Iron Fe

Iron is the most abundant element on our planet, and the Earth s crust contains about 5 % of this metal, so that contamination is often a major issue in its determination. The most sensitive analytical line for iron is at 248.327 nm with a characteristic concentration of Co = 0.044 mg/L in an oxidizing air/acetylene flame, and a linear working range up to about Aokk = 1.8 mg/L. The characteristic mass at this line, using a transversely heated graphite tube atomizer, is mo = 8 pg. Iron has more than 500 absorption lines with greatly 

Iron (Fe), cobalt (Co) and nickel (Ni) are sometimes called iron group metals while ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir) and platinum (Pt) are known as platinum group metals. Metals of each group have similar physical and chemical properties. Table 2.73 sununarizes some physical properties of group-VIII metals. 

Weaver, C. Krafka, D. W. Lynch, and E. E. Koch, in Physik Daten-Optical Properties of Metals, edited by H. Behrens and G. Ebel (Fachinformationszentnun, Karlsruhe, 1981), Vol. 18-1, p. 75. 

Gullikson, and J. C. Davis, At. Data. Nucl. Data Tables 54, 181 (1993) http //henke.lbl.gov/optical constants. 

Probably the best-known battery system using an iron anode is the nickd/iron battery. It should be written (—) Fe/KOH/NiO(OH) (-t), and has its merits as a heavy duty accumulator [28]. By far less famous and much more recent are the applications of iron anodes in (rechargeable) iron/air cells [(—) Fe/K0H/02 (-t)] [29, 30] and in iron/silver oxide batteries [(—) Fe/KOH(- -LiOH)/AgO (-t)] [31, 32]. 

The precursor mixture is converted to the active iron anode either by internal reduction (AB2C2) or by high-temperature external reduction (AB2C1) [41, 42]. 

The discharge/charge of this electrode is done in two steps, but only the first step (Fe -o- Fe + + 2e ) is of practical use. For the iron/nickel oxide-hydroxide system these steps (or voltage plateaus) may be written as  

The electrochemical equivalent of iron (if only the first reduction step is taken into account) is 960 Ahkg , and the OCV of the nickel/iron ceU is 1.4 V. 

The spectral lines of the Fe atom and ions are very prominent in the spectra of stars. For this reason, coupled with its high abundance, iron has been a standard measure ofthe abundance ofheavy elements within stars. Often the ratio Fe/H, the ratio of the abundance ofiron to that of hydrogen, is taken as a measure of the metallicity of the star. It provided one of the earliestand best indications thatvery old stars within 

Natural isotopes ojiron and their solar abundances 

From the isotopic decomposition of normal iron one finds that the mass-54 isotope, 54Fe, is the second most abundant of all the ironisotopes 5.8% ofall Fe. Using thevast total abundance of elemental Fe = 9 x 105 per million silicon atoms in solar-system matter, this isotope has 

Thatis, itis 5.22% as abundantas the element silicon, making54Fe one of the abundant nuclear species. It ranks 21st in abundance among nuclei. 

The isotopes of Fe are not expected to occur in all natural samples in their usual proportions. Wide variations are expected within presolar grains but the small iron abundance within them has hindered measurements. 

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In small numbers, anodes have been made with iron (Fe), aluminium (Al), and titanium (Ti). 

An electron carries one unit of negative electrical charge (Figure 46.2). Its mass is about 1/2000 that of a proton or neutron. Therefore, very little of the mass of an atom is made from the masses of the electrons it contains, and generally the total mass of the electrons is ignored. For example, an atom of iron has a mass of 56 atomic units (au also called Daltons), of which only about 0.02% is due to the 26 electrons. Thus an iron atom (Fe ) is considered to have the same mass as a doubly charged cation of iron (Fe " ), even though there is a small mass difference. 

Atom of iron Fe°, mass approximately 56,013 from 26 protons,... 

Fig. 2. The plot of total reduced iron, Fe, and oxidized iron, Fe, normalized to Si abundance shows how the chondrite classes fall into groups distinguished by oxidation state and total Fe Si ratio. The soHd diagonal lines delineate compositions having constant total Fe Si ratios of 0.6 and 0.8. The fractionation of total Fe Si is likely the result of the relative efficiencies of accumulation of metal and siUcate materials into the meteorite parent bodies. The variation in oxidation state is the result of conditions in the solar nebula when the soHds last reacted with gas. Terms are defined in Table 1 (3).

The reduction of iron ore is accompHshed by a series of reactions that are the same as those occurring in the blast furnace stack. These include reduction by CO, H2, and, in some cases soHd carbon, through successive oxidation states to metallic iron, ie, hematite [1309-37-17, Fe202, is reduced to magnetite [1309-38-2], Fe O, which is in turn reduced to wustite [17125-56-3], FeO, and then to metallic iron, Fe. The typical reactions foUow. 

The common oxidants are ozone, hydrogen peroxide, H2O, catalyzed usually with ferrous iron, Fe , and ia some cases chlorine dioxide and uv light. Advanced oxidation systems iaclude H2O2 + uv ozone + uv and H2O2, ozone, and uv. Depending on the appHcation, the oxidation can be complete to end products as in a contaminated groundwater or partial to degradable intermediate products as in a process wastewater. 

Metal depositors. Metal-depositing bacteria oxidize ferrous iron (Fe ) to ferric iron (Fe ). Ferric hydroxide is the result. Some bacteria oxidize manganese and other metals. Gallionella bacteria, in particular, have been associated with the accumulation of iron oxides in tubercles. In fact, up to 90% of the dry weight of the cell mass can be iron hydroxide. These bacteria appear filamentous. The oxide accumulates along very fine tails or excretion stalks generated by these organisms. 

Cost iron Fe -r 1.8 to 4 C Low-stress uses cylinder blocks, drain pipes. 

Copper (Cu) and zinc (Zn), when mixed, form the alloy brass. Magnesia (MgO) and alumina (AljOj) when mixed in equal proportions form spinel. Iron (Fe) and carbon (C) mix to give carbon steel. 

Sharp Metallic Smell a) Water softener can remove 0.5 ppm or iron (Fe) for every grain/gal. of hardness up to 10 ppm at minimum pH of 6.7 (unaerated water)... 

Micronutrient An element required by plants and bacteria, in proportionately smaller amounts, for survival and growth. Micronutrients include Iron (Fe), Managanese (MN), Zinc (Zn), Boron (B), and Molybdenum (Mo). 

Example 2. The corrosion rate of silicon iron (Fe-15Si) in static H2SO4 may be predicted from ... 

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