Iron: chemical compounds

FejC (also called "iron carbide" or "cementite") Complex A hard and brittle chemical compound of Fe and C containing 25 atomic % (6.7 wt%) C. 

The first large-scale use of chlorine was for bleaching paper and cotton textiles it also is widely used as a germicide for public water supplies. Presently it is used principally in production of the chemical compounds sulfur chloride, thionyl chloride, phosgene, aluminum chloride, iron(ni) chloride, titaniura(IV) chloride, tin(IV) chloride, and potassium chlorate. 

Iron control chemicals are used during acid stimulation to prevent the precipitation of iron-containing compounds. The precipitation of these compounds in the critical near-wellbore area can decrease well productivity or injectivity. Acetic acid, citric acid, NTA, EDTA, and erythorbic acid are applied [1726,1727]. A time dependence of iron (IQ) hydroxide precipitation... 

Some metals, such as iron, can form more than one type of ion. Iron ions can either have a +2 or a +3 charge. Chemists use Roman numerals to distinguish between the two different types of iron ions. The Roman numeral II in the name of the chemical compound iron(II) sulfide means that the iron ion in this compound has a +2 charge. 

The name of compounds whose molecules contain three or more elements, usually including oxygen, ends in the suffix ate. Thus the chemical name for limestone, whose chemical formula is CaC03, is calcium carbonate. That of green vitriol, also known as copperas, whose formula is FeS04, is iron sulfate. The names and formulas of some chemical compounds related to archaeological studies are listed in Table 7. 

Kunze B, Trowitzsch-Kienast W, Hofle G, Reichenbach H (1992) Nannochelins A, B and C, New Iron Chelating Compounds from Nannocystis exedens (Myxobacteria). Production, Isolation, Physico-chemical and Biological Properties. J Antibiotics 45 147... 

To a certain extent the expression multicomponent catalysts is an arbitrary one. There is no doubt that the pure chemical elements and pure chemical compounds have to be called single component catalysts. It is, however, questionable whether a material such as steel should be classified as a single component system or as a multicomponent system. Some of the multicomponent catalysts, for instance, the iron-alumina catalyst consist of two separate solid phases but it would be misleading to accept the presence of more than one phase as the decisive criterion for multicomponent catalysts. The more than additive catalytic action of Cu-ions and Fe-ions in an homogeneous aqueous medium represents obviously a case of multicomponent catalysis, although it occurs in a single-phase system. As to solid multicomponent catalysts, they usually consist of more than one single phase, but there are exceptions to this rule, such as in cases in which mixed crystals or solid solutions are formed from the components. 

Only a few metals—gold and platinum are two examples—appear in nature in metallic form. Deposits of these natural metals, also known as native metals, are quite rare. For the most part, metals are found in nature as chemical compounds. Iron, for example, is most frequently found as iron oxide, Fe203, and copper is found as chalcopyrite, CuFeS2. Geologic deposits containing relatively high concentrations of metal-containing compounds are called ores. 

Inorganic pigments are found in the earth. Iron and lead oxides provide earth colors. Copper calcium silicate and cobalt stannate provide blues. The colors burnt sienna and burnt umber come from iron oxides. Green pigments come from chromic oxide, calcinated cobalt, and zinc and aluminum oxides. Red pigments come from cadmium sulfide, cadmium selenide, and barium sulfate. All these chemical compounds come from the earth. 

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