Meaning of BASE in English


In chemistry, any substance that in water solution is slippery to the touch, tastes bitter, changes the colour of acid-base indicators (e.g., litmus paper), reacts with acid s to form salt s, and promotes certain chemical reactions (e.g., base catalysis ).

Examples of bases are the hydroxide s of the alkali metal s and alkaline earth metals ( sodium , calcium , etc.; see caustic soda ) and the water solutions of ammonia or its derivatives ( amine s). Such substances produce hydroxide ion s (OH - ) in water solutions. Broader definitions of bases cover situations in which water is not present. See also acid-base theory ; alkali ; nucleophile .

Britannica English dictionary.      Английский словарь Британика.