Acids arsenic

The complete isomorphism of arsfenic and tribasic phosphoric acids, in their salts, is one of the finest examples of isomorphism depending on similarity of constitution. Like the tiibadc phosphates, the arseniates occur in 3 forms. 

It is highly probable that phosphorus and arsenic are themselves entirely isomorphous, as elements and in one particular they are alike, besides the analogy of their compounds namely, the alliaceous odour of their vapour. 

The salts of arsenic acid give with nitrate of silver a brick-red precipitate of tribasic arseniate of silver As, 0, 3AgO and with hydrochloric acid and sulphuretted hydrogen, a pale yellow precipitate of persulphuret of arsenic. As, S,. 

No modifications of arsenic acid, analogous to bibasic and monobasic phosphoric acids, are yet known. 

Prepared by distilling 6 parts of bichloride of mercury with 1 part of metallic arsenic, 3 Hg Cl, + As, = 3 HgCl + As, Cl,. It is a colourless, volatile, fuming liquid, which is resolved, by the action of water, into hydrochloric and arsenious acids. As, Cl, + 3 HO = As, 0, + 3 H Cl. 

Write the equations for the hydrolysis of PBr3 and PBr6 respectively. 

What are the specific gravity, melting point, and boiling point of phosphorus trichloride — of phosphorus pentachloride How would you arrange an apparatus to prepare each of these compounds  

2-ounce glass-stoppered bottle, iron ring and ring stand. 

Note 1. If the residue on evaporation does not redissolve after warming it 10 minutes with 60 cc. of water, it contains arsenious oxide either from incomplete oxidation by nitric acid, or from a decomposition of arsenic pentoxide by overheating. Test 1 cc. of the suspension containing the undissolved substance by adding 10 cc. of water, then solid sodium bicarbonate until no more effervescence occurs, and then a considerable quantity in excess. Add to this a solution of iodine, drop by drop. The amount of the latter which is decolorized (if any) corresponds to the amount of arsenious acid (As203), which was in the sample. 

If arsenious acid is present it must be oxidized by further treatment with 16 N HN03 and a little HC1. 

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In Landolt -type reactions, iodate ion is reduced to iodide tlirough a sequence of steps involving a reductant species such as bisulfde ion or arsenous acid (H AsO ). The reaction proceeds through two overall... 

Florvath D and Showalter K 1995 Instabilities in propagating reaction-diffusion fronts of the iodate-arsenous acid reaction J. Chem. Rhys. 102 2471-8... 

In addition to flame fronts, which have been extensively studied experimentally, front instabilities have been investigated for the isothennal cubic autocatalytic iodate arsenous acid system [70] as well as for polymerization... 

The synthesis can be carried out with most aromatic amines and is usually termed the Skraup reaction. The nitrobenzene is frequently replaced by arsenic acid, as in the prep)aration of 8-nitroquinoline from o-nitroanUine ... 

In view of the high reactivity and sensitivity to oxidation of o-phenylone-diamine, the normal experimental conditions of the Skraup reaction are modified the condensation is carried out hi the presence of glycerol, arsenic acid solution and dilute sulphuric acid. 

The arsenic acid solution is prepared by dissolving 123 g. of arsenic pentoxide in 104 ml. of water 100 ml. of the cold solution are used in the experiment. 

H3AS04 arsenic acid H4P2O2 diphosphoric acid (or pyro-... 

Arsenic acid, H3ASO4 O.5H2O—0.5A (= V2H3ASO4 5) 15 g per liter. 

Hexafluoroarsenic acid [17068-85-8] can be prepared by the reaction of arsenic acid with hydrofluoric acid or calcium fluorosulfate (29) and with alkaH or alkaline-earth metal fluorides or fluorosulfonates (18). The hexafluoroarsenates can be prepared directly from arsenates and hydrofluoric acid, or by neutrali2ation of HAsF. The reaction of 48% HF with potassium dihydrogen arsenate(V), KH2ASO4, gives potassium hydroxypentafluoroarsenate(V)... 

Arsenic Peroxides. Arsenic peroxides have not been isolated however, elemental arsenic, and a great variety of arsenic compounds, have been found to be effective catalysts ia the epoxidation of olefins by aqueous hydrogen peroxide. Transient peroxoarsenic compounds are beheved to be iavolved ia these systems. Compounds that act as effective epoxidation catalysts iaclude arsenic trioxide, arsenic pentoxide, arsenious acid, arsenic acid, arsenic trichloride, arsenic oxychloride, triphenyl arsiae, phenylarsonic acid, and the arsenates of sodium, ammonium, and bismuth (56). To avoid having to dispose of the toxic residues of these reactions, the arsenic can be immobi1i2ed on a polystyrene resia (57). 

These precursors are prepared by reaction of fuming nitric acid in excess acetic anhydride at low temperatures with 2-furancarboxaldehyde [98-01-1] (furfural) or its diacetate (16) followed by treatment of an intermediate 2-acetoxy-2,5-dihydrofuran [63848-92-0] with pyridine (17). This process has been improved by the use of concentrated nitric acid (18,19), as well as catalytic amounts of phosphoms pentoxide, trichloride, and oxychloride (20), and sulfuric acid (21). Orthophosphoric acid, -toluenesulfonic acid, arsenic acid, boric acid, and stibonic acid, among others are useful additives for the nitration of furfural with acetyl nitrate. Hydrolysis of 5-nitro-2-furancarboxyaldehyde diacetate [92-55-7] with aqueous mineral acids provides the aldehyde which is suitable for use without additional purification. 

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. 

Monosodium methanearsonate (MSMA) [2163-80-6] CH AsONaOOH, disodium methanearsonate (DSMA) [144-21-8], CH2AsO(NaO)2, cacodyhc acid [75-60-5], (CH2)2AsOOH, and arsenic acid [7778-39-4], H AsO, are used ia agriculture appHcations (11,12). MSMA, DMSA, and cacodyUc acid are used as herbicides (qv) especially ia cotton (qv) fields for the control of Johnson and nutsedge grass and other weeds. Arsenic acid (13) and cacodyhc acid may be used as a desiccant for the defoHation of the cotton boU prior to harvesting. Calcium arsenate [7778-44-1], Ca2(As0 2> once an important chemical for the control of the boU weevil and cotton worm, has disappeared from appHcation and the use of lead arsenate [7784-40-9], Pb AsO, for fmit crops is currentiy restricted. 

Arsenous Acids and the Arsenites. Arsenous acid [13464-58-9] AsH O, is known to exist only in solution. It is a weak acid with a... 

Arsenic Acids and the Arsenates. Commercial arsenic acid, corresponds to the composition, one mole of arsenic pentoxide to four moles of water, and probably is the arsenic acid hemihydrate [7774-41-6] H AsO O.5H2O. It is obtained by treatment of arsenic trioxide with concentrated nitric acid. Solutions of this substance or of arsenic pentoxide in water behave as triprotic acids with successive dissociation constants = 5.6 x 10 , ... 

X 10 , and A3 = 3.0 x 10 . Hydrated arsenic acid loses water when heated at about 100°C with the formation of pyroarsenic acid [13453-15-1/, H4AS2O2. At higher temperatures additional water is lost to yield metaarsenic acid [10102-53-1/, HAsO. Arsenates derived from each of these acids are known. Treatment of a meta- or pyroarsenate with cold water gives the orthoarsenate. 

Arsenic pentasulfide (arsenic(V) sulfide), As S q, is stable in air up to 95°C, but at higher temperatures begins to dissociate into arsenous sulfide and sulfur. It is prepared by the fusion of arsenic with sulfur foUowed by extraction with ammonia and reprecipitation at low temperatures by addition of hydrochloric acid. Arsenic pentasulfide is precipitated at low temperatures from strongly acidic arsenate solutions by a rapid stream of hydrogen sulfide. It is hydrolyzed by boiling with water, yielding arsenous acid and sulfur. Salts derived from a number of thioarsenic acids are formed from arsenic pentasulfide and alkaH metal sulfides. 

Arsenic acid (arsenic pentoxide hydrate, arsenic V oxide hydrate, orthoarsenic acid) [12044 50-7] M 229.8 + XH2O, pKj 2.26, pK 6.76, pKj 11.29 (H3ASO4). Cryst from cone solns of... 

Amino-3-fluorophenol Arsenic acid and its salts Arsenic pentoxide Arsenic trioxide Asbestos (all types)... 

Chemical Designations - Synonyms Arsenous Acid Arsenous Acid Anhydride Arsenous Oxide Arsenic Sesquioxide White Arsenic Chemical Formula AsjOj. 

Chemical Designations - Synonyms Lead arsenate, acid Plumbous arsenate Chemical Formula PbHAS04. 

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