Chromite formula

In an aqueous solutionchromate and dichromate ions can be interconvertible. In acid solution the unstable blue peroxo complex Chromium VI oxide peroxideCrO O 2 2is formed; it is an uncharged covalent molecule, which may be extracted into ether. Addition of pyridine results in the formation of the more stable complex CrO O 2 2 py. In aqueous solution, chromate and dichromate anions exist in a chemical equilibrium.

The predominance diagram shows that the position of the equilibrium depends on both pH and the analytical concentration of chromium. All poly oxyanions of chromium VI have structures made up of tetrahedral CrO 4 units sharing corners.

This equilibrium does not involve a change in hydrogen ion concentration, which would predict that the equilibrium is independent of pH.

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The red line on the predominance diagram is not quite horizontal due to the simultaneous equilibrium with the chromate ion. The hydrogen chromate ion may be protonated, with the formation of molecular chromic acidH 2 CrO 4but the p K a for the equilibrium.

The dichromate ion is a somewhat weaker base than the chromate ion: [4]. The chromate and dichromate ions are fairly strong oxidizing agents. In alkaline solution chromium III hydroxide is produced. The redox potential shows that chromates are weaker oxidizing agent in alkaline solution than in acid solution. Approximatelytonnestons of hexavalent chromiummainly sodium dichromate, were produced in Chromate and dichromate salts of heavy metalslanthanides and alkaline earth metals are only very slightly soluble in water and are thus used as pigments.

The lead-containing pigment chrome yellow was used for a very long time before environmental regulations discouraged its use. The primary chromium ore is the mixed metal oxide chromiteFeCr 2 O 4found as brittle metallic black crystals or granules.

Chromate and dichromate

Chromite ore is heated with a mixture of calcium carbonate and sodium carbonate in the presence of air. Subsequent leaching of this material at higher temperatures dissolves the chromates, leaving a residue of insoluble iron oxide.

Normally the chromate solution is further processed to make chromium metal, but a chromate salt may be obtained directly from the liquor. Chromate containing minerals are rare.

CrocoitePbCrO 4which can occur as spectacular long red crystals, is the most commonly found chromate mineral. Rare potassium chromate minerals and related compounds are found in the Atacama desert.Chromite forms in deep ultra-mafic magmas and is one of the first minerals to crystallize. It is because of this fact that chromite is found in some concentrated ore bodies. While the magma is slowly cooling inside the Earth's crust, chromite crsytals are forming and because of their density, fall to the bottom and are concentrated there.

Although its primary origin is ultra-mafic rocks such as peridotites, chromite is also found in metamorphic rocks such as serpentites.

Chromite, as is indicated by its early crystallization is resistant to the altering affects of high temperatures and pressures. Thus it is capable of going through the metamorphic processes unscathed, while other minerals around it are being altered to serpentinebiotite and garnets.

The Mineral chromite

This characteristic also explains chromites use as a refractory component in the bricks and linings of blast furnaces. Usually magnesium is present in chromite substituting for the iron and in fact a solid solution series exists between chromite and the much rarer mineral magnesiochromite.

All chromite specimens in nature contain some magnesium, likewise all natural magnesiochromites contain some iron.

chromite formula

Magnesiochromite is grayer in color and in streak and has a slightly lower density than chromite at a specific gravity of 4. Luster is metallic to greasy. Transparency: Crystals are opaque. Well formed crystals are rare and chromite is usually found massive or granular.

Cleavage is absent. Fracture is conchoidal. Hardness is 5. Other characteristics: Weakly magnetic and an octahedral parting is sometimes seen.

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Associated Minerals include olivinetalcserpentineuvarovitepyroxenesbiotitemagnetite and anorthite. Best Field Indicators are crystal habit, streak, associations with ultra-basic minerals and parting. View Cart. Class: Oxides and Hydroxides Group: Spinel Uses: The principle ore of chromium, as a refractory component, as a dye and as mineral specimens. This Site Awarded.Why don't fictional characters say "goodbye" when they hang up a phone?

chromite formula

If we can't tunnel through the Earth, how do we know what's at its center? All Rights Reserved. The material on this site can not be reproduced, distributed, transmitted, cached or otherwise used, except with prior written permission of Multiply.

Hottest Questions. Previously Viewed. Unanswered Questions. Metal and Alloys. What is the formula for chromium III Chromate?

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Wiki User Related Questions Asked in Chemistry What is the formula for cobalt iii chromate? It is Cr2S3. Asked in Metal and Alloys Chromium 3 sulfide formula? Asked in Metal and Alloys What is the formula for chromium nitrite? Asked in Elements and Compounds Formula for chromium bromide? Chromium II bromide is CrBr2. Asked in Elements and Compounds What are the thermal decomposition products of silver chromate?

Asked in Metal and Alloys What types of elements or what families of elements does Chromium tend to bond with? Asked in Metal and Alloys What is the formula for chromium iii thiocyanate? To balance the charges, we switch the 2 charges.

So we have 1 ion of chromium III with 3 ions of thiocyanate.

chromite formula

Asked in Elements and Compounds What information is provided by the formula for potassium chromate? The formula for potassium chromate is: K2CrO4. The formula provides the following information: there are two potassiums, 1 chromium, and 4 oxygens. CrI3 would be the formula. Trending Questions.Chromite is a mineral that is an iron chromium oxide.

Chromite Mineral Data

It has a chemical formula of FeCr 2 O 4. It is an oxide mineral belonging to the spinel group. The element magnesium can substitute for iron in variable amounts as it forms a solid solution with magnesiochromite MgCr 2 O 4. Chromite grains are commonly found in large mafic igneous intrusions such as the Bushveld in South Africa and India. Chromite is iron-black in color with a metallic lustera dark brown streak and a hardness on the Mohs scale of 5.

Chromite minerals are mainly found in mafic-ultramafic igneous intrusions and are also sometimes found in metamorphic rocks. The chromite minerals occur in layered formations that can be hundreds of kilometres long and a few meters thick.

The structure of the ore can be seen as platy, with breakages along planes of weakness. Chromite can also be presented in a thin section. The grains seen in thin sections are disseminated with crystals that are euhedral to subhedral. Chromite is a part of the spinel groupwhich means that it is able to form a complete solid solution series with other members in the same group.

Chenmingite and xieite are polymorphs of chromite while magnesiochromite and magnetite are isostructural with chromite. Chromite occurs as massive and granular crystals and very rarely as octahedral crystals. Grains of minerals are generally small in size. These grains are seen to crystallize from the liquid of a meteorite body where there are low amounts of chromium and oxygen.

The large grains are associated with stable supersaturated conditions seen from the meteorite body. Chromite is an important mineral in helping to determine the conditions that rocks form. It can have reactions with various gases such as CO and CO 2. The reaction between these gases and the solid chromite grains results in the reduction of the chromite and allows for the formation of iron and chromium alloys. There could also be a formation of metal carbides from the interaction with chromite and the gases.

Chromite is seen to form early in the crystallization process. This allows for chromite to be resistant to the alteration effects of high temperatures and pressures seen in the metamorphic series. It is able to progress through the metamorphic series unaltered.

Other minerals with a lower resistance are seen to alter in this series to minerals such as serpentinebiotite and garnet.

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Chromite is found as orthocumulate lenses of chromitite in peridotite from the Earth's mantle. It also occurs in layered ultramafic intrusive rocks. Ore deposits of chromite form as early magmatic differentiates.Its formula is CrO 4. Its overall charge is Dichromate is similar, but it contains two chromium atoms and seven oxide atoms therefore, Cr 2 O 7.

Chromate and dichromate are strongly oxidizing in acidic conditions, but weakly oxidizing in basic conditions. Chromates are generally bright yellow, while dichromates are generally orange or red.

They can be made by reaction of chromium III oxide and a metal oxide in a basic environment. They can be destroyed by reaction with reducing agents. Chromates and dichromates are harmful when powdered because the dust is carcinogenic it can cause cancer. This can be avoided by reducing chromate with something like iron II sulfate. From Wikipedia, the free encyclopedia. Chromate Systematic name. Chromate and Dichromate. Chemical formula. This short article about chemistry can be made longer.

You can help Wikipedia by adding to it. Category : Chromium compounds. Namespaces Page Talk. Views Read Change Change source View history. In other projects Wikimedia Commons. This page was last changed on 29 Decemberat See Terms of Use for details. Systematic name Chromate and Dichromate.

chromite formula

Infobox references.In an aqueous solutionchromate and dichromate ions can be interconvertible. In acid solution the unstable blue peroxo complex Chromium VI oxide peroxideCrO O 2 2is formed; it is an uncharged covalent molecule, which may be extracted into ether. Addition of pyridine results in the formation of the more stable complex CrO O 2 2 py.

In aqueous solution, chromate and dichromate anions exist in a chemical equilibrium. The predominance diagram shows that the position of the equilibrium depends on both pH and the analytical concentration of chromium. All poly oxyanions of chromium VI have structures made up of tetrahedral CrO 4 units sharing corners. This equilibrium does not involve a change in hydrogen ion concentration, which would predict that the equilibrium is independent of pH.

The red line on the predominance diagram is not quite horizontal due to the simultaneous equilibrium with the chromate ion. The hydrogen chromate ion may be protonated, with the formation of molecular chromic acidH 2 CrO 4but the p K a for the equilibrium. The dichromate ion is a somewhat weaker base than the chromate ion: [4]. The chromate and dichromate ions are fairly strong oxidizing agents.

In alkaline solution chromium III hydroxide is produced. The redox potential shows that chromates are weaker oxidizing agent in alkaline solution than in acid solution. Approximatelytonnestons of hexavalent chromiummainly sodium dichromate, were produced in Chromate and dichromate salts of heavy metalslanthanides and alkaline earth metals are only very slightly soluble in water and are thus used as pigments. The lead-containing pigment chrome yellow was used for a very long time before environmental regulations discouraged its use.

The primary chromium ore is the mixed metal oxide chromiteFeCr 2 O 4found as brittle metallic black crystals or granules.

Chromite ore is heated with a mixture of calcium carbonate and sodium carbonate in the presence of air. Subsequent leaching of this material at higher temperatures dissolves the chromates, leaving a residue of insoluble iron oxide.

Normally the chromate solution is further processed to make chromium metal, but a chromate salt may be obtained directly from the liquor. Chromate containing minerals are rare.

CrocoitePbCrO 4which can occur as spectacular long red crystals, is the most commonly found chromate mineral. Rare potassium chromate minerals and related compounds are found in the Atacama desert. All hexavalent chromium compounds are toxic due to their oxidizing power and carcinogenic IARC Group 1especially if airborne and inhaled where [ clarification needed ] they cause lung cancer.

Also positive associations have been observed between exposure to chromium VI compounds and cancer of the nose and nasal sinuses. From Wikipedia, the free encyclopedia. This article is about salts of the chromium VI anion. For other uses, see Chromate. See also for disambiguation of derived terms. Not to be confused with chromite compoundmonochromatdichromattrichromator tetrachromat. Chromate and dichromate. Chemical formula.

Chemistry of the Elements 2nd ed. A comprehensive database of published data on equilibrium constants of metal complexes and ligands. BNA Books. Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH.Chromite is an oxide mineral that an iron chromium oxide with formula: FeCr2O4. It is belonging to the spinel group. Chromite is the most important ore of chromium. Crystals are uncommon, but when found they are octahedral. Chromite is usually massive or in the form of lenses and tabular bodies, or it may be disseminated as granules.

It is sometimes found as a crystalline inclusion in diamond. Chromite is dark brown to black in color and can contain some magnesium and aluminum. Chromite is most commonly found as an accessory mineral in iron- and magnesium-rich igneous rocks or concentrated in sediments derived from them. It occurs as layers in a few igneous rocks that are especially rich in iron and magnesium.

Almost pure chromite is found in similar layers in sedimentary rocks. The layers are preserved when the sedimentary rocks metamorphose to form serpentinite. Referred to as chromitites, these rocks are the most important ores of chromium.

The weathering of chromite ore bodies can also lead to its concentration in placer deposits. Association : Olivineenstatite, plagioclaseserpentinemagnetiteilmenitepyrrhotite, pentlandite, ulvospinel. Chromite Composition: FeCr20 4. The iron may be replaced by magnesium, and the chromium by aluminum and ferric iron.

Diagnostic Features: The submetallic luster usually distinguishes chromite, but the green borax bead is diagnostic. Crystallography: Isometric; hexoctahedral. Habit octahedral. Crystals small and rare. Commonly massive, granular to compact. Environment: In metamorphic Serpentine deposits, and also in ultrabasic igneous rocks, and in placer deposits.

May also occur in meteorites. A cumulus mineral in ultramafic portions of layered mafic igneous rocks; an accessory mineral in alpine-type peridotites; also detrital.

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Common in all meteorites, except carbonaceous chondrites, and in lunar mare basalts. Chromite is a common constituent of peridotite rocks and the serpentines derived from them. One of the first minerals to separate from a cooling magma; large chromite ore deposits are thought to have been derived by such magmatic differentiation. Found only sparingly in the United States. Pennsylvania, Maryland, North Carolina, and Wyoming have produced it in the past.

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California is the only important producing state at present Also found in the Philippine Islands. The only ore of chromium. Chromium is used with various other metals to give hardness to steel, also as a plating material because of its non-corrosive nature. Chromite bricks are used to a considerable extent as linings for metallurgical furnaces, because of their neutral and refractory character. The bricks are usually made of crude chromite and coal tar but sometimes of chromite with kaolin, bauxite, or other materials.

Chromium is a constituent of certain green, yellow, orange, and red pigments and of similarly colored dyes. Rocks and minerals.


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