Alkalii

Alkalii is a term that appears in some languages and historical contexts to denote substances with alkaline properties, most often the alkalis—soluble bases that form hydroxide ions in water. In contemporary English, the standard term is alkali, and alkalii may be encountered mainly in translations, older scientific writings, or petrochemical and industrial glossaries. The underlying idea traces back to the Arabic al-qaly, meaning ashes used for potash, and it entered European science through medieval and early modern chemical literature.

Classification and properties: The core members of the alkalii concept are the hydroxides of alkali metals, such as lithium hydroxide (LiOH), sodium hydroxide (NaOH), potassium hydroxide (KOH), and their heavier congeners. These substances are typically highly soluble in water and yield strongly alkaline solutions with pH well above 7. They are highly reactive with acids and can react with carbon dioxide in the air to form carbonates or bicarbonates. Some sources extend the term to include other soluble bases and related alkaline substances, while sparing insoluble alkaline earth bases, which are described separately as alkaline earth hydroxides or bases.

Uses and applications: Alkali materials are central to many industrial processes, including soap making, paper production, chemical synthesis, cleaning and drain regents, and water treatment. They are also used in laboratory settings as strong bases and reactants in neutralization reactions.

Safety and handling: Alkalis are caustic and can cause severe chemical burns on skin and eye contact. They react vigorously with acids and moisture; protective equipment and proper storage in sealed containers are essential. Storage should prevent moisture uptake and minimize exposure to carbon dioxide and heat sources.

Note: The preferred English term for these substances is alkali; alkalii appears mainly in non-English sources or historical discussions.