Nitric acid and nitrates

Using the literature data for the concentrations of the non-hydrated acid in the HN03-H20 system, its states in the HN03-H2S04-H20 system, and its partial vapour pressures, the applicability of Henry s law has been demonstrated to non-hydrated nitric acid in these systems.128 On the basis of a study129 of the systems HN03-H20-M(N03)n (MB+ = Na+, Cu2+, Be2+, U02+, La3+, Fe3+, or Al3+), the salting-out activity of the nitrates is characterized by the separation coefficient I described by  

A mass-spectroscopic investigation has been made of the vaporization of CsN03. Although CsN03 was not observed, peaks attributable to Cs2N03, 

Cs2N02, CsO+, and N02 were observed, and the enthalpy of vaporization of CsN03 was estimated to be 23.7 ( 1.0) kcal mor1 at a mean temperature of 770 K.133 

A review has been published of the equilibrium and transport properties of low-melting mixed metal nitrates (e.g. NaN03 and AgN03).141 

Thermodynamic and other experimental data have been taken from the literature and used to construct a potential-pO diagram corresponding to the solvent eutectic Na,KN03 at 229 °C. The presence or absence of H20 was taken into account. The representation resolves previous apparent contradictions in the literature and explains the individual behaviour of these solvents.142 

Nitric acid is one of the three major acids of the modem chemical industiy and has been known as a corrosive solvent for metals since alchemical times in the thirteenth centuiy. It is now invariably made by the catalytic oxidation of ammonia under conditions which promote the formation of NO rather than the thermodynamically more favoured products N2 or N2O (p. 423). The NO is then further oxidized to NO2 and the gases absorbed in water to yield a concentrated aqueous solution of the acid. The vast scale of production requires the optimization of all the reaction conditions and present-day operations are based on the intricate interaction of fundamental thermodynamics, modem catalyst technology, advanced reactor design, and chemical engineering aspects of process control (see Panel). Production in the USA alone now exceeds 7 million tonnes annually, of which the greater part is used to produce nitrates for fertilizers, explosives and other purposes (see Panel). 

Anhydrous HNO3 can be obtained by low-pressure distillation of concentrated aqueous nitric acid in the presence of P4O10 or anhydrous H2SO4 in an all-glass, grease-free apparatus in the dark. The molecule is planar in the gas phase 

Mellor, a Comprehensive Treatise on Inorganic and Theoretical Chemistry, Vol. 8, pp. 555-8, Longmans, Green, London, 1928. 

144 T K. Derry and T. I. Williams, A Short History of Technology from the Earliest Times to AD 1900, Oxford University Press, Oxford, 1960, 782 pp. 

In addition, the liquid undergoes self-ionic dissociation to a greater extent than any other nominally covalent pure liquid (cf. BF3.2H2O, p. 198) initial autoprotolysis is followed by rapid loss of water which can then react with a further molecule of HNO3  

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Cyanides Acids, water or steam, fluorine, magnesium, nitric acid and nitrates, nitrites... 

Control of NO emissions from nitric acid and nitration operations is usually achieved by NO2 reduction to N2 and water using natural gas in a catalytic decomposer (123—126) (see Exhaust control, industrial). NO from nitric acid/nitration operations is also controlled by absorption in water to regenerate nitric acid. Modeling of such absorbers and the complexities of the NO —HNO —H2O system have been discussed (127). Other novel control methods have also been investigated (128—129). Vehicular emission control is treated elsewhere (see Exhaust control, automotive). 

Ferrous Sulfdte Titration. For deterrnination of nitric acid in mixed acid or for nitrates that are free from interferences, ferrous sulfate titration, the nitrometer method, and Devarda s method give excellent results. The deterrnination of nitric acid and nitrates in mixed acid is based on the oxidation of ferrous sulfate [7720-78-7] by nitric acid and may be subject to interference by other materials that reduce nitric acid or oxidize ferrous sulfate. Small amounts of sodium chloride, potassium bromide, or potassium iodide may be tolerated without serious interference, as can nitrous acid up to 50% of the total amount of nitric acid present. Strong oxidizing agents, eg, chlorates, iodates, and bromates, interfere by oxidizing the standardized ferrous sulfate. 

All of these species are very soluble in a rain or cloud drop and are an important source of atmospheric aerosols. For ammonia and ammonium, the condensed phases (I and s) represent approximately two-thirds of the total atmospheric burden, whereas for nitric acid and nitrates, about two-thirds is in the gas phase (Soderlund and Svensson, 1976). 

Reactions of nitric acid and nitrates with alcohols... 

Nitric acid and nitrates are important chemicals. For example, black powder (also known as gunpowder) has been used for centuries, and it is a mixture containing 75% KN03, 15% C, and 10% S. The mixture is made into flakes while wet and then dried. Except for large guns on naval vessels, it has been replaced by nitrocellulose (smokeless) powder that also contains small amounts of certain additives. 

Copper(II) sulfate Cumene hydroperoxide Cyanides Cyclohexanol Cyclohexanone Decaborane-14 Diazomethane 1,1-Dichloroethylene Dimethylformamide Hydroxylamine, magnesium Acids (inorganic or organic) Acids, water or steam, fluorine, magnesium, nitric acid and nitrates, nitrites Oxidants Hydrogen peroxide, nitric acid Dimethyl sulfoxide, ethers, halocarbons Alkali metals, calcium sulfate Air, chlorotrifluoroethylene, ozone, perchloryl fluoride Halocarbons, inorganic and organic nitrates, bromine, chromium(VI) oxide, aluminum trimethyl, phosphorus trioxide... 

Nitrogen (N, [He]2s22/ 3), symbol and name after the Greek words vi/rpov stvo— par (nitre forming) because it is a constituent of nitric acid and nitrates. Discovered (1772) by Daniel Rutherford. 

Nitrogen NMR data have been obtained using both the low-abundance, spin = 1/2 N and the predominant spin = 1 N nuclei. Several different references have been used for nitrogen NMR including aqueous ammonia, ammonium salts, acetonitrile, nitric acid, and nitrates. Current opinion favors neat nitromethane, and the compilation of the known data for 1,4-oxazines (Table 6) is expressed with respect to this reference and arranged in order of the observed chemical shift. For the C-labeled compound 87, carbamate rotamers lead to two separate signals and the value of 7c n can be determined -283.98 (d, J 9) and -284.46 (d, 7 11) <2001JOC8010>. 

C3Hs.N(N02).CeH(N02)4 mw 346.17, N 24.28% ctysts, mp 96° sol in benz toluene may be prepd by Creating 3,4-dinitro-N,N-diethylaniline and sodium nitrate in dilute nitric acid and nitrating the resulting product with nitric acid (d 1.49) and sulfuric acid Refs 1) Beil 12, (372) 2) P. van Romburgh... 

Nitric Acid and Nitrates. The use of nitric acid as a major component in liquid oxidizers dates back to at least World War II when it was used in a mixture with oleum (88 wt. % white fuming nitric acid and 12 wt. % oleum) and was denoted as mixed acid. In later years its use as white fuming nitric acid (WFNA) and inhibited white fuming nitric acid (IWFNA) developed because of its higher performance capabilities in these forms. These acids are fairly pure nitric acid WFNA contains a maximum of 2 wt. % H20 and 0.5 wt. % N02 IWFNA addi-... 

Chrpmium trioxide ( chromic anhydride ), chromates and dichromates. Concentrated nitric acid and nitrates. 

Diphenylamine is sparingly soluble in water, but is readily soluble in alcohol and acids. It may be used as reagent for nitric acid and nitrates. Its use as a Stabilizer is particularly important. 

Nitric acid and nitrates are still frequently formulated incorrectly as ... 

The extraordinary demand for nitric acid and nitrates brought about by the abnormal conditions consequent on the great European War of 1914 and succeeding years gave a powerful impetus to the development of synthetic methods for the fixation of atmospheric nitrogen. For an account of these developments reference should be made to Volume VI. of this series. 

Non-Reversible Processes. —Reactions of the non-reversible type, i.e., with systems which do not give reversible equilibrium potentials, occur most frequently with un-ionized organic compounds the cathodic reduction of nitrobenzene to aniline and the anodic oxidation of alcohol to acetic acid are instances of this type of process. A number of inorganic reactions, such as the electrolytic reduction of nitric acid and nitrates to hydroxylamine and ammonia, and the anodic oxidation of chromic ions to chromate, are also probably irreversible in character. Although the problems of electrolytic oxidation and reduction have been the subject of much experimental investigation, the exact mechanisms of the reactions involved are still in dispute. For example, the electrolytic reduction of the compound RO to R may be represented by... 

Nitric Acid and Nitrate Activation. The reactions of HNO3, nitrates, and nitrogen oxides with lignocellulosic materials have been a subject of numerous publications. The specific transformations can be subdivided into acid reactions, oxidation reactions, and nitration-esterification reactions. With HNO3 and more acidic salts the acid reactions predominate at higher dilutions, and parallel those of aqueous solutions of H2SO4 and other similar acids. Oxidation of cellulose results primarily in oxidation of primary hydroxyls to carboxyls, with the secondary hydroxyls oxidized less. Nitration leads... 

The modern name of nitrogen was first suggested in 1790 by French chemist Jean Antoine Claude Chaptal (1756-1832). This name made sense to chemists when they realized that the new gas was present in both nitric acid and nitrates. Thus, nitrogen means nitrate and nitric acid (nitro-) and origin of (-gen). 

Nitrogen oxides other than nitrogen dioxide have been studied for possible adverse health effects. Chemical analysis of ambient aerosols collected in southern California has revealed that nitrates exhibit particularly high values compared to other parts of the United States. These aerosols are generally acidic in nature and are composed of nitric acid and nitrate salts that are formed through photochemical reactions with nitrogen dioxide and other oxides of... 

The usual effect of increasing the acid concentration is reported to be an increase in the (due to increased amounts of the extractable MA3 in the aqueous phase) followed by a decrease in the (due to formation of the extractant-HNC adduct), resulting in a maximum extraction at an acid concentration between 2 and 6 M. However, one study has noted an increase in americium extraction at nitric acid concentrations from 12 to 16 M. These data are not consistent with the usual view of americium distribution dependence on nitric acid and nitrate concentration, and the authors hypothesize that a TBP HN03 adduct, which is a stronger extractant for americium than TBP alone, is formed above 8 M HNO3 and an organic-phase complex of Am(N03)3 (TBP mHNC ) is formed rather than Am(N03)3 nTBP (26). While one may not absolutely discount this possibility, additional factors such as the extraction of HAm(N03) and deviations from ideal activities in such concentrated acid solutions should definitely be considered. 

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