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Crystal of potassium alum, KAl(SO 4) 2 ·12H 2 O. An alum (/ ˈ æ l ə m /) is a type of chemical compound, usually a hydrated double sulfate salt of aluminium with the general formula X Al(SO 4) 2 ·12 H 2 O, such that X is a monovalent cation such as potassium or ammonium. [1] By itself, "alum" often refers to potassium alum, with the ...
Ammonium aluminium sulfate, also known as ammonium alum or just alum (though there are many different substances also called "alum"), is a white crystalline double sulfate usually encountered as the dodecahydrate, formula (NH 4)Al(SO 4) 2 ·12H 2 O. It is used in small amounts in a variety of niche applications.
Alum-(K) is a hydrous potassium aluminium sulfate mineral with formula KAl(SO 4) 2 ·12(H 2 O). It is the mineral form of potassium alum and is referred to as potassium alum in older sources. It is a member of the alum group. [2] It occurs as colorless to white, soft isometric crystals and efflorescence coatings. [3]
in grey metallic form, each As atom has 3 neighbours in the same sheet at 251.7pm; 3 in adjacent sheet at 312.0 pm. [18] each Bi atom has 3 neighbours in the same sheet at 307.2 pm; 3 in adjacent sheet at 352.9 pm. [18] each Sb atom has 3 neighbours in the same sheet at 290.8pm; 3 in adjacent sheet at 335.5 pm. [18] puckered sheet α-Sm (none ...
The ancients are known to have used alum as a dyeing mordant and for city defense. [75] After the Crusades, alum, an indispensable good in the European fabric industry, [76] was a subject of international commerce; [77] it was imported to Europe from the eastern Mediterranean until the mid-15th century. [78] The nature of alum remained unknown.
Historically, crystal shape was defined by measuring the angles between crystal faces with a goniometer. Whereas crystals of Fe(acac) 3 are deep red and crystals of Al(acac) 3 are colorless, a solid solution of the two, i.e. Fe 1−x Al x (acac) 3 will be deep or pale pink depending on the Fe/Al ratio, x.
Alunite is a hydroxylated aluminium potassium sulfate mineral, formula K Al 3 (S O 4) 2 (OH) 6. It was first observed in the 15th century at Tolfa, near Rome, where it was mined for the manufacture of alum. First called aluminilite by J.C. Delamétherie in 1797, this name was contracted by François Beudant three decades later to alunite. [8 ...
Yttrium aluminium garnet (YAG, Y 3 Al 5 O 12) is a synthetic crystalline material of the garnet group. It is a cubic yttrium aluminium oxide phase, with other examples being YAlO 3 (YAP [2]) in a hexagonal or an orthorhombic, perovskite-like form, and the monoclinic Y 4 Al 2 O 9 (YAM [3]).