Hydrochloric acid solutions

JiVith ammoniacal or hydrochloric acid solution of copper(I) chloride, carbon monoxide forms the addition compound CuCl. CO. 2H2O. This reaction can be used to quantitatively remove carbon monoxide from gaseous mixtures. 

In concentrated hydrochloric acid solution, the reaction is GeCl -p Cr [GeClj]-and salts of this anion are known. 

If an appreciable amount of residue remains, note its colour. Add a few drops of water and test the solution (or suspension) with htmus or with Universal indicator paper. Then add a httle dilute hydrochloric acid and observe whether efiervesceiice occurs and the residue dissolves. Apply a flame test with a platinum wire on the hydrochloric acid solution to determine the metal present. (In rare cases, it may be necessary to subject a solution of the residue to the methods of qualitative inorganic analysis to identify the metal or metals present.) If the flame test indicates sodium, repeat the ignition of the substance on platinum foil. 

Analyses of alloys or ores for hafnium by plasma emission atomic absorption spectroscopy, optical emission spectroscopy (qv), mass spectrometry (qv), x-ray spectroscopy (see X-ray technology), and neutron activation are possible without prior separation of hafnium (19). Alternatively, the combined hafnium and zirconium content can be separated from the sample by fusing the sample with sodium hydroxide, separating silica if present, and precipitating with mandelic acid from a dilute hydrochloric acid solution (20). The precipitate is ignited to oxide which is analy2ed by x-ray or emission spectroscopy to determine the relative proportion of each oxide. 

Hydrogen Chloride—Water System. Hydrogen chloride is highly soluble in water and this aqueous solution does not obey Henry s law at ah concentrations. Solubhity data are summarized in Table 5. The relationship between the pressure and vapor composition of unsaturated aqueous hydrochloric acid solutions is given in Reference 12. The vapor—Hquid equiHbria for the water—hydrogen chloride system at pressures up to 1632 kPa and at temperatures ranging from —10 to +70° C are documented in Reference 13. 

Nuclear Waste Reprocessing. Liquid waste remaining from processing of spent reactor fuel for military plutonium production is typically acidic and contains substantial transuranic residues. The cleanup of such waste in 1996 is a higher priority than military plutonium processing. Cleanup requires removal of long-Hved actinides from nitric or hydrochloric acid solutions. The transuranium extraction (Tmex) process has been developed for... 

A widely used procedure for determining trace amounts of tellurium involves separating tellurium in (1 1) hydrochloric acid solution by reduction to elemental tellurium using arsenic as a carrier and hypophosphorous acid as reductant. The arsenic, reduced from an addition of arsenite to the solution, acts as a carrier for the tellurium. The precipitated tellurium, together with the carrier, is collected by filtration and the filter examined directly in the wavelength-dispersive x-ray fluorescence spectrometer. 

The existence of anhydrothiosulfuric acid [83682-21-7] has been proposed to explain the apparent stabiUty of thiosulfate in concentrated hydrochloric acid solution (16) ... 

The only known trivalent tungsten complex is of the type M(I)2(W2Cl2). It is prepared by the reduction of strong hydrochloric acid solutions of K2WO4 with tin. If the reduction is not sufficient, a compound containing tetravalent tungsten, K2(WCl (OH)) [84238-10-0] is formed (57). 

The pH is measured colorimetricaHy with phenol red indicator. High FAC causes lower pH rea dings due to bleaching of the indicator and resultant HCl formation. The pH of pool water is readily controlled with inexpensive chemicals. Hydrochloric acid solution or sodium bisulfate lower it, whereas sodium carbonate raises it. Since acid addition neutralizes a portion of the alkalinity, this must be replenished if the alkalinity drops below the minimum. By contrast, pH adjustment with carbon dioxide does not affect alkalinity. 

Tetragonal prisms of ZrOCl2 -8H2 0 crystallize from hot hydrochloric acid solutions by cooling or by increasing the acidity in >32% hydrochloric acid transparent hexagonal plates are formed probably as ZrOCl2-2HClT0H2O (198). 

Arsonium salts have found considerable use in analytical chemistry. One such use involves the extraction of a metal complex in aqueous solution with tetraphenyiarsonium chloride in an organic solvent. Titanium(IV) thiocyanate [35787-79-2] (157) and copper(II) thiocyanate [15192-76-4] (158) in hydrochloric acid solution have been extracted using tetraphenyiarsonium chloride in chloroform solution in this manner, and the Ti(IV) and Cu(II) thiocyanates deterrnined spectrophotometricaHy. Cobalt, palladium, tungsten, niobium, and molybdenum have been deterrnined in a similar manner. In addition to their use for the deterrnination of metals, anions such as perchlorate and perrhenate have been deterrnined as arsonium salts. Tetraphenyiarsonium permanganate is the only known insoluble salt of this anion. 

Chlorate Analysis. Chlorate ion concentration is determined by reaction with a reducing agent. Ferrous sulfate is preferred for quaHty control (111), but other reagents, such as arsenious acid, stannous chloride, and potassium iodide, have also been used (112). When ferrous sulfate is used, a measured excess of the reagent is added to a strong hydrochloric acid solution of the chlorate for reduction, after which the excess ferrous sulfate is titrated with an oxidant, usually potassium permanganate or potassium dichromate. 

Petroleum. Citric acid is added to hydrochloric acid solutions in acidising limestone formations. Citric acid prevents the formation of ferric hydroxide gel in the spent acid solution by chelating the ferric ions present. Formation of the gel would plug the pores, preventing the flow of oil to the producer well (123—127). 

Dichloroanthraquinone [82-46-2] (46) is an important iatermediate for vat dyes and disperse blue dyes. Examples are Cl Vat Violet 13 [4424-87-7] (170), Cl Vat Orange 15 [2379-78-4] (154), and Cl Disperse Blue 56 [31810-89-6] (11). 1,5-DichloroantliraquiQone is prepared by the reaction of anthraquiQone-l,5-disulfonic acid with NaClO iu hot hydrochloric acid solution. Alternative methods from 1,5-dinitroanthraquiaone (49) by reaction of chlorine at high temperature ia the presence of phthaUc anhydride have been proposed (66). 

The second important class of sorbents on CMSG basis for noble metal concentration are anion-exchangers, that is predetermined by their presence as acidocomplexes in hydrochloric acid solutions. 

Aluminum corrodes at a fairly low rate between a pH of 5.5 and 8.5 at room temperature. At concentrations between 50% and 95%, sulfuric acid causes rapid attack below 10%, corrosion is much less. Hydrochloric acid is quite corrosive in all but dilute concentrations. The corrosion rate in hydrochloric acid increases 100-fold as temperature increases from 50°F (10°C) to 176°F (80°C) in a 10% hydrochloric acid solution. 

Heating of the cyclic polymer at 250°C will also lead to the production of the linear polymer, which is rubbery and stable to 350°C. On standing, however, the material hydrolyses and after a few day loses its elastic properties and becomes hard and covered with drops of hydrochloric acid solution. 

Chemical Reactivity - Reactivity with Water Reacts vigorously as an exothermic reaction. Forms beryllium oxide and hydrochloric acid solution Reactivity with Common Materials Corrodes most metals in the presence of moisture. Flammable and explosive hydrogen gas may collect in confined spaces Stability During Transport Stable Neutralizing Agents for Acids and Caustics Flush with water and rinse with dilute solution of sodium bicarbonate or soda ash Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

BrCl can be prepared by the reaction in the gas phase or in aqueous hydrochloric acid solution. In the laboratory, BrCl is prepared by oxidizing bromide salt in a solution containing hydrochloric acid. 

The largest protonated cluster of water molecules yet definitively characterized is the discrete unit lHi306l formed serendipitously when the cage compound [(CyHin)3(NH)2Cll Cl was crystallized from a 10% aqueous hydrochloric acid solution. The structure of the cage cation is shown in Fig. 14.14 and the unit cell contains 4 [C9H,8)3(NH)2aiCUHnOfiiai- The hydrated proton features a short. symmetrical O-H-0 bond at the centre of symmetry und 4 longer unsymmetrical O-H - 0 bonds to 4... 

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