Ferric ions, reactions

Aaron Ortiz-Gomez, Benito Serrano-Rosales, Jesus Moreira-del-Rio, and Hugo de-Lasa, Mineralization of Phenol in an Improved Photocata lytic Process Assisted with Ferric Ions Reaction Network and Kinetic Modeling... 

Barb WG, Baxendale JH, Hargrave R (1951) Reactions of ferrous and ferric ions with hydrogen peroxide Part 2. The ferric ion reaction. Trans Faraday oc 47 591-616... 

The dependence on peroxide concentration indicated by (g) was confirmed. It is suggested that Andersen s data of Eq. (d) have been obtained at values of R2 which are not low enough to eliminate reaction (3) entirely, and hence something intermediate between first and three halves power in peroxide concentrations might be expected. However, both these sets of data show a first order dependence on ferric ion concentration and inverse first power in ([H+] + Kh) which are at variance with Eq. (g). This discrepancy has not yet been resolved, and Barb et al. suggest that other entities might be present at these high ferric ion concentrations which play no part in the ferrous ion reaction or the ferric ion reaction at lower ferric ion concentrations. 

However, the above estimate of the heat of the reaction when a hemin derivative reacts with hydrogen peroxide in a manner analogous to the ionic ferric ion reaction ... 

Mineralization of Phenol in an Improved Photocatalytic Process Assisted with Ferric Ions Reaction Network and Kinetic Modeling... 

Bromide ndIodide. The spectrophotometric determination of trace bromide concentration is based on the bromide catalysis of iodine oxidation to iodate by permanganate in acidic solution. Iodide can also be measured spectrophotometricaHy by selective oxidation to iodine by potassium peroxymonosulfate (KHSO ). The iodine reacts with colorless leucocrystal violet to produce the highly colored leucocrystal violet dye. Greater than 200 mg/L of chloride interferes with the color development. Trace concentrations of iodide are determined by its abiUty to cataly2e ceric ion reduction by arsenous acid. The reduction reaction is stopped at a specific time by the addition of ferrous ammonium sulfate. The ferrous ion is oxidi2ed to ferric ion, which then reacts with thiocyanate to produce a deep red complex. 

The ease with which the ferrous ion can be oxidized to a ferric ion in the electrowinning cell furthers this reaction. Attack on the copper is most apparent at the solution line, where it results in corrosion of the loops supporting the cathodes, leading to dropped cathodes. 

R indicates the organic portion of the resin and SO3 is the immobile portion of the ion active group. Two resin sites are needed for nickel ions with a plus 2 valence (Ni ). Trivalent ferric ions would require three resin sites. As shown, the ion exchange reaction is reversible. The degree the reaction proceeds to the right will depend on the resins preference, or selectivity, for nickel ions compared with its preference for hydrogen ions. The selectivity of a resin for a given ion is measured by the selectivity coefficient. K. which in its simplest form for the reaction... 

HSCH2CH2SH, FeCb-Si02, CH2CI2, < 1 min-7 h."" Montmorillonite Clay can also be used as a support medium for the ferric ion (75-98% yield ). In this case, the reaction is chemoselective for aldehydes."" ... 

The yield of 3-hydroxyquinoline relative to the amount of quinoline consumed is low but is increased markedly by the presence of ascorbic acid. This was attributed to the regeneration of ferrous ions by reduction of the ferric ion formed in the first step of the reaction. 

Consider the reaction you encountered in the laboratory—that between ferric ion (Fe+3) and thiocyanate ion (SCN ) ... 

Because of the presence of Cu+ ion, ferric ion is reduced. Chemists say that Cu+ ion acts as a reducing agent in this reaction—Cu+ ion is the agent that caused the reduction of ferric ion. At the same time, Cu+ is oxidized because of the presence of ferric ion. Hence, Fe+ is called an oxidizing agent in this reaction. 

Again half-reaction (70) describes what happens to ferric ion ... 

Since two electrons are gained by the two ferric ions in half-reaction (72), two electrons must be released by the remaining constituents in (71). The other half-reaction can be found by subtracting (72) from (71) to give,... 

Use oxidation numbers to balance the reaction between ferrous ion, Fe+2, and permanganate ion, MnOr, in acid solution to produce ferric ion, Fe+3, and manganous ion, Mn+2. 

The P450 reaction cycle (Scheme 10.4) starts with four stable intermediates that have been characterized by spectroscopic methods. The resting state of the enzyme is a six-coordinate, low-spin ferric state (complex I) with water (or hydroxide) coordinated trans to the cysteinate ligand. The spin state of the iron changes to high-spin upon substrate binding and results in a five-coordinate ferric ion (com-... 

NOTE It is also apparent that the ferric ion (Fe3+) should chelate most readily. In practice, however, under strongly alkaline conditions, the preferred reaction is to instantaneously form ferrous hydroxide and then to slowly revert to ferric hydroxide (competing anion effect). 

C) for cast iron and up to 140 °F for marstenitic SS (60 °C). It is widely used where silicates are present with the iron oxides. Typically, 5 to 7.5% HC1 is employed. The ammonium bifluoride normally is present at 0.5%, but it may be increased to a maximum of 1.5% for a boiler that has not been cleaned for many years. The presence of hydrofluoric acid (HF), which is formed by the reaction of ammonium bifluoride with HC1 (see equation), tends to increase the rate of iron oxide dissolution and reduce the corrosion rate of exposed steel, when compared to using HC1 alone. This is due to the stability of the hexafluoroferric ion (FeFg3 ), which prevents the ferric ion from corroding exposed steel. 

A small solvent isotope effect was found by Bell and Onwood kuiolkoiO = 1.08) in contradiction to that of only 0.38 reported by Taylor and Halpern . Over one-third of the oxygen present in the carbonate originated from the oxidant when 0-labelled permanganate was used . The reaction is subject to pronounced catalysis by ferric ions . 

H2SO3 is oxidised to two sets of products by both ferric ion and ferricyanide depending upon the reaction conditions, e.g. 

When a large excess of ferric ion was employed to promote the sulphate-forming reaction under nitrogen, it was found that a plot of versus [Fe(II)]o + 2 [H2S03]q is a straight line and in general the rate equation... 

In the presence of sufficient FeY then / i[FeY ]Ar4[FeY ] and the kinetics observed with added FeY result. Phenanthroline removes all Fe(II) from solution thereby suppressing the back-reaction in (71) and the change in order is explained. Cu(II) exerts a catalytic effect, as in the oxidation by ferric ion, by oxidising N2H3, thereby reducing the importance of the back-reaction. 

The reduction of iodine by Fe(II) is, of course, the reverse of the ferric ion-iodide ion reaction (p. 408) and it influences the kinetics of the latter. However, the direct reaction has been studied, the rate expression being ... 

Indeed, when present in concentrations sufficient to overwhelm normal antioxidant defences, ROS may be the principal mediators of lung injury (Said and Foda, 1989). These species, arising from the sequential one-electron reductions of oxygen, include the superoxide anion radical, hydrogen peroxide, hypochlorous ions and the hydroxyl radical. The latter species is thought to be formed either from superoxide in the ptesence of iron ions (Haber-Weiss reaction Junod, 1986) or from hydrogen peroxide, also catalysed by ferric ions (Fenton catalysis Kennedy et al., 1989). 

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