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Antimony tribromide has two crystalline forms, both having orthorhombic symmetries. When a warm carbon disulfide solution of SbBr 3 is rapidly cooled, it crystallizes into the needle-like α-SbBr 3, which then slowly converts to the more stable β form. [2] Antimony tribromide hydrolyzes in water to form hydrobromic acid and antimony trioxide:
Arsenic forms colorless, odorless, crystalline oxides As 2 O 3 ("white arsenic") and As 2 O 5 which are hygroscopic and readily soluble in water to form acidic solutions. Arsenic(V) acid is a weak acid and the salts are called arsenates , [ 5 ] the most common arsenic contamination of groundwater , and a problem that affects many people.
Antimony trioxide is formed when antimony is burnt in air. [25] In the gas phase, the molecule of the compound is Sb 4 O 6, but it polymerizes upon condensing. [12] Antimony pentoxide (Sb 4 O 10) can be formed only by oxidation with concentrated nitric acid. [26] Antimony also forms a mixed-valence oxide, antimony tetroxide (Sb 2 O
Also, Lewis-acidic antimony compounds have recently been investigated to extend the chemistry of boron because of the isolobal analogy between the vacant p orbital of borane and σ*(Sb–X) orbitals of stiborane, and the similar electronegativities of antimony (2.05) and boron (2.04).
Tribromide is the anion with the chemical formula Br 3 −, or salts containing it: . Tetrabutylammonium tribromide; Tetrabromophosphonium tribromide; Pyridinium perbromide; Sodium and potassium tribromides can be prepared by reacting NaBr or KBr with aqueous bromine.
The following chart shows the solubility of various ionic compounds in water at 1 atm pressure and room temperature (approx. 25 °C, 298.15 K). "Soluble" means the ionic compound doesn't precipitate, while "slightly soluble" and "insoluble" mean that a solid will precipitate; "slightly soluble" compounds like calcium sulfate may require heat to precipitate.
Antimony metal is oxidized to antimony(III) oxide in furnaces. The reaction is exothermic. Antimony(III) oxide is formed through sublimation and recovered in bag filters. The size of the formed particles is controlled by process conditions in furnace and gas flow. The reaction can be schematically described by: 4 Sb + 3 O 2 → 2 Sb 2 O 3
Antimony is capable of displacing hydrogen from water, when heated: 2 Sb + 3 H 2 O → Sb 2 O 3 + 3 H 2. [362] It melts at 631 °C. Antimony is a semimetal with an electrical conductivity of around 3.1 × 10 4 S•cm −1 [363] and a band overlap of 0.16 eV.