Chromite ion

Chromiumflll) oxide is amphoteric. Although insoluble in water, it dissolves in acid to produce hydrated chromium ion, [Cr(H20)6] +. It dissolves in concentrated alkah to yield chromite ion. When heated with finely divided aluminum or carbon it is reduced to chromium metal ... 

Aqueous sodium hypochlorite (NaOCl household bleach) is a strong oxidizing agent that reacts with chromite ion [Cr(OH)4 ] in basic solution to yield chromate ion (Cr042-) and chloride ion. The net ionic equation is... 

The reaction is reversible on the addition of acids the precipitate dissolves. In excess reagent the precipitate dissolves readily, tetrahydroxochromate(III) ions (or chromite ions) being formed ... 

Write a balanced equation for the reaction of chromate ion, Cr04—, with stannite ion, SnfOH) —, in basic solution, to give stannate ion, Sn(OH)p—, and chromite ion, CrfOH) -. ... 

The highest oxide of chromiunTi, chromic oxide, is acidic, and forms chromates and dichromates. The lowest oxide, CrO, is basic, forming the chromous ion Cr" and its salts. Chromic hydroxide, Cr(OH)g, representing the intermediate oxidation state, is amphoteric. With acids it forms the salts of chromic ion, such as chromic sulfate. Cr2(S04)3 and with strong base it dissolves to form the chromite ion, Cr(OH)4. ... 

Oxidation states of chromium - -2, - -3, and -f-6. Oi es of chromium chronate, FeCr204, and crocoite, PbCr04. Chromium metal and its alloys ferrochrome, alloy steels, stainless steel. The aluminothermic process (Goldschrtiidt process). Electrolytic chromium. Chromium trioxide, chromic acid, dichromic acid, potassium chromate, potassium didiromate, sodium chromate, lead chromate. Equilibrium between chromate ion and dichromate ion. Chrome-tanned leather. Chromic oxide (chrome green) chromic ion, chrome alum, chromic chloride, chromic hydroxide, chromite ion. Chromous compounds. Peroxy-chromic acid. 

In basic solution, hypochlorite ions, CIO, oxidize chromite ions, Cr02, to chromate ions, Cr04, and are reduced to chloride ions. Write the balanced net ionic equation for this reaction. 

It is peculiar that in view of the similarities of AF and Cr + in their precipitation behavior as hydrous oxides these elements are widely different in their interaction with silica. One reason is that the chromite ion is not formed as easily as the aluminate ion, AlOj". The Cr ion is much larger than AF and cannot fit into the SiOj lattice to give stable anions like (SiA104)". 

Chromium ions react with excess alkali hydroxide to form green chromite ions, which are quantitatively oxidized, by excess alkali hypohromite, even at room temperature, to chromate ions ... 

Formation of the linkage isomers, [(H20)6CrNCCo(CN)5] and [(HaO)5CrCNCo-(ChOsl can be achieved using reactions (36) and (37) respectively. Base hydrolysis of these two isomers gives either (Co(CN) ] and chromite ion or chromite plus unidentified Co species respectively, ... 

When produced by such dry methods it is frequently unreactive but, if precipitated as the hydrous oxide (or hydroxide ) from aqueous chromium(III) solutions it is amphoteric. It dissolves readily in aqueous acids to give an extensive cationic chemistry based on the [Cr(H20)6] ion, and in alkalis to produce complicated, extensively hydrolysed chromate(III) species ( chromites ). 

The same mechanism proposed for the combustion catalyst Mg-chromite apply also to catalysts that allow significant yields in acetic acid from n-butane, like vanadia-titania, that accordingly also show a medium-high Brpnsied acidity. Being acetate ions intermediates in the combustion way, it is easily rationalized that the production of acetic acid is favored by the addition of steam in the reactant mixture and by adjusting the reaction conditions. 

Huge h3q)erfine magnetic fields have been observed in spinel chromites Cuo,9Nio.iCr204 and Coo,9Nio.iCr204 arising from ions in compressed tetra-... 

Lanthanum chromite is a p-type conductor so divalent ions, which act as electron acceptors on the trivalent (La3+ or Cr3+) sites, are used to increase the conductivity. As discussed above, the most common dopants are calcium and strontium on the lanthanum site. Although there is considerable scatter in the conductivities reported by different researchers due to differences in microstrucure and morpohology, the increase in conductivity with calcium doping is typically higher than that with strontium doping [4], The increase in conductivity at 700°C in air with calcium additions is shown in Figure 4.1 [1, 2, 28-44], One of the advantages of the perovskite structure is that it... 

Suzuki M, Sasaki H, and Kajimura A. Oxide ion conductivity of doped lanthanum chromite thin film interconnects. Solid State Ionics 1997 96 83-88. 

Chromite crystallization from a melt, or its re-equilibration with a melt, creates an even more reduced boundary layer at the crystal-melt interface as a consequence of the incorporation of Cr " and Fe " relative to divalent ions. The reduced conditions trigger the precipitation of IPGE minerals on the surface of crystallizing chromite that can be later on entrapped during chromite growth (Finnigan etal. 2008). 

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