are available with a wide choice of capillary diameters and therefore a number of viscosity ranges. A number of viscometers are described in ASTM D445, which also Hsts detailed recommendations on dimensions and methods of use. 

Servos gives a beautifully clear explanation of the subject-matter of physical chemistry, as Ostwald pursued it. Another excellent recent book on the evolution of physical chemistry, by Laidler (1993) is more guarded in its attempts at definition. He says that it can be defined as that part of chemistry that is done using the methods of physics, or that part of physics that is concerned with chemistry, i.e., with specific chemical substances , and goes on to say that it cannot be precisely defined, but that he can recognise it when he sees it Laidler s attempt at a definition is not entirely satisfactory, since Ostwald s objective was to get away from insights which were specific to individual substances and to attempt to establish laws which were general. 

The measurements were performed in an Ostwald Cannon-Fenske viscometer (No. J-627-25) using the method described by Silberberg and Klein Ci). This involves determining the time of flow as a function of the amount of liquid in the viscometer. Amounts between 7 and 8 g are chosen and the viscometer weighed to determine the exact amount. Buffer replacements were undertaken by dilution. 

The pursuit of chemical thermodynamics, especially its applications in solution chemistry and electrochemistry, resulted in the establishment of a distinct scientific discipline of physical chemistry by the so-called Ionists in the late nineteenth century. These practitioners defined their aim as "theoretical chemistry," bridging the domains of physics and chemistry. Ostwald contrasted the aims and methods of the new discipline with the practices of organic chemists, whom he characterized as powerful, hidebound, fact-mongering opponents of the young band of Ionists. 

Ostwald, and Arrhenius on the new Zeitschrift fur physikalische Chemie. Raoult s name was one of only three French scientists listed among twenty-one on the title page of the first issue. Thus, Raoult, who had no advanced pupils in the Sciences Faculty at Grenoble, counted Lespieau as his student. Lespieau, in turn, introduced the methods of "cryoscopy" and "ebullioscopy" into Parisian laboratories. At Raoult s request, he also wrote an article on Raoult s apparatus for the Paris Chemical Society. 22 And through Raoult, Lespieau became thoroughly familiar with the latest developments in physical chemistry in the 1880s and 1890s. 

Ostwald s method of estimating the ysi of liquid — solid interfaces is not popular at present. Consequently, only two relevant papers are reviewed here. 

Bebahani, Gh.R.R., Hogan, P., and Waghorne, W.E. Ostwald concentration coefficients of acetonitrile in aqueous mixed solvents a new, rapid method for measuring the solubilities of volatile solutes, J. Chem. Eng. Data, 47 (5) 1290-1292,2002. 

An analogy may be drawn between the phase behavior of weakly attractive monodisperse dispersions and that of conventional molecular systems provided coalescence and Ostwald ripening do not occur. The similarity arises from the common form of the pair potential, whose dominant feature in both cases is the presence of a shallow minimum. The equilibrium statistical mechanics of such systems have been extensively explored. As previously explained, the primary difficulty in predicting equilibrium phase behavior lies in the many-body interactions intrinsic to any condensed phase. Fortunately, the synthesis of several methods (integral equation approaches, perturbation theories, virial expansions, and computer simulations) now provides accurate predictions of thermodynamic properties and phase behavior of dense molecular fluids or colloidal fluids [1]. 

---