Bismuth Bismuthic acid

See Bismuthic acid Hydrofluoric acid Cyanogen fluoride... 

Bismuthic acid, 0228 Boric acid, 0144 Bromic acid, 0248 Chlorosulfuric acid, 3997 Chromic acid, 4229 Diamidophosphorous acid, 4547... 

Bismuth oxide hydroxide, see Bismuthic acid, 0228 Bismuth pentafluoride, 0227 Bismuth trioxide, 0233 Bismuth trisulfide, 0234... 

Bismuth chromate , see Dibismuth dichromimu uouaoxide, 0232 Bismuthic acid, 0228 Bismuth uitride, 0230... 

Bismuthic Acid——259—ia depoaitepassed through a boUing solution of potash bolding biconuUiouB hydrate in suspension. 

Bismuthic Acid—(BiOa)H0—259—is deposited, as a red powder, when Cl is passed through a boiling solution of potash, holding Bismuthous hydroxid In suspension. When heated it is converted into the pentoxid, BiiOt. 

Remark Bi, as bismuthic acid HBiOs, is a very strong oxidant in acidic medium. It enters into the half-redox equilibrium through which the cation bismuthyle BiO+ is formed ... 

For example, bismuthic acid (metabismuthate in acidic medium) oxidizes Ce " into Ce and manganous ions into permanganate ions ... 

Crude lead contains traces of a number of metals. The desilvering of lead is considered later under silver (Chapter 14). Other metallic impurities are removed by remelting under controlled conditions when arsenic and antimony form a scum of lead(II) arsenate and antimonate on the surface while copper forms an infusible alloy which also takes up any sulphur, and also appears on the surface. The removal of bismuth, a valuable by-product, from lead is accomplished by making the crude lead the anode in an electrolytic bath consisting of a solution of lead in fluorosilicic acid. Gelatin is added so that a smooth coherent deposit of lead is obtained on the pure lead cathode when the current is passed. The impurities here (i.e. all other metals) form a sludge in the electrolytic bath and are not deposited on the cathode. 

Arsenic dissolves in concentrated nitric acid forming arsenicfV) acid, H3ASO4, but in dilute nitric acid and concentrated sulphuric acid the main product is the arsenic(III) acid, HjAsOj. The more metallic element, antimony, dissolves to form the (III) oxide Sb O, with moderately concentrated nitric acid, but the (V) oxide Sb205 (structure unknown) with the more concentrated acid. Bismuth, however, forms the salt bismulh(lll) nitrate Bi(N03)3. 5H,0. 

Very small quantities of bismuthine are obtained when a bismuth-magnesium alloy, BijMgj, is dissolved in hydrochloric acid. As would be expected, it is extremely unstable, decomposing at room temperature to bismuth and hydrogen. Alkyl and aryl derivatives, for example trimethylbismuthine, Bi(CHj)3, are more stable. 

Nitrogen is unusual in forming so many oxides. The acidity of the Group V oxides falls from phosphorus, whose oxides are acidic, through arsenic and antimony whose oxides are amphoteric, to the basic oxide ofbismuth. This change is in accordance with the change from the non-metallic element, phosphorus, to the essentially metallic element, bismuth. The +5 oxides are found, in each case, to be more acidic than the corresponding + 3 oxides. 

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