Chromic arsenite

Chromic Arsenite, CrAsOg, separates as a dark green powder when a concentrated solution of pure chromic acid is boiled for some time with a saturated solution of arsenious acid. ... 

Case a, i is well illustrated by the arsenite-induced oxidation of manganese(II) by chromic acid, studied by Lang and Zwerina. The overall equation of this induced reaction is... 

In some cases, however, the modus operandi is modified. In the oxidation of hydriodic acid with chromic acid, the data indicate that while liberation of iodine takes place, the vanadous or hypovanadic salt employed as the catalyst also undergoes oxidation to vanadate.2 The vanadium compound here belongs to the class of catalysts known as inductors, and the reaction is comparable to the oxidation in aqueous solution of sodium sulphite with sodium arsenite, whereby both sodium sulphate and sodium arsenate are produced. 

Tingle x observed that a solution of arsenious oxide in aqueous alcohol, after boiling for 26 hours, was oxidised to arsenic acid, but this was denied by Edgerton.2 Kessler3 observed that when sodium arsenite was undergoing oxidation by chromic acid, oxidation by atmospheric oxygen occurred simultaneously. 

ARSENIOUS ACID or ARSENIOUS OXIDE or ARSENITE (1327-53-3) AsjOj Noncombustible solid. Reacts, possibly violently, with acids, aluminum, aluminum chloride, chlorine trifluoride, chromic oxide, fluorine, fluorides, halogens, hydrogen fluoride, mercury, oxygen fluoride, phosphorus pentoxide, rubidium acetylide, sodium chlorate, sodium hydroxide, sulfuric... 

Chemical.—Its solutions are acid in reaction, and probably contain the true arsenious acid, HjAsOa. They arc neutralized by bases, with formation of arsenites. Solutions of sodium or potassium hydroxid dissolve it, with formation of the corresponding arsenite. It is readily reduced, with separation of As, when heated with hydrogen, carbon, or potassium cyanid, and at lower temperatures by more active reducing agents. Oxidizing agents, such as HlfOj, the hydrates of chlorin, chromic acid, convert it into arsenic pentoxid or arsenic acid. Its solution, acidulated with HCl and boiled in presence of copper, deposits on the metal a gray film, composed of an alloy of Cu and As. 

The analysis method can be modified for NO analysis if, after the NO2 is first removed from the gas stream, the remaining NO is then oxidized to NO2 with soHd chromic oxide. The NO2 is then determined with arsenite as described above. This method can suffer an interference with SO2 if it is not first converted to sulfate ion (S04 ) by hydrogen peroxide prior to analysis. The method is relatively simple and inexpensive and has a reported detection limit of 2pgm. ... 

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