Nitric acid and nitrate solutions

As mentioned before, radiolysis of nitric acid has been an important and complicated subject in nuclear technology and much data has been accumulated not only in low LET radiblysis but also in a-radiolysis. The radiolysis study of the nitric acid started at the Oak Ridge National Laboratory in 1950s and many peculiar phenomena strongly dependent on the concentration were 

In recent times interests in atmospheric chemistry have got scientists together not only from radiation chemistry but also from other fields to investigate the characteristics of the NOg radical [10]. In addition, the treatment of the 

The yield of the NOj can easily be evaluated if a reliable molar absorption coefficient at known. While there have been several reported 

There are several reports on O2 gas evolution. A recent report analyzed the 

Furthermore, precise measurements of Ce formation in nitric acid and nitrate solutions in the presence and absence of Tl and the G-values of the 

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G-values of H2, HNO3, O2, H2O2 have been determined by different researchers but the agreement is not satisfactory. Most of the references related to the radiolysis of nitric acid and nitrate solutions was recently summarized elsewhere [17]. 

The reduction of oxidizing acids and their anions may also be considered, particularly in the case of nitric acid and nitrate solutions ... 

Mercurous Nitrate. Mercurous nitrate [10415-75-5] Hg2N20 or Hg2(N02)2, is a white monoclinic crystalline compound that is not very soluble in water but hydrolyzes to form a basic, yellow hydrate. This material is, however, soluble in cold, dilute nitric acid, and a solution is used as starting material for other water-insoluble mercurous salts. Mercurous nitrate is difficult to obtain in the pure state directly because some mercuric nitrate formation is almost unavoidable. When mercury is dissolved in hot dilute nitric acid, technical mercurous nitrate crystallizes on cooling. The use of excess mercury is helpful in reducing mercuric content, but an additional separation step is necessary. More concentrated nitric acid solutions should be avoided because these oxidize the mercurous to mercuric salt. Reagent-grade material is obtained by recrystaUization from dilute nitric acid in the presence of excess mercury. 

A three-necked round-bottom flask is fitted with a dropping funnel, a thermometer, and a magnetic stirrer and is heated in a water bath to 30°. Tetralin (1.32 g, 0.01 mole) and 50 ml of 3.5 Anitric acid solution are placed in the flask and brought to temperature. Ceric ammonium nitrate (21.9 g, 0.04 mole) is dissolved in 100 ml of 3.5 N nitric acid, and the solution is added dropwise to the reaction mixture at a rate such that the temperature does not rise and only a pale yellow color is evident in the reaction mixture. At the completion of the reaction (1 to 2 hours), the mixture should be colorless. The solution is cooled to room temperature, diluted with an equal volume of water, and extracted twice with ether. The ether solution is dried with anhydrous sodium sulfate, filtered, and the ether is evaporated. The residue may be distilled to yield a-tetralone (bp 113-11676 mm or 170749 mm) or may be converted directly to the oxime, which is recrystallized from methanol, mp 88-89°. 

The 0 -(p-nltrophenyl)-a-ethyl-glutarimide starting material can be prepared as follows 217 g of 0 -phenyl-a-ethyl-glutarimlde are dissolved in 800 g of concentrated sulfuric acid with subsequent cooling to about -10°C and nitration Is carried out at -10°to -f10°C by slow addition of a mixed acid consisting of 110 g of concentrated suifuric acid and 110 g of 63% nitric acid. The nitration solution is stirred into ice, the separated nitro compound taken up in methylene or ethylene chloride, the solution washed with water and sodium carbonate solution until... 

Chlorides and Sulphates. — Decompose 10 gm. of sodium oxalate by heating in a platinum crucible, best over an alcohol lamp (illuminating gas contains sulphur). The carbonate formed is dissolved in nitric acid, and the solution filtered off from the carbon. On adding silver nitrate solution to half of the filtrate, no reaction for hydrochloric acid should be obtained and in the other half no reaction for sulphuric acid should be obtained on adding barium nitrate solution. 

Fig. 8. Ultra-violet absorption spectra of nitric acid-ammonium nitrate solutions (R. N. Jones and Thorn [58a]).

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... 

To a 6-101. flask equipped with a stirrer and three dropping funnels add 785 g acetic acid, 13 g acetic anhydride and 17 g of paraformaldehyde keeping the tempetaUue at 44 1 C. Add over 15 min a solution of 101 g of hexamine in 165 g acetic acid, 320 g of acetic anhydride and 180 g of ammonium nitrate nitric acid solution prepared by dissolving 840 g of ammonium nitrate in 900 g of nitric acid (99% concentration). The hexamine ami nitric acid arc added continuously in correct proportions. The mixture is stirred for 15 min. After that are added 320 g of acetic anhydride and 271 g of nitric acid-ammonium nitrate solution in that proportion and then 160 g of acetic anhydride are added in bulk. Tire mixture is stirred for 60 min., 350 g of hot water are added and refluxed for 30 min. The content is cooled to 20 C by adding ice, the precipitate is collected and washed with three portions of cold water. 

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. 

Analogous to perchloric acid. Formed when iodate of soda is heated with bleaching liquor chloride of soda), or when chlorine is passed through a hot solution of 7 parts of diy carbonate of soda in 100 of water, in which 1 part of iodine is suspended, as long as a white crystalline salt is deposited. This is periodate of soda. It is dissolved in dilute nitric acid, and nitrate of lead added, which forms a precipitate of periodate of lead. This last salt is boiled with diluted sulphuric "acid, avoiding excess, and the filtered solution, or evaporation, yields crystals of periodic acid, in transparent plates. 

In the production of ammonium nitrate through the neutralization process as shown in the diagram, ammonia gas is passed into nitric acid and the solution evaporated until practically all of the water has been eliminated. The reaction involved is essentially as expressed by the equation... 

Paper chromatography has been used by a number of workers for separation of RaD(Pb °), RaE(Bl ) and RaP(Po °) mixtures. Levi and Danon (Ll4) used a butanol-propanol mixture which had been shaken with a nitric acid, lithium nitrate solution (item 63, Table XX). Using Whatman No. 1 paper they obtained separation in 16 hours at room temperature. No difference in R. values were obtained with or without weighable quantities of lead and bismuth carriers,... 

Ceric Solution. 0.25 g cerium ammonium nitrate is mixed with 10 ml dilute nitric acid and the solution diluted to 100 ml with water. 

A weighed sample is combusted in an oxygen filled flask over dilute nitric acid. Silver nitrate solution is then added and the resulting silver chloride, i.e., chlorine, estimated turbidimetrically at 420 nm using a grating spectrophotometer. 

Dithionites reduce diammine silver nitrate to silver, which is dissolved in nitric acid and the solution titrated against standardised thiocyanate solution. 

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