Nitric acid solution , precipitates

Certain features of the addition of acetyl nitrate to olefins in acetic anhydride may be relevant to the mechanism of aromatic nitration by this reagent. The rapid reaction results in predominantly cw-addition to yield a mixture of the y -nitro-acetate and y5-nitro-nitrate. The reaction was facilitated by the addition of sulphuric acid, in which case the 3rield of / -nitro-nitrate was reduced, whereas the addition of sodium nitrate favoured the formation of this compound over that of the acetate. As already mentioned ( 5.3. i), a solution of nitric acid (c. i 6 mol 1 ) in acetic anhydride prepared at — 10 °C would yield 95-97 % of the nitric acid by precipitation with urea, whereas from a similar solution prepared at 20-25 °C and cooled rapidly to —10 °C only 30% of the acid could be recovered. The difference between these values was attributed to the formation of acetyl nitrate. A solution prepared at room... 

Sonnenschein s reagent (alkaloid detection) a nitric acid solution of ammonium molybdate is treated with phosphoric acid. The precipitate so produced is washed and boiled with aqua regia... 

Oxalates. Stable oxalates of Pu(III), Pu(IV), and Pu(VI) are known. However, only the Pu(III) and Pu(IV) oxalates are technologically important (30,147). Brilliant green plutonium(III) oxalate [56609-10-0] precipitates from nitric acid solutions containing Pu(III) ions upon addition of oxaUc acid or sodium oxalate. The composition of the precipitate isPu2(C20 2 10H2O. A homogeneous oxalate precipitation by hydrolysis of diethyl oxalate at... 

Qua.driva.Ient, Zirconium tetrafluoride is prepared by fluorination of zirconium metal, but this is hampered by the low volatility of the tetrafluoride which coats the surface of the metal. An effective method is the halogen exchange between flowing hydrogen fluoride gas and zirconium tetrachloride at 300°C. Large volumes are produced by the addition of concentrated hydrofluoric acid to a concentrated nitric acid solution of zirconium zirconium tetrafluoride monohydrate [14956-11-3] precipitates (69). The recovered crystals ate dried and treated with hydrogen fluoride gas at 450°C in a fluid-bed reactor. The thermal dissociation of fluorozirconates also yields zirconium tetrafluoride. 

To a stirred and refluxing solution of 40 parts of benzene and 35 parts of dimethylformamide (both solvents previously dried azeotropically) are added successively 1.6 parts of sodium hydride and 7.7 parts of Ct-(2,4-dichlorophenyl)imidazole-1-ethanol, (coolingon ice is necessary). After the addition is complete, stirring and refluxing is continued for 30 minutes. Then there are added 7.8 parts of 2,6-dichlorobenzyl chloride and the whole is stirred at reflux for another 3 hours. The reaction mixture is poured onto water and the product 1-[2,4-dichloro-/3 (2,6-dichlorobenzyloxy)phenethyl] imidazole, is extracted with benzene. The extract is washed twice with water, dried, filtered and evaporated in vacuo. The bese residue is dissolved in a mixture of acetone and diisopropyl ether and to this solution is added an excess of concentrated nitric acid solution. The precipitated nitrate salt is filtered off and recrystallized from a mixture of methanol and diisopropyl ether, yielding 1-[2,4-dichloro- (2,6-dichlorobenzyl-oxv)phenethyl] imidazole nitrate melting point 179°C. 

Procedure. The solution should not exceed 50 mL in volume, all metallic elements should be present as nitrates, and the cerium content should not exceed 0.10g. Treat the solution with half its volume of concentrated nitric acid, and add 0.5 g potassium bromate (to oxidise the cerium). When the latter has dissolved, add ten to fifteen times the theoretical quantity of potassium iodate in nitric acid solution (see Note) slowly and with constant stirring, and allow the precipitated cerium(IV) iodate to settle. When cold, filter the precipitate through a fine filter paper (e.g. Whatman No. 42 or 542), allow to drain, rinse once, and then wash back into the beaker in which precipitation took place by means of a solution containing 0.8 g potassium iodate and 5 mL concentrated nitric acid in 100 mL. Mix thoroughly, collect the precipitate on the same paper, drain, wash back into the beaker with hot water, boil, and treat at once with concentrated nitric acid dropwise until the precipitate just dissolves (20-25 mL... 

Alternatively, treat the chlorate solution with excess of sulphur dioxide, boil the solution to remove the excess of the gas, render slightly acid with nitric acid, and precipitate the silver chloride as above. 

Determination of phosphate as ammonium molybdophosphate. This may be readily effected by precipitation with excess of ammonium molybdate in warm nitric acid solution arsenic, vanadium, titanium, zirconium, silica and excessive amounts of ammonium salts interfere. The yellow precipitate obtained may be weighed as either ammonium molybdophosphate, (NH4)3[PMo12O40], after drying at 200-400 °C, or as P205,24Mo03, after heating at 800-825 °C for about 30 minutes. 

Sample preparation is rather involved. A sample of urine or fecal matter is obtained and treated with calcium phosphate to precipitate the plutonium from solution. This mixture is then centrifuged, and the solids that separate are dissolved in 8 M nitric acid and heated to convert the plutonium to the +4 oxidation state. This nitric acid solution is passed through an anion exchange column, and the plutonium is eluted from the column with a hydrochloric-hydroiodic acid solution. The solution is evaporated to dryness, and the sample is redissolved in a sodium sulfate solution and electroplated onto a stainless steel planchette. The alpha particles emitted from this electroplated material are measured by the alpha spectroscopy system, and the quantity of radioactive plutonium ingested is calculated. Approximately 2000 samples per year are prepared for alpha spectroscopy analysis. The work is performed in a clean room environment like that described in Workplace Scene 1.2. 

Polonium may be purified by various processes. Such purification methods include precipitation of polonium as sulfide and then decomposing the sulfide at elevated temperatures spontaneous decomposition of polonium onto a nickel or copper surface and electrolysis of nitric acid solutions of polonium-bismuth mixture. In electrolytic purification polonium is electrodeposited onto a platinum, gold, nickel, or carbon electrode. 

In one acid digestion process, monazite sand is heated with 93% sulfuric acid at 210°C. The solution is diluted with water and filtered. Filtrate containing thorium and rare earths is treated with ammonia and pH is adjusted to 1.0. Thorium is precipitated as sulfate and phosphate along with a small fraction of rare earths. The precipitate is washed and dissolved in nitric acid. The solution is treated with sodium oxalate. Thorium and rare earths are precipitated from this nitric acid solution as oxalates. The oxalates are filtered, washed, and calcined to form oxides. The oxides are redissolved in nitric acid and the acid solution is extracted with aqueous tributyl phosphate. Thorium and cerium (IV) separate into the organic phase from which cerium (IV) is reduced to metalhc cerium and removed by filtration. Thorium then is recovered from solution. 

Dichloro-diethylenediamino-cobaltic Nitrate, [Co en2Cl2] N03, is precipitated almost completely from a solution of the chloride by nitric acid. The precipitate is collected, washed with acid and then with alcohol. It is sparingly soluble in water, and if heated with water for some time gives a violet solution. 

See how silver nitrate reacts with a solution of sodium orthophosphate. Note the colour of the precipitate. Write the equation of the reaction. Does the substance dissolve in a 1 A nitric acid solution ... 

To prepare molybdenum liquid for determining the phosphate ion, dissolve 50 g of ammonium sulphate in 450 ml of a 68% nitric acid solution and 150 g of ammonium molybdate in 400 ml of distilled water. Cool the second solution to room temperature and pour it into the first one with constant stirring. Bring the total volume of the solution up to one litre. In a few days, filter off the solution for the precipitate. 

Pour 2-3 ml of a 10 % nitric acid solution into 2-3 ml of a 20 % ammonium molybdate solution. What substance precipitates What is its colour Wash the precipitate with water by decantation and divide it into two parts. React one part of the precipitate with an excess of concentrated hydrochloric acid and the other with a 20% sodium hydroxide solution. Explain the results. Write the equations of the reactions. Under what conditions does molybde-num(Vl) oxide dihydrate form ... 

Divide the preparation obtained into three parts. Boil one portion in a test tube with water (how does the colour of the precipitate change ), add a dilute acid solution to the second tube, and roast the third one in a crucible at 800 °C. What substances are obtained See how the substance formed after roasting reacts with a concentrated nitric acid solution. Write the equations of the reactions. 

Lead Sulphide. Prepare lead sulphide by precipitating it from an aqueous solution of lead acetate, pour the solution off the precipitate, and treat the latter with a dilute nitric acid solution. What is obtained Write the equations of the reactions and explain their course. 

Preparation of -Stannic Acid. Treat 0.5 g of tin with a 40-50 % nitric acid solution with heating. What do you observe Thoroughly wash the precipitate with water by decantation. See how P-stannic acid reacts with alkalies and acids. Compare the chemical activity of cs- and P-stannic acids. 

Preparation and Properties of Lead(IV) Oxide, a. Prepare a saturated transparent solution of chlorinated lime and a solution of 3 g of lead acetate in 5 ml of water. Add an equal volume of a lead acetate solution heated to 50 °C to the first solution while stirring it. Heat the reaction mixture to 100-110 °C. Wash the precipitate first with water by decantation, and next with a dilute nitric acid solution (what ions are washed off here ). Filter off the product, again wash it two or three times on the funnel with water and dry it at 100 °C. Keep the preparation. Write the equation of the reaction. 

The nitration is carried out with a large excess of anhydrous nitric acid (10 parts of acid to 1 part of sulphamide). The product is precipitated by pouring the nitric acid solution into water. 

The nitratocomplexes MIAm02(N03)3 (M1 = Rb or Cs424) are precipitated from nitric acid solutions of americium(VI). The IR spectrum of RbAm02(N03)3 has been reported.249 Hydrated phosphato, arsenato and sulfato complex salts are included under Aqua species in the preceding section. 

The only interference is from 82Br which is, of course, more serious if counting is done with a Nal detector. Bromide is removed by adding bromide carrier to the nitric acid solution of the products at 40°C and precipitating with silver nitrate. Mercuric bromide is soluble in warm dilute nitric acid and is quantitatively retained in solution. 

Cyanogen, Chlorine, and Bromine.—Shake 0.5 gm. of powdered iodine with 20 cc. of water, and filter. To 10 cc. of the filtrate, add, drop by drop, decinormal sodium thiosulphate solution until decolorized, then add a granule of ferrous sulphate, 1 drop of ferric chloride solution and 2 cc. of sodium hydroxide solution. Warm to about 60° C., and add 10 cc. of hydrochloric acid. The liquid should not acquire a blue color. Filter, and to 10 cc. of the filtrate add 1 cc. of ammonia water, 5 drops of silver nitrate solution, and again filter. On adding to the filtrate 2 cc. of nitric acid no precipitate, and not more than an opalescent turbidity, should develop. ... 

The foregoing nitric acid solution of polymerised c /cZoselenopropane after removal of the oxalic acid gives a viscous residue. After treatment with sodium acetate, addition of potassium iodide precipitates the brick-red diselenodi-iodide. The di-iodide occurs when hydriodic acid acts on trimethylenediselenious acid or when a chloroform solution of C2/cZotrimethylene diselenide is treated with iodine. It dissolves in warm chloroform or benzene, but is very sparingly soluble in acetone or alcohol it melts to a red liquid at 124° C. 

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