Potassium chromite

The chromites of the alkali metals and of ammonium are presumably formed to some extent in solution, when chromic hydroxide dissolves in excess of the alkali hydroxide but it has been shown that these solutions are in large degree merely colloidal solutions of the hydroxide (see p. 36). By shaking chromic hydroxide, dried over sulphuric acid, with solutions of sodium hydroxide of different concentrations, Muller found that the amount of hydroxide dissolved depended on the time of agitation, rising to a maximum and then falling to an almost constant value. The solutions obtained w ere not colloidal. Fricke and Wind-hausen have prepared similar solutions, and by allowing solutions of potassium chromite to stand for some time, obtained needle-shaped crystals of composition CrjOj.SKjO.SHjO. 

Cr203 green Cr(OH)3 chromium(III) hydroxide amphoteric CrCl3 anhydr. violet aq. green KCr02 green chromium (II) chloride potassium chromite... 

Manufacture The primary iadustrial compounds of chromium made directly from chromite ore are sodium chromate, sodium dichromate, and chromic acid. Secondary chromium compounds produced ia quantity include potassium dichromate, potassium chromate, and ammonium dichromate. 

Modification of the burning rates, pressure exponents, and temp coefficients of burning rate of the fluorocarbon composites has been accomplished with copper, lead, tin, sodium, ammonium and potassium fluoborates sodium, potassium, lithium, lead, copper and calcium fluorides potassium and ammonium dichromate lead and zinc stearate cesium carbonate potassium and ammonium sulfate copper chromite oxides of magnesium, copper and manganese boron zinc dust and carbon black (Ref 75)... 

In a review of the course and mechanism of the catalytic decomposition of ammonium perchlorate, the considerable effects of metal oxides in reducing the explosion temperature of the salt are described [1], Solymosi s previous work had shown reductions from 440° to about 270° by dichromium trioxide, to 260° by 10 mol% of cadmium oxide and to 200°C by 0.2% of zinc oxide. The effect of various concentrations of copper chromite , copper oxide, iron oxide and potassium permanganate on the catalysed combustion of the propellant salt was studied [2], Similar studies on the effects of compounds of 11 metals and potassium dichromate in particular, have been reported [3], Presence of calcium carbonate or calcium oxide has a stabilising effect on the salt, either alone or in admixture with polystyrene [4],... 

Chromic phosphate, molecular formula, properties, and uses, 6 563t Chromic potassium oxalate, molecular formula, properties, and uses, 6 563t Chromic potassium sulfate, molecular formula, properties, and uses, 6 563t Chromic sulfate, molecular formula, properties, and uses, 6 563t Chromite, 6 468-469, 471t consumption, 6 490-491 mining and processing, 6 477-481... 

Trivalent chromium compounds (Cr )(chromic compounds) including chromic oxide (Cr203), chromic sulfate (Ct2[S04]3), chromic chloride (CrCb), chromic potassium sulfate (KCr[S04]2), and chromite ore (FeOCdCr203). 

Potassium chromate can be made from chrome ore (chromite, Fe0 Cr203) that contains about 45% Cr20s. The ore is crushed and mixed with potassium carbonate and roasted in air or oxygen at 1,100 to 1,250°C ... 

Pure decarbonylation typically employs noble metal catalysts. Carbon supported palladium, in particular, is highly elfective for furan and CO formation.Typically, alkali carbonates are added as promoters for the palladium catalyst.The decarbonylation reaction can be carried out at reflux conditions in pure furfural (165 °C), which achieves continuous removal of CO and furan from the reactor. However, a continuous flow system at 159-162 °C gave the highest activity of 36 kg furan per gram of palladium with potassium carbonate added as promoter. In oxidative decarbonylation, gaseous furfural and steam is passed over a catalyst at high temperatures (300 00 °C). Typical catalysts are zinc-iron chromite or zinc-manganese chromite catalyst and furfural can be obtained in yields of... 

Preparation of Potassium Chromate. (Perform one experiment on each table.) Melt a mixture of 1 g of potassium carbonate, 1 gof potassium hydroxide, and 2 g of potassium nitrate in an iron crucible by heating with the flame of a burner. While stirring the melt with an iron wire, introduce 1 g of finely comminuted chromite or -0.8 g of chromium oxide into the crucible. Roast the mixture for 5-10 minutes on a blowpipe. Treat the cooled melt with water. Filter the solution and evaporate it until a crystalline film appears. What is the composition of the formed crystals Why was potassium carbonate introduced into the reaction Write the equation of the reaction. 

Although flotation was developed as a separation process for mineral processing and applies lo the sulfides of copper, lead, zinc, iron-molybdenum, cobalt, nickel, and arsenic and to nonsullides, such as phosphates, sodium chloride, potassium chloride, iron oxides, limestone, feldspar, fluorite, chromite, tungstates, silica, coal, and rhodochrosilc, flotation also applies to nonmineral separations. Flotation is used in the water disposal field, particularly in connection with petroleum waste water cleanup. 

Chromate. Potassium chromate. [CAS 7789-00-6], ICj-CrO, yellow solid, soluble, formed by reaction of potassium carbonate and chromite at a high temperature in a current of air, and then extracting with water and evaporating the solution. Used (1) as a source of chromate. (2) in leather tanning, (3) in textile dyeing, (4) in inks. 

Cycl[3,2,2]azines are also obtained from cycloaddition of indolizines with DMAD.60,201 This is illustrated by the reaction of 2-phenylindoli-zine with DMAD which gives 135. Hydrolysis with methanolic potassium hydroxide gives the corresponding acid, which can be decarboxy-lated using copper chromite. 

Salmonella typhimurium TA100, TA1535 TA98, TA1537, TA1538 Reverse mutations Base pair substitutions Frame shift mutations - - De Flora 1981 Petrilli and De Flora 1978b Chromium trichloride hexahydrate, chromium nitrite, monohydrate, chromium potassium sulfate, chromium acetate, neochromium, chromium alum, chromite... 

The preparation of potassium dichromate (Preparation 61) illustrated how chromic oxide, Cr203, can be oxidized to a chromate in which chromium exists as Cr03. For the preparation of chromic alum, it might seem as if chromic oxide or the natural chromite should yield chromic sulphate directly on treatment with sulphuric acid. This is impossible, however, because both of these substances are very resistant to the action of acids. Practically, they yield only to the action of alkaline oxidizing agents, which convert them into a chromate. Therefore potassium, or sodium, dichromates are always the products made directly from the mineral, and these serve as the materials from which other compounds of chromium are prepared. To make chromic alum from potassium dichromate it is necessary to reduce the chromium to the state of oxidation in which it originally existed in the mineral, and to add sufficient sulphuric acid to form the sulphates of potassium and... 

The deflagration of hydrazine perchlorate, both pure and with fuel and catalyst additives, has been investigated. Hydrazine perchlorate will deflagrate reproducibly if a few percent fuel is present. The deflagration process is catalyzed by copper chromite, potassium dichromate, and magnesium oxide. Deflagration rates have been measured photographically from 0.26 to 7.7 atm. A liquid layer was observed at the surface in these experiments. Vaporization rate measurements from 180°-235° C. have yielded the expression... 

Effects of Catalysts. It has been found that copper chromite, potassium dichromate, and magnesium oxide promote the deflagration of hydrazine perchlorate. Since none of these additives has any fuel content, they must be considered to be catalysts. The results of experiments with these additives are shown in Table IV. Experiments were performed both with pressed (p 1.9 grams/cc.) and tamped (p 1.1. grams/cc.) strands. 

Magnesium oxide exerts quite a different effect than do the above catalysts. Thus, less of it, 2%, is required to promote steady deflagration, but it is not capable of producing as spectacular a rate as copper chromite or potassium dichromate even in amounts as great as 10%. 

A General Description of the Hydrazine Perchlorate Deflagration Process. Let us first describe the deflagration process for hydrazine perchlorate from the above results. It is a process characterized by the formation of a molten zone which is quite turbulent and foamy it is a very erratic process, particularly for the pure material, and it is subject to very potent catalysis by copper chromite and potassium dichromate and to moderate catalysis by magnesium oxide. The process is comparatively reproducible in the presence of small amounts of fuel, and the rate obtained apparently does not depend on the nature of the fuel but only on the ambient pressure. It can be expressed by r — 0.22P where f is in cm./sec. and P in atmospheres. This corresponds to a rate, at 1 atm., some 15 times greater than that calculated by extrapolation for ammonium perchlorate (16). However the process is unstable at pressures above about 7 atm. and steady deflagration cannot be attained above this pressure. 

We attribute the effects of copper chromite, potassium dichromate, and magnesium oxide to catalysis of condensed phase reactions in view of the catalysis of the pyrolysis reaction by species of this type (11). 

Ferrous chromite, Fe0.Cr203, occurs in nature as chromite (see p. 13). It may be prepared in the laboratory by heating to a high temperature an intimate mixture of iron filings, ferrous carbonate, and potassium bichromate, covered with a thin layer of cryolite. The cooled product is extracted with water and concentrated acids in succession a residue is obtained containing chromite as small octahedra, cubo-octahedra, and cubes.7... 

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