hydroxidu

Hydroxidu, in many languages rendered as hydroxide, refers to compounds containing the hydroxide group (OH) or the hydroxide ion (OH−). In aqueous solutions the hydroxide ion is responsible for basicity, giving solutions a pH above 7.

Structure and properties: The hydroxide ion consists of an oxygen atom bonded to a hydrogen atom with an overall negative charge. Hydroxide is common in many metal hydroxides, which adopt varying degrees of solubility and hydrolysis behavior. Alkali metal and alkaline earth metal hydroxides differ in solubility: hydroxides of lithium, sodium, potassium, and most of the heavier alkali metals are highly soluble, while many alkaline earth hydroxides are less soluble, with solubility generally decreasing down the group.

Occurrence and production: Hydroxides occur naturally in minerals and are produced industrially by reacting metals with water or by precipitation from metal salts. The key industrial source of soluble hydroxide is through the chloralkali process, which yields sodium hydroxide (NaOH) in aqueous solution. Many hydroxides form as intermediates in chemical syntheses and are used in water treatment, paper production, and chemical manufacturing.

Reactions and applications: Hydroxides behave as bases, reacting with acids to form salts and water. Some hydroxides are amphoteric, dissolving in both acids and strong bases, such as aluminum hydroxide. Common examples include NaOH, KOH, Ca(OH)2, and Mg(OH)2. Applications span corrosion control, pH adjustment, cleaning, soap making, and the neutralization of acids.

Safety: Most hydroxides, especially strong bases like NaOH and KOH, are caustic and can cause severe burns. Proper handling, protective equipment, and ventilation are essential.