Aqueous nitrogen solutions

Uses. Since 1947, 70 to 85% of the annual USA production of nitric acid has gone into the production of NH4 nitrate fertilizer, initially in the form of solid prills currently, increasing amounts have been supplied mixed with excess ammonia and/or urea as aqueous nitrogen solution for direct application to the soil. Some 15% is used in explsj (nitrates nitro compds), and about 10% is consumed by the chemical industry. As the red fuming acid or as nitrogen tetroxide, nitric acid is used extensively as the oxidizer in proplnts for rocketry. It is estimated that current USA capacity for nitric acid is in excess of 10 million tons (Refs 30, 34, 36 37)... 

Aqueous nitrogen solutions (26-32% N). These are usitally solutions of mixtures of ammonium nitrate and urea, and are commonly used on farm crops (liquid fertilisers). 

Nitrogen and sulphur absent, (i) If only one halogen is present, acidify with dilute nitric acid and add excess of silver nitrate solution. A precipitate indicates the presence of a halogen. Decant the mother liquor and treat the precipitate with dilute aqueous ammonia solution If the precipitate is white and readily soluble in the ammonia solution, chlorine is present if it is pale yellow and difficultly soluble, bromine is present if it is yellow and insoluble, then iodine is indicated. Iodine and bromine should be confirmed by the tests given below. 

Carbon dioxide gas diluted with nitrogen is passed continuously across the surface of an agitated aqueous lime solution. Clouds of crystals first appear just beneath the gas-liquid interface, although soon disperse into the bulk liquid phase. This indicates that crystallization occurs predominantly at the gas-liquid interface due to the localized high supersaturation produced by the mass transfer limited chemical reaction. The transient mean size of crystals obtained as a function of agitation rate is shown in Figure 8.16. 

The commercial production of NaN02 is achieved by absorbing oxides of nitrogen in aqueous Na2C03 solution ... 

An arenediazonium ion 1 in aqueous alkaline solution is in equilibrium with the corresponding diazohydroxide 4 The latter can upon deprotonation react with diazonium ion 1, to give the so-called anhydride 5. An intermediate product 5 can decompose to a phenyl radical 6 and the phenyldiazoxy radical 7, and molecular nitrogen. Evidence for an intermediate diazoanhydride 5 came from crossover experiments " ... 

For the Flofmann rearrangement reaction, a carboxylic amide 1 is treated with hypobromite in aqueous alkaline solution. Initially an iV-bromoamide 4 is formed. With two electron-withdrawing substituents at nitrogen the A -bromoamide shows NFI-acidity, and can be deprotonated by hydroxide to give the anionic species 5. 

The reactor is loaded with a solution of emulsifier in an organic solvent and the aqueous monomer solution (20-60%) is dispersed in the organic phase by stirring. The obtained emulsion is deoxygenated by purging dry nitrogen or by multiple evacuation and thermostated at 30-60°C. Then, an initiator solution is introduced in the reaction mixture and the process is carried out at 30-60°C for 3-6 h, after which the reaction mixture is aged for 1-5 h. 

Samples for studies of CDx effects on fluorescence enhancement in organic solution were prepared using pyrene, because pyrene possesses a long lifetime and is very susceptible to quenching and enhancement in solution (23). An aliquot of pyrene stock solution in cyclohexane was placed under a nitrogen purge to evaporate the cyclohexane. Samples were redissolved in a 1 A mixture of Isopropyl ether and 1-butanol, which was saturated with aqueous CDx solution. Pyrene samples were also prepared in which the organic solvent was not saturated with CDx solution. The mixed solvent was used in order to minimize the effects of ether evaporation and thus allow more accurate quantitation. Fluorescence measurements were made on diluted samples of these solutions. The solvent used to make up the... 

P 23] Aqueous NaOH solutions of 0.1, 1.0 and 2.0 M were used, fed by pumps to the micro devices [5]. Carbon dioxide was supplied as a mixture with nitrogen, the flow rate being set by a mass-flow controller, liqmd samples were taken and subjected to carbonate analysis (see original citation in [5]). 

Iron(II) complexes are often included in studies when complexes are prepared from a large number of different metal ions. 2-formylpyridine thiosemicarbazone, 5, forms brown [Fe(5)2A2] (A = Cl, Br) when prepared in ethanol and [Fe(5-H)2] from aqueous alcohol solution [156], All of these complexes are diamagnetic. The resonance Raman and infrared spectra of [Fe(5-H)2] were examined in detail [130] and coordination occurs via the pyridyl nitrogen, azomethine nitrogen and thiol sulfur. There is appreciable d-d sulfur-to-iron(II) Jt-bonding. Solution studies of iron(II) complexes of some 5-substituted-2-formylpyridine thiosemicarbazones have been reported [157], but no solids... 

Fitzgerald42 found that the antibody response of rabbits toward 1.5% aqueous dextran solutions (both types) varied with the nitrogen (t. e., bacterial) content of the dextran. Injections were administered both interperitoneally and intravenously, and no antibody production resulted when the nitrogen content of the dextrans was below 0.2%. 

The mercury analyses were conducted using a Coleman Instruments mercury analyser (MAS-50) equipped with a recorder. The aqueous sample solution was contained in a 250 ml Pyrex glass bubbler placed at one end of a sampling train employing nitrogen as the purging and carrier gas. A schematic diagram of the entire system is shown in Fig. 5.12. 

The diamines and their mono- and di-protonated ions can exist in various conformations, in which the nitrogen lone pairs and the protons on nitrogen are directed in (i or i+) or directed out (o or o+) from the molecular cavity. Diprotonated l,10-diazabicyclo[8.8.8]hexacosane, for example, may exist in either of the three forms in equation (79). When the out-out isomer of l,10-diazabicyclo[8.8.8]hexacosane bis hydrochloride (o+ o+) is dissolved in aqueous acidic solution, isomerisation to the in-in isomer (i+ i+) occurs so... 

It was of importance to determine the impact on performance of (E5)-den-drimer-Ab complexes should they be exposed to unintentional oxidizing conditions. To study such a challenge, the aqueous buffered solutions of naked (E5)-dendrimer at pH 2.5,7.0 and 9.0 were exposed separately to a bubble stream of nitrogen, oxygen or air for 15 days at room temperature. These solutions were... 

Reactions which cannot be perturbed by changing an external parameter may be detected by the stopped-flow method. The detection system of this apparatus is the same as that of the pressure-jump apparatus described previously (10). For this system, aqueous electrolyte solution and an aqueous metal-oxide suspension are mixed rapidly by operating an electric solenoid valve under nitrogen gas of 7 atm. The dead time of this apparatus is 15 ms. 

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