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The structure is related to that of zirconium orthosilicate (zircon): Ca 2+ is 8-coordinate, SO 2− 4 is tetrahedral, O is 3-coordinate. CaSO 4 ·2H 2 O (gypsum and selenite (mineral)): dihydrate. [7] CaSO 4 · 1 / 2 H 2 O : hemihydrate, also known as plaster of Paris. Specific hemihydrates are sometimes distinguished: α-hemihydrate ...
Gypsum is moderately water-soluble (~2.0–2.5 g/L at 25 °C) [13] and, in contrast to most other salts, it exhibits retrograde solubility, becoming less soluble at higher temperatures. When gypsum is heated in air it loses water and converts first to calcium sulfate hemihydrate ( bassanite , often simply called "plaster") and, if heated ...
Calcium bisulfite (calcium bisulphite or calcium hydrogen sulfite) is an inorganic compound which is the salt of a calcium cation and a bisulfite anion. It may be prepared by treating lime with an excess of sulfur dioxide and water.
The tetrahydrate crystallizes as a solid solution of Ca 3 (SO 3)2(SO 4). 12H 2 O and Ca 3 (SO 3)2(SO 3). 12H 2 O. The mixed sulfite-sulfate represents an intermediate in the oxidation of the sulfite to the sulfate, as is practiced in the production of gypsum. This solid solution consists of [Ca 3 (SO 3) 2 (H 2 O) 12] 2+ cations and either ...
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.
The name anhydrite was given by A. G. Werner in 1804, because of the absence of water of crystallization, as contrasted with the presence of water in gypsum. Some obsolete names for the species are muriacite and karstenite; the former, an earlier name, being given under the impression that the substance was a chloride (muriate).
The sulfur atom is in the +6 oxidation state while the four oxygen atoms are each in the −2 state. The sulfate ion carries an overall charge of −2 and it is the conjugate base of the bisulfate (or hydrogensulfate) ion, HSO − 4, which is in turn the conjugate base of H 2 SO 4, sulfuric acid.
A calcium atom has twenty electrons, with electron configuration [Ar]4s 2. Like the other elements placed in group 2 of the periodic table, calcium has two valence electrons in the outermost s-orbital, which are very easily lost in chemical reactions to form a dipositive ion with the stable electron configuration of a noble gas, in this case ...