Lead-sodium thiosulfate

Thiosulfuric Acid. Thiosulfuiic acid [14921 -76-7] is relatively unstable and thus cannot be recovered from aqueous solutions. In laboratory preparation, a lead thiosulfate [26265-65-6] solution is treated with H2S to precipitate PbS, or a concentrated solution of sodium thiosulfate [7772-98-7] is treated with HCl and cooled to — 10°C to crystalline NaCl. Aqueous solutions of thiosulfuric acid spontaneously decompose to yield sulfur, SO2, and polythionic acids, H2S O. Thiosulfuric acid is a strong acid comparable to sulfuric acid. Dissociation constants, = 0.25, = 0.018, have been... 

Sodium thiosulfate is determined by titration with standard iodine solution (37). Sulfate and sulfite are determined together by comparison of the turbidity produced when barium chloride is added after the iodine oxidation with the turbidity produced by a known quantity of sulfate iu the same volume of solution. The absence of sulfide is iadicated when the addition of alkaline lead acetate produces no color within one minute. 

A mercury manometer used with ammonia became blocked by deposition of a grey-brown solid, which exploded dining attempts to remove it mechanically or on heating. The solid appeared to be a dehydration product of Millon s base and was freely soluble in sodium thiosulfate solution. This method of cleaning is probably safer than others, but the use of mercury manometers with ammonia should be avoided as intrinsically unsafe [1,2]. Although pure dry ammonia and mercury do not react even under pressure at 340 kbar and 200° C, the presence of traces of water leads to the formation of an explosive compound, which may explode during depressurisation of the system [3], Explosions in mercury-ammonia systems had been reported previously [4,5],... 

Although silver is not treated by solvent extraction in any of the flow sheets, silver is recovered from aqueous solution in several other situations. For these processes, Cytec developed reagents with donor sulfur atoms to extract this soft element. For example, tri-isobutylphosphine sulfide (CYANEX 47IX) extracts silver from chloride, nitrate, or sulfate media selectively from copper, lead, and zinc [32]. The silver is recovered from the loaded organic phase by stripping with sodium thiosulfate, and the metal recovered by cementation or electrolysis. Silver can also be extracted from chloride solution by a dithiophosphinic acid (CYANEX 301) [33]. 

Elemental composition Pb 86.62%, O 13.38%. The compound may be identified by its physical properties and characterized by x-ray crystallography. Lead may be analyzed in the acid extract of the oxide by AA or ICP spectroscopy. It also may be analyzed by its oxidative properties. It hberates iodine from an acidic solution of potassium iodide, and the liberated iodine may be titrated against a standard solution of sodium thiosulfate using starch indicator (blue color decolorizes at the end point). 

Reaction of l,l -di(chloromercuri) ferrocene with sodium iodide or sodium thiosulfate might be expected to lead to higher homologs of XXIX in which ferrocene units are bridged by atoms of mercury. Reactions of this type have produced apparently polymeric materials with structures such as XXX, although the very limited solubility of the products has thus far precluded reliable molecular weight measurements (80). 

Supersaturation.—One of the most frequent difficulties in crystallization is due to super saturation. This condition arises when the normal saturation concentration of a salt solution is exceeded without the appearance of any crystals, and as the solution cools further it becomes steadily more supersaturated. When crystallization finally starts, it proceeds with great rapidity, forming a mass of poorly defined crystals unsuited to drying. The tendency toward supersaturation is most marked in the case of very soluble substances which form viscous or syrupy solutions. Lead acetate, sodium thiosulfate, ferric nitrate, and sulfuric acid are good examples. 

Twenty-one grams of lead nitrate are dissolved in 100ml of distilled water and mixed with 15.5g of sodium thiosulfate 5-hydrate in a similar volume of water. The white precipitate of lead thiosulfate is filtered off, washed with three 30ml portions of distilled wafer, and then twice with 20ml volumes of acetone t aid in drying. The material is dried in air. 

Used as received from Arapahoe Chemicals, Inc., Boulder, Colorado. This product, usually about 85-96% lead tetraacetate moist with acetic acid, is stored at about 5°. The molar amount specified is based on occasional iodometric titration (Arapahoe brochure) as follows 8 An accurately weighed sample of about 0.5 g. is dissolved in 5 ml. of glacial acetic acid with gentle warming, and 100 ml. of an aqueous solution of 12 g. of anhydrous sodium acetate and 1 g. of potassium iodide is added. After several minutes, with occasional swirling, the flask wall is rinsed with water. Liberated iodine is titrated with 0.LY sodium thiosulfate to a starch end point. The percent of lead tetraacetate is calculated from the formula 22.17 (milliliters of thiosulfate) (normality of thiosulfate)/(weight of sample). 

Washing with 10% aqueous sodium thiosulfate leads to a colorless organic phase, indicating total elimination of the catalyst. 

PbS20s (c). Fogh1 found <2 = 5.80 for the reaction between aqueous lead acetate and aqueous sodium thiosulfate to form an insoluble white product which was presumably lead thiosulfate. Hence, for PbS20s (c), Q/=151.1. 

Performic Acid. Contact with the nitrate may lead to explosive decomposition.8 Phenol and Trifluoroacetic Acid. Rapid exothermic reaction occurs in mixture.9 Sodium. An explosive compound is formed by interaction with Na.10 Sodium Thiosulfate or Sodium Phosphinate. Mixture explodes on heating.11... 

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