Hydrolysis of chlorides

Niobic Acid. Niobic acid, Nb20 XH2O, includes all hydrated forms of niobium pentoxide, where the degree of hydration depends on the method of preparation, age, etc. It is a white insoluble precipitate formed by acid hydrolysis of niobates that are prepared by alkaH pyrosulfate, carbonate, or hydroxide fusion base hydrolysis of niobium fluoride solutions or aqueous hydrolysis of chlorides or bromides. When it is formed in the presence of tannin, a volurninous red complex forms. Freshly precipitated niobic acid usually is coUoidal and is peptized by water washing, thus it is difficult to free from traces of electrolyte. Its properties vary with age and reactivity is noticeably diminished on standing for even a few days. It is soluble in concentrated hydrochloric and sulfuric acids but is reprecipitated on dilution and boiling and can be complexed when it is freshly made with oxaHc or tartaric acid. It is soluble in hydrofluoric acid of any concentration. 

Hydroxydehalc enation - Hydrolysis of Chlorides and Acid Chlorides... 

The properties of the borepin derivatives are discussed in Section VI. Hydrolysis of chloride. 

Fe Oj hematite hydrolysis of chloride in presence of phosphate, monodispersed ellipsoidal 25... 

Fe O vH O hydrolysis of chloride Fe20.3 H2O from nitrate FenOj-H O from nitrate Fe Oi H2O from nitrate... 

Another possibility - which we will argue later is relatively unhkely - is the assumption that in the earth s crust ammonium chloride (NH4CI) was present, which quickly and completely dissociates into NH3 and HCl with increasing temperature. The charm of this hypothesis lies in the explanation of the atmospheric HCl source (and CI2, which is formed easily via HCl photolysis). However thermal hydrolysis of chlorides which may be primordial can also explain degassing of HCl FeCl2 has been detected in meteorites. 

Such fractal materials with a large specific surface area are usually prepared by hydrolysis of chlorides or alkoxides . Fig. 18.3 shows that porosity distribution covers a very broad domain from a few angstroms to several micrometres, i.e. from the dimensions of a cationic site in a structure like 3-alumina or HUP (0.5 nm) or a zeolite cavity (0.5-2 nm) to the pores of membranes and organic polymers (5 nm-10 pm). Clays that are gels exist in the form of apparently dry powders in spite of their water content - typically 2 to 20 water molecules per mole of oxide - and are transformed by pressure sintering to objects... 

Corrosion of overhead equipment in crude distillation units is associated with HjS and with acidity from hydrolysis of chloride salts. It is controlled by neutralization to pH 6-6.5 with ammonia or an amine, plus inhibition. Similar problems may occur in other distillation units, except that hydrochloric acid may not be present. The corrosive nature of the cooling water may require use of condenser tube alloys such as titanium or copper alloys. 

This last step is carried out in order to minimize hydrolysis of chloride in the subsequent preparation of polysulphide polymers. 

Good discussion of trends in Period 3, including explanation of hydrolysis of chlorides. 

Another common fouling problem due to inorganic deposits may occur when ammonia is used to neutralize HCl formed by hydrolysis of chlorides after crude desalting. Increasing the pH, in order to reduce corrosive potential, results in formation of the oil-insoluble salt, NH4CI. This may result in a fouling problem that can be alleviated by adding water to the affected unit, either continuously or intermittently. 

Acid Corrosion. Hydrochloric acid is not present in crude oil, but it may be produced during distillation by the. hydrolysis of chloride salts, particularly magnesium chloride, that are present in the brine found in crude oils. Sulfuric acid is probably produced by the oxidation of hydrogen sulfide in the presence of moisture, but only small amounts of sulfuric acid have been detected. These acids constitute the acid corrosion that occurs in vapor lines, condensers, coolers, and rundown lines and particularly at points in which water accumulates, such as in valves in horizontal lines. 

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