Ferric sulphate

Detection Corrosive waters formed by these bacteria have a pH in the region of 2 to 3, show a brown deposit of basic ferric sulphate, and contain free sulphuric acid. 

The furnace scales which form on alloy steels are thin, adherent, complex in composition, and more difficult to remove than scale from non-alloy steels. Several mixed acid pickles have been recommended for stainless steel, the type of pickle depending on the composition and thickness of the scale For lightly-scaled stainless steel, a nitric/hydrofluoric acid mixture is suitable, the ratio of the acids being varied to suit the type of scale. An increase in the ratio of hydrofluoric acid to nitric acid increases the whitening effect, but also increases the metal loss. Strict chemical control of this mixture is necessary, since it tends to pit the steel when the acid is nearing exhaustion. For heavy scale, two separate pickles are often used. The first conditions the scale and the second removes it. For example, a sulphuric/hydrochloric mixture is recommended as a scale conditioner on heavily scaled chromium steels, and a nitric/hydrochloric mixture for scale removal. A ferric sulphate/ hydrofluoric acid mixture has advantages over a nitric/hydrofluoric acid mixture in that the loss of metal is reduced and the pickling time is shorter, but strict chemical control of the bath is necessary. 

Acid ferric- sulphate (Streicher) test n 50wt.% H2SO4 -1-25 g/l ferric sulphate 120 h exposure to boiling solution Mass loss per unit area -1- 0-7 to -1- 0-9 1. Chromium-depleted areas 2. <7-phase in some alloys... 

A determination of dimethyl sulphoxide by Dizdar and Idjakovic" is based on the fact that it can cause changes in the visible absorption spectra of some metal compounds, especially transition metals, in aqueous solution. In these solutions water and sulphoxide evidently compete for places in the coordination sphere of the metal ions. The authors found the effect to be largest with ammonium ferric sulphate, (NH4)2S04 Fe2(S04)3T2H20, in dilute acid and related the observed increase in absorption at 410 nm with the concentration of dimethyl sulphoxide. Neither sulphide nor sulphone interfered. Toma and coworkers described a method, which may bear a relation to this group displacement in a sphere of coordination. They reacted sulphoxides (also cyanides and carbon monoxide) with excess sodium aquapentacyanoferrate" (the corresponding amminopentacyanoferrate complex was used) with which a 1 1 complex is formed. In the sulphoxide determination they then titrated spectrophotometrically with methylpyrazinium iodide, the cation of which reacts with the unused ferrate" complex to give a deep blue ion combination product (absorption maximum at 658 nm). 

Ferric sulphate is a mild oxidant and is non-reactive with the steroid substrate. It liberates iodine quantitatively (equation 76), and the iodine is extracted into CH2CI2 and consumed as in equation 75. 

Cram and Day 57> successfully synthesized a quinone of [2.2]para-cyclophane by coupling the phenol 148 with diazotized sulphanilic acid to give 149. Reduction of 149 gave the unstable aminophenol 150 on oxidation with ferric sulphate 150 afforded the quinone 30 in 68% overall yield. 

Coagulants/ Flocculants Ferric chloride, ferric sulphate, polyelectrolytes... 

Acetamido-2-deoxy-D-glucose (General Alcoholysis) a-Pyranosides prevalent at equilibrium P-pyranosides present to large extent before final equilibration or if ferric sulphate used as catalyst Ferric suphate may act as a catalyst with valuable specificities in glycosidations 18)... 

Chemical leaching of pyrite has been accomplished with aqueous ferric sulphate under pressure. The overall reaction is... 

Fe source was ferric sulphate for other zeolites ferric nitrate was used, e Si/Al in L and Y zeolites varied in the range 4-5 and 2.3-3 respectively. The other ferrisilicates were substantially free from Al. 

On the other hand, sulphates of tervalent metals dissociate easily. The old process for the preparation of H2S04 was based on the dissociation of ferric sulphate, the SOs being absorbed in moderately dilute sulphuric acid. In this manner fuming sulphuric, or Nord-hausen, acid can be prepared. 

Ammonium ferric sulphate (I2H2O) [7783-83-7] M 482.2. Crystd from aqueous ethanol. 

Ferric sulphate (XH2O) [10028-22-5] M 399.9 + XH2O. Dissolve in the minimum volume of dilute aqueous H2SO4 and allow to evaporate at room temp until crystals start to form. Do not concentrate by boiling off the H2O as basic salts will be formed. Various hydrates are formed the common ones are the dodeca and nona hydrates which are violet in colour. The anhydrous salt is colourless and very hygroscopic but dissolves in H2O slowly unless ferrous sulphate is added. 

The solid contents were obtained by evaporating to dryness and weighing. The various constituents were separated first by extraction with alcohol, thus dissolving chlorides and nitrates of calcium, magnesia, and barium if that were present, and sometimes ferric sulphate (dephlogisti-cated martial vitriol). 

Preparation.—(1) At one time fuming sulphuric acid was largely prepared by the dry distillation of basic ferric sulphate which had been obtained by submitting ferrous sulphate to atmospheric oxidation and subsequently dehydrating the oxidation product fairly completely ... 

The quantitative effect of various additives on the rate of separation of nitroglycerine from spent add has been determined by Moisak and Grigoryev [15]. They found that in the presence of 0.5% ferric sulphate or lead sulphate, the separation rate is halved. Further, they established that the separation rate is related to the composition of the spent acid. The maximum rate of separating was achieved by using add composed as follows ... 

Oleum.—Oleum is supplied in all strengths up to 70% free S03. From 0—40% free S03 it is liquid from 40—60% free S03 it is solid from 60—70% free S03 it is liquid above 70% it is solid. The acid should be kept in well-stoppered, stout glass bottles, and when it is necessary to melt the acid, the stopper is withdrawn, a watch-glass placed on the mouth of the bottle, and the bottle placed on a layer of sand in a large vessel or oil bath which is warmed with a small flame. The bottle is fitted with a wash-bottle attachment, and any desired quantity is forced out by gentle air pressure from hand or foot bellows (the mouth must not be used). For the preparation of oleum of definite strengths, see p. 314. Usual impurities ferric sulphate, sulphur dioxide and lead sulphate. For estimation, see p. 313. 

The precipitate (tannate of iron) is dissolved in dilute sulphuric add and the solution thus obtained extracted with ethyl acetate, the ethereal liquid being then separated from the aqueous solution and evaporated to dryness. The residue (tannic add) is dissolved in water and identified by means of dilute ferric sulphate or ferric alum solution (blackish-blue coloration). If the ink contains logwood, part of this passes with the tannin in such case, to identify the tannin in the aqueous solution of the ethyl acetate extract, distinctly alkaline ammoniacal copper sulphate is added, this giving a pretipitate in presence of tannin. 

The difference between these two amounts (as SO,) is diminished by 014% (referred to leather with the normal amount of moisture), this being the mean quantity of SO, formed, during the determination of the total sulphuric acid, by the oxidation of the sulphur in the hide substance. It scarcely needs mention that, when aluminium, chromium and ferric sulphates are present, these lose sulphuric anhydride during the determination of the combined sulphuric acid and are converted into oxides. To obtain exact results in this case, it is necessary to ignite strongly to complete decomposition of these sulphates, to estimate the three oxides in the ash and to subtract from the resultant free sulphuric add also the SO, corresponding with the oxides thus found. 

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