Arsenate Arsenic

Arsenic. Arsenic is under consideration for inclusion as an essential element. No clear role has been estabHshed, but aresenic, long thought to be a poison, may be involved in methylation of macromolecules and as an effector of methionine metaboHsm (158,160). Most research has focused on the toxicity or pharmaceutical properties of arsenic (158). 

Arsenic trioxide [1327-53-3] (arsenic(III) oxide, arsenic sesquioxide, arsenous oxide, white arsenic, arsenic), AS2O2, is the most important arsenic compound of commerce. The octahedral or cubic modification, arsenoHte [1303-24-8], 298 1313.9 kJ/mol (—314 kcal/mol) 214 J/(mol-K)... 

Arsenous arsenate [12505-65-6] (arsenic dioxide, arsenic tetroxide), AS2O4, is known and probably corresponds to As(AsO. ... 

Cyclic and Polymeric Substances Containing Arsenic—Arsenic Bonds. A number of organoarsenic compounds containing rings of four, five, or six arsenic atoms have been prepared (cycHc polyarsines). The first such four-membered ring compound to be adequately characterized, tetrakis (trifluoromethyl) tetrarsetane [7547-15-17, was obtained by the interaction of a diiodoarsine and mercury (107,108) ... 

Arsenik, m. n, arsenic, — gelber —, orpiment. — roter —, realgar. — weisser —, white arsenic, arsenic trioxide,... 

Arsenlkalien, /.pi. arsenicals, arsenical compounds or preparations, arsenikalisch, a. arsenical. 

In realgar the short non-bonding contact distances are 3.3 A for sulfur-sulfur, 3.6 A for sulfur-arsenic, and 3.5 A for arsenic-arsenic. They are accordingly about 1.2 A greater than the corresponding single-bond lengths, as found in other crystals. 

Arsenic trichloride Gallium arsenide Potassium arsenate Arsine Arsenic add Sodium arsenate Sodium arsenite CaicKjm arsenate Arsenic trioxide Arsenic pwtoxide Arsenic bisulphide Arsenic pentasulphide Arsenic hemiselenide... 

Redox reactions may cause mobile toxic ions to become either immobile or less toxic. Hexavalent chromium is mobile and highly toxic. It can be reduced to be rendered less toxic in the form of trivalent chromium sulfide by the addition of ferrous sulfate. Similarly, pentavalent (V) or trivalent (III) arsenic, arsenate or arsenite are more toxic and soluble forms. Arsenite (III) can be oxidized to As(IV). Arsenate (V) can be transformed to highly insoluble FeAs04 by the addition of ferrous sulfate. 

Arsenic Arsenic determined by cathodic stripping CSV 0.3 nmol [621]... 

Brannon and Patrick [129] reported on the transformation and fixation of arsenic V in anaerobic sediment, the long term release of natural and added arsenic, and sediment properties which affected the mobilization of arsenic V, arsenic III and organic arsenic. Arsenic in sediments was determined by extraction with various solvents according to conventional methods. Added arsenic was associated with iron and aluminium compounds. Addition of arsenic V prior to anaerobic incubation resulted in accumulation of arsenic III and organic arsenic in the interstitial water and the exchangeable phases of the anaerobic sediments. Mobilization of... 

Arsenate Arsenate reductase C. arsenatis Kraft and Macy (1998)... 

All known human carcinogens - the substances ranked by lARC as having been causally linked to human cancers - have been shown to be capable of inducing cancers in some (but not all) species of experimental animals, with the possible exception of arsenic. Arsenic is a human carcinogen, however it has not been adequately tested in animals - so it is perhaps not a real exception to the rule. A few examples of carcinogens that are known to be active in both humans and animals are presented in Table 6.4. 

ISOTOPES There are a total of 35 isotopes of arsenic, ranging from As-60 to As-92, with half-lives spanning from a few nanoseconds to 80 days. Although some references claim there are no stable isotopes of arsenic, arsenic-75 is classed as a stable isotope that makes up 100% of arsenic found in the Earth s crust. 

Synonyms and Compounds Grey arsenic metallic arsenic arsenic trichloride arsenic trioxide arsenic salts... 

Synonyms arsenic oxide arsenic sesquioxide white arsenic arsenic (III) oxide arsenious acid anhydride... 

The monohydrate, FeAs04.H20, is formed when anhydrous ferric arsenate, arsenic acid, hydrogen peroxide and water are heated in a sealed tube for 14 days at 170° C. a hemihydrate may be obtained in a similar manner by substituting precipitated ferric dihydrogen arsenate for the normal salt. 

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