Alkali in Chemistry

Chemistry: Alkali and Its Etymology

• An alkali in chemistry is a basic, ionic salt of an alkali metal or an alkaline earth metal.
• It can be defined as a base that dissolves in water, resulting in a solution with a pH greater than 7.0.
• The term "alkaline" is often used as a synonym for basic, especially for bases soluble in water.
• Alkalis were the first bases known to obey the Arrhenius definition of a base and remain among the most common bases.
• The word "alkali" is derived from the Arabic "al qalīy", meaning the calcined ashes, relating to the original source of alkaline substances.
• Potash, a water-extract of burned plant ashes, was composed mostly of potassium carbonate and mildly basic.
• Heating potash with calcium hydroxide produced caustic potash (potassium hydroxide), a far more strongly basic substance.
• Caustic potash was traditionally used with animal fats to produce soft soaps in the process of saponification, known since antiquity.
• The term "alkali" likely came about because alkalis were the first bases known to obey the Arrhenius definition of a base.
• The broad use of the term "alkaline" in English likely stems from this historical significance of alkalis.
• The historical use of caustic potash and its role in soap production highlights the practical applications of alkalis.
• The etymology of "alkali" reflects its historical association with the calcined ashes and the process of obtaining alkaline substances.