alumiinialunaattiioneja

Alumiinialunaattiioneja, also known as aluminate ions, are a group of chemical species containing aluminum and oxygen. The most common aluminate ion is the tetrahydroxoaluminate(III) ion, with the chemical formula [Al(OH)₄]⁻. This ion is formed when aluminum-containing compounds, such as aluminum hydroxide, dissolve in alkaline solutions. The aluminum atom in this ion is in the +3 oxidation state and is coordinated to four hydroxide ions.

Aluminate ions are important in various chemical processes. In the Bayer process, used for refining bauxite ore to produce alumina (aluminum oxide), aluminate ions are formed when bauxite is treated with a hot sodium hydroxide solution. The alumina dissolves as sodium aluminate, from which pure aluminum oxide is later precipitated. Aluminate ions are also found in some natural minerals and can play a role in geological processes.

In aqueous solutions, the structure and stability of aluminate ions can depend on factors like pH and concentration. Under highly alkaline conditions, [Al(OH)₄]⁻ is the predominant species. However, at lower pH values, other aluminum-oxygen species, including polynuclear ions and even aluminum hydroxide precipitates, can form. The amphoteric nature of aluminum compounds means they can react with both acids and bases, leading to the formation of various aluminum ions and complexes, including aluminates.