Ammonium Nitrate Titration

In this procedure [3, 12, 13] a known excess of standard ceric ammonium nitrate solution is added to an azide solution or slurry. The excess ceric ammonium nitrate is titrated with standard ferrous ammonium sulfate or sodium oxalate, using ferroin as indicator. The method is extremely simple and flee from hazard once the reagents have been mixed. A serious drawback is that dextrin and polyvinyl alcohol are oxidized by ceric ion. Blay [1] reports gelatin and carboxymethyl cellulose are not oxidized. The method is as follows. 

025 M solution of orZ//o-phenanthroline-ferrous ammonium sulfate indicator is prepared by dissolving 1.487 g of orzAo-phenanthroline monohydrate in 100 ml of an aqueous ferrous ammonium sulfate solution, containing 0.980 g of ferrous ammonium sulfate hexahydrate per 100 ml. 

Dilute perchloric acid solution prepared from 60 ml of 70-72% perchloric acid solution is diluted to 1 liter with distilled water. 

The ceric ammonium nitrate solution is standardized against reference sodium oxalate, available from the National Bureau of Standards, in the following manner Transfer a weighed portion of 0.25-0.30 g of the sodium oxalate to a 250-ml beaker, add 100 ml dilute perchloric acid solution, stirring the mixture until the salt is completely dissolved. The solution is cooled to room temperature, 2 drops of the or/Ao-phenanthroline-ferrous ammonium sulfate indicator is added, and the solution is titrated with the ceric ammonium nitrate solution until its color changes from faint red to faint blue. 

The normality of the ceric ammonium nitrate solution is given by  

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Either the Mohr titration or the adsorption indicator method may be used for the determination of chlorides in neutral solution by titration with standard 0.1M silver nitrate. If the solution is acid, neutralisation may be effected with chloride-free calcium carbonate, sodium tetraborate, or sodium hydrogencarbonate. Mineral acid may also be removed by neutralising most ofthe acid with ammonia solution and then adding an excess of ammonium acetate. Titration of the neutral solution, prepared with calcium carbonate, by the adsorption indicator method is rendered easier by the addition of 5 mL of 2 per cent dextrin solution this offsets the coagulating effect of the calcium ion. If the solution is basic, it may be neutralised with chloride-free nitric acid, using phenolphthalein as indicator. 

Ammonium thiocyanate-silver nitrate titrations (Volhard s Method). 

AMMONIUM THIOCYANATE-SILVER NITRATE TITRATIONS (VOLHARD S METHOD)... 

The formation of S-alkyl thiosulfate (Bunte salt) by the reaction of alkyl halide and sodium thiosulfate has been well known. Whereas a patent claimed the formation of Bunte salt from PECH and sodium thiosulfate (23), the reaction hardly proceeded in DMF owing to low solubility of sodium salt. On the other hand, both ammonium thiosulfate and PECH were soluble in HMPA-H20 (7 1 vol/vol) and the reaction proceeded homogeneously. Water soluble Bunte salt (j2, v(S0), 1200, 1020 cm-1) was isolated by pouring the reaction mixture into water and salting out with ammonium chloride. The DS based on the mercuric nitrate titration was in nearly accord with that on elemental analysis. The DS values depended on the thiosulfate concentration were shown below. 

Ceric ammonium nitrate is used as a volumetric oxidizing reagent in many oxidation-reduction titrations. Cerium(IV) ion is a strong oxidant simdar to permanganate ion. It is the most widely-used primary standard among all Ce(IV) compounds. Other apphcations of this compound are in organic oxidation reactions and as a catalyst in polymerization of olefins. 

Procedure for Ammonium Nitrate. Transfer a 25-ml aliquot from the bottle of step 6 to 100 ml of the neutralized form aldehyde-water soln in a 400-ml beaker, add 4 drops of 1% phenolphthalein (or thymolphthalein) indicator and titrate to a pink color with. 0.5N NaOH. Add 2ml of NaOH in excess, cover the beaker, and let stand for 5 mins. Back-titrate with 0.1N HCl to pH 8.5 (glass-calomel electrode system)... 

Oxidation states higher than + 3 are exhibited by Ce, Pr, and Tb, but only Ce4+ is stable (kinetically) in water. It is a very strong oxidizing agent in aqueous solution ( ° = 1.74 V) and is used as a volumetric standard in redox titrations. Some of its salts [e.g., cerium(IV) ammonium nitrate, cerium(IV) sulfate] find application in... 

In the titration of thioacetamide with silver nitrate in distilled water and in slightly acidic or basic solution, a black precipitate of silver sulfide formed. The other products of the reaction were ammonium nitrate and acetic acid. Two reaction pathways have been suggested for the course of this reaction, Scheme 3 and equation (24).349,330 In the presence of 0.1 MHN03, the reaction proceeded similarly. However, in 0.5 M or more concentrated HN03 solutions a different reaction took place. Under these conditions a light, pearly precipitate was formed and a silver thioacetamide complex was obtained. 

Visual titration was also reported, the excess of silver being titrated with potassium thiocyanate in the presence of ferric ammonium sulfate indicator [51]. Mercuric nitrate titrations were also reported [62]. 

Urtder Preparation of Fertilizer Grade Am-monium (titrate. This process has not been used for making ammonium nitrate fertilizer since 1948, as mentioned above... 

In practice this determination is carried out by adding to a weighed quantity of the chloropicrin in a small flask fitted with a condenser, an excess of an aqueous-alcoholic solution of sodium sulphite, prepared by dissolving 10 gm. sodium sulphite in 250 ml. water and diluting with an equal volume of ethyl alcohol. The liquid in the flask is then carefully heated so as to distil off all but about 10 ml. This is then diluted with water to 100 ml. and 10 ml. of nitric acid and an excess of a standardised solution of silver nitrate are added. The solution is then warmed to drive off the nitrous gases and to coagulate the silver chloride, and then cooled and the excess silver nitrate titrated with a solution of ammonium thiocyanate (ferric alum indicator). 

The azide value may be determined 1 shaking with dilute nitric acid until dissolved and precipitating as silver azide with excess of standard stiver nitrate. A little sodium acetate is added to decrease the solubility of the silver azide. The excess of silver nitrate is titrated with thiocyanate. The hydrazoic acid may also be distilled off after addition of acetic acid or ammonium nitrate and estimated as silver azide. 

Argentometric titration method has been applied to the determination of sulfonamide mixtures. The sulfonamides are quantitatively precipitated by the addition of excess standard silver nitrate solution, the precipitated silver salts removed by filtration, and the excess silver nitrate titrated with standard ammonium thiocyanate using ferric alum as indicator (32). 

The volume of standard ceric ammonium nitrate solution equivalent to 1 ml of ferrous ammonium sulfate solution is determined as follows. A measured portion (approximately 40 ml) of the standard ceric ammonium nitrate is placed in a 250-ml beaker and diluted to 100 ml with the dilute perchloric acid solution. Two drops of the or/ho-phenantlrroline-ferrous ammonium sulfate indicator is added, and the solution is titrated with the ferrous ammonium sulfate solution until a color change from light blue to red is produced. The volume of standard ceric ammonium nitrate solution equivalent to 1 ml of ferrous ammonium sulfate solution is calculated by dividing the volume of the former solution, which was taken for test, by the volume of the latter solution used for titration. 

To eliminate the problem caused by oxidation of the phlegmatizing agents, it is common practice to distill hydrazoic acid from the azide solution or slurry using perchloric acid. The hydrazoic acid (boiling point 35.7°C)is distilled into a known volume of standard ceric ammonium nitrate. The excess ceric ammonium nitrate is titrated with either standard ferrous ammonium sulfate or sodium... 

The titration of excess standard ceric ammonium nitrate solution after addition of azide either as a slurry, solution, or as distilled hydrazoic acid gives precise and accurate results. The ferroin endpoint is sharp and virtually instantaneous. Loss of hydrazoic acid in the distillation is apparently nil, and the reaction of hydrazoic acid with ceric ion is extremely rapid. 

Treatment of products II with BnOCOCl followed by cerium ammonium nitrate gave RNHCC Bn. e The yield was estimated by reduction with Zn/HCl and titration with NaN02-f X2 was. ... 

Ammonium nitrate (NH4NO3) is one of the most important nitrogen-containing fertilizers. Its purity can he analyzed by titrating a solution of NH4NO3 with a standard NaOH solution. In one experiment a 0.2041-g sample of industrially prepared NH4NO3 required 24.42 mL of 0.1023 M NaOH for neutralization. (a) Write a net ionic equation for the reaction, (h) What is the percent purity of the sample ... 

The stability constant of a complex of pyrophosphate with Ni (presumably NiPjO though this is not specified by the authors) was measured by an amperometric titration procedure. Small amounts of the nickel nitrate salt were titrated with the pyrophosphate in an ammonium nitrate buffer solution (0.1 M), adjusted to a pH value of 8 with aqueous ammonia. A Pb02 indicating electrode was used with a platinum foil coimter electrode and a saturated calomel reference electrode. The procedure was found to be very sensitive to pyrophosphate even in the presence of phosphate. 

Formaldehyde Titration - Method 1 (Used for Ammonium Nitrate or Suifate Nitrogen Oniy)... 

Chloride may be determined by the Volhard method. The sample is acidified with concentrated nitric acid and silver nitrate is added, which reacts with the chloride, and then the mixture is boiled. After cooling, the pale yellow solution is diluted and the excess silver nitrate titrated with potassium thiocyanate solution using ammonium ferric sulfate as indicator. The ash may also be used for this determination. 

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