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The arsenate is an ion with the chemical formula AsO 3− 4. [1] Bonding in arsenate consists of a central arsenic atom, with oxidation state +5, double bonded to one oxygen atom and single bonded to a further three oxygen atoms. [2] The four oxygen atoms orient around the arsenic atom in a tetrahedral geometry. [2]
Arsenic acid or arsoric acid is the chemical compound with the formula H 3 AsO 4. More descriptively written as AsO(OH) 3, this colorless acid is the arsenic analogue of phosphoric acid. Arsenate and phosphate salts behave very similarly. Arsenic acid as such has not been isolated, but is only found in solution, where it is largely ionized.
The protonation steps between the arsenate and arsenic acid are similar to those between phosphate and phosphoric acid. Unlike phosphorous acid, arsenous acid is genuinely tribasic, with the formula As(OH) 3. [5] A broad variety of sulfur compounds of arsenic are known.
The researchers conjectured that historically these photosynthesizing organisms produced the arsenates that allowed the arsenate-reducing bacteria to thrive. [14] In humans, arsenite inhibits pyruvate dehydrogenase (PDH complex) in the pyruvate-acetyl CoA reaction, by binding to the –SH group of lipoamide, a participant coenzyme.
Arsenate (+5 oxidation state) is the dominant form of arsenic in surface water, while arsenite (+3 oxidation state) is the dominant form in hypoxic to anoxic environments. Arsenite is more soluble and mobile than arsenate. Many species of bacteria can transform arsenite to arsenate in anoxic conditions by using arsenite as an electron donor. [189]
The group 1 alkali metals and the group 2, alkaline earth metals, form arsenides with isolated arsenic atoms.They form upon heating arsenic powder with excess sodium gives sodium arsenide (Na 3 As).
Calcium arsenate is commonly prepared from disodium hydrogen arsenate and calcium chloride: 2 Na 2 H[AsO 4] + 3 CaCl 2 → 4 NaCl + Ca 3 [AsO 4] 2 + 2 HCl. In the 1920s, it was made in large vats by mixing calcium oxide and arsenic oxide. [6] In the United States, 1360 metric tons were produced in 1919, 4540 in 1920, and 7270 in 1922. [1]
An arsenate arsenite is a chemical compound or salt that contains arsenate and arsenite anions (AsO 3 3-and AsO 4 3-). These are mixed anion compounds or mixed valence compounds. Some have third anions. Most known substances are minerals, but a few artificial arsenate arsenite compounds have been made. Many of the minerals are in the Hematolite ...