Nitric acid purity

Saccharic acid. Use the filtrate A) from the above oxidation of lactose or, alternatively, employ the product obtained by evaporating 10 g. of glucose with 100 ml. of nitric acid, sp. gr. 1 15, until a syrupy residue remains and then dissolving in 30 ml. of water. Exactly neutralise at the boiling point with a concentrated solution of potassium carbonate, acidify with acetic acid, and concentrate again to a thick syrup. Upon the addition of 50 per cent, acetic acid, acid potassium saccharate sepa rates out. Filter at the pump and recrystaUise from a small quantity of hot water to remove the attendant oxahc acid. It is necessary to isolate the saccharic acid as the acid potassium salt since the acid is very soluble in water. The purity may be confirmed by conversion into the silver salt (Section 111,103) and determination of the silver content by ignition. 

Nickel sulfate also is made by the reaction of black nickel oxide and hot dilute sulfuric acid, or of dilute sulfuric acid and nickel carbonate. The reaction of nickel oxide and sulfuric acid has been studied and a reaction induction temperature of 49°C deterrnined (39). High purity nickel sulfate is made from the reaction of nickel carbonyl, sulfur dioxide, and oxygen in the gas phase at 100°C (40). Another method for the continuous manufacture of nickel sulfate is the gas-phase reaction of nickel carbonyl and nitric acid, recovering the soHd product in sulfuric acid, and continuously removing the soHd nickel sulfate from the acid mixture (41). In this last method, nickel carbonyl and sulfuric acid are fed into a closed-loop reactor. Nickel sulfate and carbon monoxide are produced the CO is thus recycled to form nickel carbonyl. 

The fire assay, the antecedents of which date to ancient Egypt, remains the most rehable method for the accurate quantitative determination of precious metals ia any mixture for concentrations from 5 ppm to 100%. A sample is folded iato silver-free lead foil cones, which are placed ia bone-ash cupels (cups) and heated to between 1000 and 1200°C to oxidize the noimoble metals. The oxides are then absorbed iato a bone-ash cupel (ca 99%) and a shiny, uniformly metaUic-colored bead remains. The bead is bmshed clean, roUed fiat, and treated with CP grade nitric acid to dissolve the silver. The presence of trace metals ia that solution is then determined by iastmmental techniques and the purity of the silver determined by difference. 

The manufacture of silver nitrate for the preparation of photographic emulsions requires silver of very high purity. At the Eastman Kodak Company, the principal U.S. producer of silver nitrate, 99.95% pure silver bars are dissolved in 67% nitric acid in three tanks coimected in parallel. Excess nitric acid is removed from the resulting solution, which contains 60—65% silver nitrate, and the solution is filtered. This solution is evaporated until its silver nitrate concentration is 84%. It is then cooled to prepare the first crop of crystals. The mother Hquor is purified by the addition of silver oxide and returned to the initial stages of the process. The cmde silver nitrate is centrifuged and recrystallized from hot, demineralized water. Equipment used in this process is made of ANSI 310 stainless steel (16). 

The refined arsenic trioxide is analysed for purity and also tested for solubihty, a term referring to its rate of reactivity with nitric acid this test is important if the arsenic is used in the manufacture of insecticides and herbicides. The product is graded for marketing as white soluble having 99% min AS2O2, white insoluble, or cmde having 95% min AS2O2. 

Arsenic trioxide may be made by burning arsenic in air or by the hydrolysis of an arsenic trihaUde. Commercially, it is obtained by roasting arsenopyrite [1303-18-0] FeAsS. It dissolves in water to a slight extent (1.7 g/100 g water at 25°C) to form a weaMy acidic solution which probably contains the species H AsO, orthoarsenous acid [36465-76-6]. The oxide is amphoteric and hence soluble in acids and bases. It is frequendy used as a primary analytical standard in oxidimetry because it is readily attainable in a high state of purity and is quantitatively oxidized by many reagents commonly used in volumetric analysis, eg, dichromate, nitric acid, hypochlorite, and inon(III). 

Suberic Acid. This acid is not produced commercially at this time. However, small quantities of high purity (98%) can be obtained from chemical supply houses. If a demand developed for suberic acid, the most economical method for its preparation would probably be based on one analogous to that developed for adipic and dodecanedioic acids air oxidation of cyclooctane to a mixture of cyclooctanone and cyclooctanol. This mixture is then further oxidized with nitric acid to give suberic acid (37). 

Fig. 4.4 Action of nitric acid of various concentrations on commercial-purity aluminium...

Nitric acid plants Tantalum heat exchangers and sparge pipes find extensive use in plants producing high purity nitric acid, ammonium nitrate and terephthalic acid. 

The concentration and purity of the fuming nitric acid is of considerable importance. It should have a sp. gr. of not less than 1.49 and should leave no residue on distillation. 

Note on the gravimetric standardisation of hydrochloric acid. The gravimetric standardisation of hydrochloric acid by precipitation as silver chloride is a convenient and accurate method, which has the additional advantage of being independent of the purity of any primary standard (compare Section 10.38). Measure out from a burette 30-40mL of the, say, 0.1M hydrochloric acid which is to be standardised. Dilute to 150 mL, precipitate (but omit the addition of nitric acid), and weigh the silver chloride. From the weight of the precipitate, calculate the chloride concentration of the solution, and thence the concentration of the hydrochloric acid. 

Oxidation of 4-methylcyclohexanone by addition of nitric acid at about 75°C caused a detonation to occur. These conditions had been used previously to oxidise the corresponding alcohol, but although the ketone is apparently an intermediate in oxidation of the alcohol, the former requires a much higher temperature to start and maintain the reaction. An OTS report, PB73591, mentions a similar violent reaction with cyclohexanone [1], Presence of nitrous acid is essential for the smooth oxidation of cycloalkanones with nitric acid to a, rw-hcxanedioic acids. Because high-purity nitric acid (free of nitrous acid) is now commonly available, addition of a little sodium or potassium nitrite to the acid is necessary before its use to oxidise cycloalkanones [2],... 

Add 2 ml of super purity acid (SPA) (or equivalent) nitric acid... 

Iodine is also given off to a small extent in dissolving the uranium metal in nitric acid, but larger amounts may be obtained on steam distillation after dissolution (5). Ruthenium is often removed from the fission products by distillation of the volatile tetroxide formed by oxidation with potassium permangate, sodium bismuthate, periodic acid (38) etc. The distillation goes readily and gives a product of good purity. 

Tucker et al. have separated " Tc from the fission product Mo using chromatographic aluminum oxide washed by dilute nitric acid at pH 1.5. Mo dissolved in the same dilute HNO3 of pH 1.5 is passed through the column which is then eluted with 0.1 M HNO3. Tc is only slightly adsorbed and can easily be eluted while molybdenum is retained on the column. The purity of technetium is 99.99%. 

Gaseous sample introduction into an ICP-MS presents different problems. Owing to its extremely sensitive nature, Dean et al. [13] introduced the sample as the gaseous hydride by a flow-injection approach. This was reasonably effective because lower volumes of samples and reagents were in use. They utibzed nitric acid as a carrier stream to prevent the formation of argon chloride species in the plasma. Argon chloride has the same mass as arsenic which is mono-isotopic, and this severely bmits arsenic determination. An additional problem was that the sensitivity was extremely dependent on the purity of reagents. 

The metal is not attacked by hydrochloric acid, nor does it react with dilute nitric and sulfuric acids. High purity selenium reacts slowly with concentrated nitric acid. The crude metal, however, dissolves in cold concentrated nitric acid. 

Exists in two adotropic modifications. Crystalline sihcon is made up of grayish-black lustrous needle-hke crystals or octahedral platelets cubic structure Amorphous sdicon is a brown powder. Other physical properties are density 2.33g/cm3 at 25°C melts at 1,414°C high purity liquid silicon has density 2.533 g/cm at its melting point vaporizes at 3,265°C vapor pressure 0.76 torr at 2,067°C Mohs hardness 6.5. Brinell hardness 250 poor conductor of electricity dielectiric constant 13 critical temperature 4°C calculated critical pressure 530 atm magnetic susceptibility (containing 0.085%Fe) 0.13x10 insoluble in water dissolves in hydrofluoric acid or a mixture of hydrofluoric and nitric acids soluble in molten alkalies. 

Since 5-Amino-tetrazole (ATZ) was not available commercially at that time, Benson (Ref 3) also reported a method for the synthesis of ATZ of 99% purity in 70-85% yield by reaction of Na nitrate aminoguanidine bicarbonate dissolved in nitric acid, followed by treatment with Na acetate. Davis (Ref 4) prepd Cal. 50 gun proplnts and determined the optimum percentage of 5 to 10% ATZ without DNEB (Dinitroethylbenzene), but coated with 5 to 0.8% DNT, gave acceptable service ballistics. 

Arsenic acid obtained by oxidizing arsenious oxide with nitric acid is satisfactory a syrupy acid of 80-85 Per cent purity can be obtained on the market. 

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