alcalines

Alkalines, commonly called alkalis, are chemical bases that dissolve in water to give alkaline or basic solutions with a pH above 7. They neutralize acids to form salts and water. In aqueous solution, alkaline substances typically turn red litmus blue and may be caustic or corrosive. The term is used for soluble bases that release hydroxide ions (OH−) in water, though some basic compounds act through other mechanisms to raise pH.

Typical strong alkalis are the hydroxides of alkali metals, such as sodium hydroxide (NaOH) and potassium hydroxide (KOH). These substances dissociate completely in water and are widely used in industry. Weak alkalis include ammonia (NH3) dissolved in water, which forms ammonium and hydroxide ions but does not dissociate completely. Some soluble carbonates and bicarbonates also contribute to alkalinity in water by hydrolyzing to produce hydroxide ions, though they are not hydroxides themselves.

Alkalines have broad practical importance. They are used in chemical synthesis, soap and detergent production, paper processing, and water and soil treatment to control pH and neutralize acids. In natural environments, the term also describes substances that give soils a basic pH, often influencing nutrient availability and ecosystem health. Safety is a consideration, as many alkalis are caustic and can cause chemical burns on contact.

Overall, alkalines are a fundamental category of bases characterized by their ability to create basic aqueous solutions, their role in acid–base chemistry, and their wide range of industrial and environmental applications.