acid

1. A compound yielding a hydrogen ion in a polar solvent ( e.g., in water); acids form salts by replacing all or part of the ionizable hydrogen with an electropositive element or radical. 2. In popular language, any chemical compound that has a sour taste (given by the hydrogen ion). 3. Sour; sharp to the taste. 4. Relating to a.; giving an a. reaction. For individual acids, see specific names. [L. acidus, sour]

- bile acids steroid acids found in bile; e.g., taurocholic and glycocholic acids, used therapeutically when biliary secretion is inadequate and for biliary colic. Their physiologic roles include fat emulsification. Their synthesis is reduced in disorders of the peroxisomes.

- Brøonsted a. an a. that is a proton donor.

- conjugate a. the protonated compound of two compounds that differ in structure only by the presence of the labile proton.

- dibasic a. an a. containing two ionizable atoms of hydrogen in the molecule. See a. (1).

- fatty a. fatty a..

- inorganic a. an a. made up of molecules not containing organic radicals; e.g., HCl, H₂SO₄, H₃PO₄.

- Lewis a. an a. that is an electron pair acceptor.

- monobasic a. an a. containing one ionizable atom of hydrogen in the molecule. See a. (1).

- organic a. an a. made up of molecules containing organic radicals; e.g., acetic a., citric a., which contain the ionizable —COOH group.

- polybasic a. an a. containing more than three ionizable atoms of hydrogen in the molecule. See a. (1).

- wax a. a long-chain monocarboxylic a. with an even number of carbons, often found esterified in waxes ( e.g., lauric a.).

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Arithmetic, Coding, Information, and Digit Span

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ac·id 'as-əd adj

1) sour, sharp, or biting to the taste

2 a) of, relating to, or being an acid also having the reactions or characteristics of an acid <an \acid solution>

b) of salts and esters derived by partial exchange of replaceable hydrogen <\acid sodium carbonate NaHCO₃>

c) marked by or resulting from an abnormally high concentration of acid <\acid indigestion> not used technically

acid n

1) a sour substance specif any of various typically water-soluble and sour compounds that in solution are capable of reacting with a base to form a salt, that redden litmus, that have a pH less than 7, and that are hydrogen-containing molecules or ions able to give up a proton to a base or are substances able to accept an unshared pair of electrons from a base

2) LSD

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ac·id (asґid) [L. acidum from acidus sharp, sour] any of a large class of chemical substances defined by three chemical concepts of increasing generality. An Arrhenius acid is a substance that lowers the pH (increases the hydrogen ion concentration) when added to an aqueous solution; such substances have a sour taste, turn litmus red, and react with alkalis to form salts. A Bronsted-Lowry acid is a species that acts as a proton donor in solution; e.g., the ammonium ion (NH₄⁺) can donate a proton, leaving ammonia (NH₃); such species are termed conjugate acid-base pairs. A Lewis acid is a species that can accept a pair of electrons to form a covalent bond; e.g., BF₃ in the reaction BF₃ + NH₃ → BF₃NH₃. Aqueous solutions of certain compounds that dissociate in solution, e.g., hydrogen chloride, are designated acids by names beginning with hydro-, e.g., hydrochloric acid. Most other common inorganic acids are oxo acids (q.v.); common organic acids include carboxylic acids, sulfonic acids, and phenols. The name of the anion formed by the removal of hydrogen from an acid (its conjugate base) and the names of salts and esters of acids are formed by removing the suffix -ic and the word acid and adding the suffix -ate, except for oxo acids ending in -ous, when the suffix is -ite. For particular acids, see the specific name.