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/as"id/, n.1. Chem. a compound usually having a sour taste and capable of neutralizing alkalis and reddening blue litmus paper, containing hydrogen that can be replaced by a metal or an electropositive group to form a salt, or containing an atom that can accept a pair of electrons from a base. Acids are proton donors that yield hydronium ions in water solution, or electron-pair acceptors that combine with electron-pair donors or bases.2. a substance with a sour taste.3. something, as a remark or piece of writing, that is sharp, sour, or ill-natured: His criticism was pure acid.5. put on the acid, Australian Slang. to importune someone, as for money, sexual favors, or confidential information.adj.6. Chem.a. belonging or pertaining to acids or the anhydrides of acids.b. having only a part of the hydrogen of an acid replaced by a metal or its equivalent: an acid phosphate.7. sharp or biting to the taste; tasting like vinegar; sour: acid fruits.8. sharp, biting, or ill-natured in mood, manner, etc.: an acid remark; an acid wit.9. Geol. containing much silica.10. Metall. noting, pertaining to, or made by a process in which the lining of the furnace, or the slag that is present, functions as an acid in high-temperature reactions in taking electrons from oxide ions: usually a siliceous material, as sand or ganister. Cf. basic (def. 3).[1620-30; < L acidus sour, akin to acer sharp, acetum vinegar, ACESCENT, ACICULA]Syn. 8. acerbic, stinging, vitriolic, tart. ACID, ASTRINGENT are terms used figuratively of wit or humor. ACID suggests a sharp, biting, or ill-natured quality: an acid joke about an opponent. ASTRINGENT connotes severity but usually also a bracing quality, as of something applied with curative intent: astringent criticism.
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IAny substance that in water solution tastes sour, changes the colour of acid-base indicators (e.g., litmus), reacts with some metals (e.g., iron) to yield hydrogen gas, reacts with bases to form salts, and promotes certain chemical reactions (e.g., acid catalysis).Acids contain one or more hydrogen atoms that, in solution, dissociate as positively charged hydrogen ions. Inorganic, or mineral, acids include sulfuric acid, nitric acid, hydrochloric acid, and phosphoric acid. Organic acids include carboxylic acids, phenols, and sulfonic acids. Broader definitions of acids cover situations in which water is not present. See also acid-base theory.II(as used in expressions)acid base theory* * *
any substance that in water solution tastes sour, changes the colour of certain indicators (e.g., reddens blue litmus paper), reacts with some metals (e.g., iron) to liberate hydrogen, reacts with bases to form salts, and promotes certain chemical reactions (acid catalysis). Examples of acids include the inorganic substances known as the mineral acids—sulfuric, nitric, hydrochloric, and phosphoric acids—and the organic compounds belonging to the carboxylic acid, sulfonic acid, and phenol groups. Such substances contain one or more hydrogen atoms that, in solution, are released as positively charged hydrogen ions (see Arrhenius theory).Broader definitions of an acid, to include substances that exhibit typical acidic behaviour as pure compounds or when dissolved in solvents other than water, are given by the Brønsted–Lowry theory (q.v.) and the Lewis theory (q.v.). Examples of nonaqueous acids are sulfur trioxide, aluminum chloride, and boron trifluoride. Compare base.* * *
Universalium. 2010.
