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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 ...
A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
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.
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 ...
Tricalcium phosphate has three recognised polymorphs, the rhombohedral β form (shown above), and two high temperature forms, monoclinic α and hexagonal α′. β-Tricalcium phosphate has a crystallographic density of 3.066 g cm −3 while the high temperature forms are less dense, α-tricalcium phosphate has a density of 2.866 g cm −3 and ...
A Piper diagram is a graphic procedure proposed by Arthur M. Piper in 1944 for presenting water chemistry data to help in understanding the sources of the dissolved constituent salts in water. This procedure is based on the premise that cations and anions in water are in such amounts to assure the electroneutrality of the dissolved salts, in ...
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 ...
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 ...