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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 ...
One particular hydrate is better known as plaster of Paris, and another occurs naturally as the mineral gypsum. It has many uses in industry. All forms are white solids that are poorly soluble in water. [5] Calcium sulfate causes permanent hardness in water.
It is mainly composed of gypsum (CaSO 4 ·2H 2 O). Although gypsum is a widely used material in the construction industry , phosphogypsum is usually not used, but is stored indefinitely because of its weak radioactivity caused by the presence of naturally occurring uranium (U) and thorium (Th), and their daughter isotopes radium (Ra), radon (Rn ...
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.
2 O) and mildly soluble gypsum (CaSO 4 ·2 H 2 O). When complete (i.e., when all Fe 2+ ions are also oxidized into less soluble Fe 3+ ions), pyrite oxidation can be globally written as follows: 2 FeS 2 + 7.5 O 2 + 4 H 2 O → Fe 2 O 3 + 4 H 2 SO 4. The sulfuric acid released by pyrite oxidation then reacts with portlandite (Ca(OH
A gypsum block is made of gypsum plaster and water. The manufacturing process [1] is automated at production plants where raw gypsum (CaSO 4 ·2H 2 O) is ground and dried, then heated to remove three-quarters of the bound water and thus transformed into calcium sulfate hemihydrate (CaSO 4 ·½H 2 O), also known as gypsum plaster, stucco, calcined gypsum or plaster of Paris.
The majority of gypsum-rich layers occur where the average annual rainfall is less than 250 mm because gypsum is moderately soluble (c. 2.6 g −1 at 25 °C) and is normally leached out under higher rainfall conditions. Gypsum cements are rarely, if ever, as strong as calcretes or silcretes. [1]
Selenite, satin spar, desert rose, and gypsum flower are crystal habit varieties of the mineral gypsum.. All varieties of gypsum, including selenite and alabaster, are composed of calcium sulfate dihydrate (meaning that it has two molecules of water), with the chemical formula CaSO 4 ·2H 2 O. Selenite contains no selenium, the similar names both derive from Greek selḗnē (σελήνη 'Moon').