Absorption of nitric acid

The absorption of nitric acid vapor at 1.4u has been measured so that the equilibrium represented by Eq 5 could be studied H20(g) + 2N02(g) + l/203(g) 2HN03(g) (5)... 

The absorption of nitric acid is a phenomenon preceding nitration. Afterwards nitric acid is also absorbed by the nitrocellulose formed. This phenomenon has been examined under various conditions e.g. the absorption of nitric acid in vapour form and the absorption of HN03 from pure nitric acid and from its solution respectively. 

Wilson and Miles [12] have measured the absorption of nitric acid by treating with it nitrocotton of 13.8% N. Under a pressure of 4 mm Hg as much as 15% of HN03, was absorbed by this nitrocotton. Nitric acid is absorbed better by a lowernitrated substance, just as the absorption of water vapour is easier in the case of lower-nitrated nitrocellulose. The maximum absorption has been established with nitrocellulose of 7% N. The amount of nitric acid absorbed by cellulose depends on its type. For native cellulose it amounts to about 25% by weight of the cellulose, and approaches 50% for mercerized cellulose. Such differences in the behaviour of different kinds of nitrocellulose indicates that swelling has an appreciable influence on absorption. Mercerized cotton which is more liable to swell simultaneously shows stronger absorption. 

The absorption of nitric acid from the nitrating mixtures is exceptionally interesting and important from the theoretical and practical point of view. It has long been known that nitric acid absorbed from a mixed acid is richer in HN03 than the nitrating acid itself. 

The product of absorption of nitric acid vapours by cellulose is according to Wilson not a Knecht compound, since it did not give the characteristic X-ray diagram although its chemical composition is approximately that of the Knecht compound. 

Absorption of nitric acid by cellulose and nitrocellulose Nitration with mixtures of nitric and sulphuric acids... 

Fog water at locations in the Eastern U.S. (data from Whiteface Mountain [Arons et al., 1988] are shown in Figure 10 for comparison) and in Europe tends to contain less nitrate than in California, but a much higher proportion of nitrate is seen in fog than is typically found in aerosol at the same locations, because of the absorption of nitric acid (vapor). 

The Raman spectrum of nitric acid shows two weak bands at 1050 and 1400 cm. By comparison with the spectra of isolated nitronium salts ( 2.3.1), these bonds were attributed to the nitrate and nitronium ion respectively. Solutions of dinitrogen pentoxide in nitric acid show these bands , but not those characteristic of the covalent anhydride , indicating that the self-dehydration of nitric acid does not lead to molecular dinitrogen pentoxide. Later work on the Raman spectrum indicates that at —15 °C the concentrations of nitrate and nitronium ion are 0-37 mol 1 and 0 34 mol 1 , respectively. The infra-red spectrum of nitric acid shows absorption bands characteristic of the nitronium ion. The equivalence of the concentrations of nitronium and nitrate ions argues against the importance of the following equilibrium ... 

The two absorption bands, at 1050 and 1400 cm , which appear in the Raman spectra of solutions of nitric acid in concentrated sulphuric acid are not attributable to either of the acid molecules. In oleum the lower band appears at 1075-1095 cm. That these bands seemed to correspond to those in the spectra of anhydrous nitric acid and solid dinitrogen pentoxide caused some confusion in the assignment of the spectrum. The situation was resolved by examining the Raman spectra of solutions of nitric acid in perchloric or selenic acids , in which the strong absorption at 1400 cm is not accompanied by absorption at about 1050 cm . Thus, the band at 1400 cm arises from the nitronium ion, and the band at about 1050 cm can be attributed in the cases of nitric acid and solid dinitrogen pentoxide to the nitrate ion formed according to the following schemes ... 

THE STATE OF NITRIC ACID IN INERT ORGANIC SOLVENTS The absence of ions in mixtures of acetic acid and nitric acid is shown by their poor electrical conductivity and the Raman spectra of solutions in acetic acid, nitromethane, and chloroform show only the absorptions of the solvent and molecular nitric acid the bands corresponding to the nitronium and nitrate ions cannot be detected. -... 

An investigation of the infra-red spectra of mixtures of nitric acid and acetic anhydride supports these conclusions. The concentration of nitronium ions, measured by the absorption band at 2380 cm, was... 

Synthetic Sodium Nitrate. Sodium nitrate can be synthetically obtained by absorption of nitrous gases or by neutralization of nitric acid... 

Sodium hypochlorite hy action of chlorine on aqueous sodium hydroxide Ammonium nitrate hy action of ammonia on aqueous nitric acid Nitric acid hy absorption of nitric oxide in water... 

Theoretically, to produce 1 kg of nitric acid requires at least 0.27 kg of ammonia and 4.33 kg of air (or 1.02 kg of oxygen). These weights refer to the content of concentrated acid. Realistically, however, the process is divided into three successive stages combustion, oxidation, and absorption. 

An initial solution was prepared by dissolving metallic niobium powder in 40% hydrofluoric acid. The dissolution was performed at elevated temperature with the addition of a small amount of nitric acid, HN03, to accelerate the process. The completeness of niobium oxidation was verified by UV absorption spectroscopy [21]. The prepared solution was evaporated to obtain a small amount of precipitate, which was separated from the solution by filtration. A saturated solution, containing Nb - 7.01 mol/1, HF - 42.63 mol/1, and corresponding to a molar ratio F Nb = 6.08, was prepared by the above method. The density of the solution at ambient temperature was p = 2.0 g/cc. Concentrations needed for the measurements were obtained by diluting the saturated solution with water or hydrofluoric acid. 

Absorption of Nitrogen Oxides in Water to Form Nitric Acid Solution. The production of nitric acid from nitrous gases such as are obtained in... 

Fox, D. L L. Stockburger, W. Weathers, C. W. Spicer, G. I. Mackay, H. I. Schiff, D. J. Eatough, F. Mortensen, L. D. Hansen, P. B. Shepson, T. E. Kleindienst, and E. O. Edney, Intercomparison of Nitric Acid Diffusion Denuder Methods with Tunable Diode Laser Absorption Spectroscopy, Atmos. Environ., 22, 575-585 (1988). 

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