Alkali
Alkalis are strongly basic substances and alkali metals (lithium to francium). Historically derived from plant ashes, industrial soda ash production moved from the Leblanc method to the Solvay (ammonia-soda) process. Sodium hydroxide (caustic soda) is made by causticizing or by brine electrolysis. Alkalis are widely used but are corrosive; immediate water irrigation and medical assessment are essential after exposure.