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Aluminium oxide is an amphoteric substance, meaning it can react with both acids and bases, such as hydrofluoric acid and sodium hydroxide, acting as an acid with a base and a base with an acid, neutralising the other and producing a salt. Al 2 O 3 + 6 HF → 2 AlF 3 + 3 H 2 O Al 2 O 3 + 2 NaOH + 3 H 2 O → 2 NaAl(OH) 4 (sodium aluminate)
Closely related are aluminium oxide hydroxide, AlO(OH), and aluminium oxide or alumina (Al 2 O 3), the latter of which is also amphoteric. These compounds together are the major components of the aluminium ore bauxite. Aluminium hydroxide also forms a gelatinous precipitate in water.
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.
A solution containing an aqua ion does not have the long-range order that would be present in a crystal containing the same ion, but there is short-range order. X-ray diffraction on solutions yields a radial distribution function from which the coordination number of the metal ion and metal-oxygen distance may be derived. With aqua ions of high ...
Al + NaOH + H 2 O → NaAlO 2 + 3 / 2 H 2. although the aluminium species in solution is probably instead the hydrated tetrahydroxoaluminate anion, [Al(OH) 4] − or [Al(H 2 O) 2 (OH) 4] −. [2] Oxidizing acids do not effectively attack high-purity aluminium because the oxide layer forms and protects the metal; aqua regia will
Sodium aluminate is an inorganic chemical that is used as an effective source of aluminium hydroxide for many industrial and technical applications. Pure sodium aluminate is a white crystalline solid having a formula variously given as NaAlO 2, NaAl(OH) 4 (), [3] Na 2 O·Al 2 O 3, or Na 2 Al 2 O 4.
As per researches conducted by V.K.Chhabra, Chief Chemist (retd.) P.H.E.D. Rajasthan, activated alumina, when used as a fluoride filter, under field conditions can best be regenerated by a solution of lye (sodium hydroxide; NaOH), sulfuric acid (H 2 SO 4). The fluoride uptake capacity (FUC) of commercial activated alumina can be up to 700 mg/kg.
Pure cryolite has a melting point of 1009 ± 1 °C (1848°F). With a small percentage of alumina dissolved in it, its melting point drops to about 1000 °C (1832°F). Besides having a relatively low melting point, cryolite is used as an electrolyte because, among other things, it also dissolves alumina well, conducts electricity, dissociates electrolytically at higher voltage than alumina, and ...