alcalin

Alcalin is a term used in chemistry to describe substances or solutions with basic properties, typically having a pH greater than 7 and the capacity to neutralize acids. In aqueous solutions, alkaline substances release hydroxide ions, which raises the pH. The term is commonly used interchangeably with alkaline, though in some contexts alkalis are defined as soluble bases that form hydroxide ions in water.

Alkalis include substances such as sodium hydroxide (NaOH) and potassium hydroxide (KOH), as well as carbonates and bicarbonates like sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3). Not all bases are soluble in water, so some bases do not produce alkaline solutions in the same way. Alkalis are used in cleaning, water treatment, agriculture, and various industrial processes due to their ability to raise pH and buffer acidity.

In geology, the term alkaline also describes rocks with high alkali metal content (potassium and sodium) relative to silica. These alkaline rocks tend to form distinctive mineral assemblages and include peralkaline and alkaline granite varieties.

Etymology: the word alcalin derives from French and Latin roots related to alkali; in English the corresponding term is alkaline. See also base, acid-base reaction, pH, alkali metal, alkaline earth metal, alkaline rocks.