alkali

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alkali

(ăl`kəlī) [Arab., al-gili=ashes of saltwort], hydroxidehydroxide
, chemical compound that contains the hydroxyl (−OH) radical. The term refers especially to inorganic compounds. Organic compounds that have the hydroxyl radical as a functional group are called alcohols; the hydroxyl radical is also present in the carboxyl group
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 of an alkali metalalkali metals,
metals found in Group 1 of the periodic table. Compared to other metals they are soft and have low melting points and densities. Alkali metals are powerful reducing agents and form univalent compounds.
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. Alkalies are readily soluble in water and form strongly basic solutions with a characteristic acrid taste. They neutralize acids, forming salts and water. Strong alkalies (e.g., those of sodium or potassium) are sometimes called caustic alkalies. The term alkali originally applied to salts obtained from plant ashes and is sometimes applied to a carbonate of sodium or potassium or to the hydroxide of an alkaline-earth metalalkaline-earth metals,
metals constituting Group 2 of the periodic table. Generally, they are softer than most other metals, react readily with water (especially when heated), and are powerful reducing agents, but they are exceeded in each of these properties by the
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.
The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Alkali

 

a base in aqueous solution. Aqueous alkaline solutions have high concentrations of OH (hydroxyl) ions. Alkalies include the hydroxides of the alkali metals, the alkaline-earth metals, and ammonium.

Most alkalies are highly hygroscopic white solid compounds. Their dissolution in water is accompanied by the liberation of large amounts of heat. Alkaline solutions change the color of acid-base indicators. The strongest, that is, caustic, alkalies are the hydroxides of the alkali metals, such as NaOH and KOH, while the weakest alkalies are ammonium hydroxide and the hydroxides of the alkaline-earth metals, such as Ca(OH)2 and Ba(OH)2. Also sometimes considered as alkalies are the salts of strong bases and weak acids (seeACIDS AND BASES), whose aqueous solutions exhibit alkaline reactions, for example, the hydro-sulfides NaSH and KSH, the carbonates Na2CO3 and K2CO3, the hydrocarbonate NaHCO3 and the borax Na2B4O7. Alkalies are commonly used in laboratory work and in industry (seeSODIUM HYDROXIDE; POTASSIUM HYDROXIDE; and CALCIUM HYDROXIDE).

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

alkali

[′al·kə‚lī]
(chemistry)
Any compound having highly basic qualities.
(petrology)
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

alkali

Any of the various chemically active bases such as the soluble salts of metals, e.g., the water-soluble salts of sodium and potassium which occur in constituents of concrete and mortar that may result in deleterious expansion.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

alkali

1. Chem a soluble base or a solution of a base
2. a soluble mineral salt that occurs in arid soils and some natural waters
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
The rate may change because of accumulation of alkalies in the solution especially silica, depresses the reaction because insoluble reaction products adhere to the surface and effectively block the reaction (Anderson and Rolen, 1987).
The principal advantages of this type of test are that it determines the total loss of material and not the alkalies alone and also that this loss is correlated to a definite surface area.
[1] reported that the slump flow increased as the alkali agent increased from 4% to 8% in liquid-to-solid ratios of 0.35, 0.40, and 0.45 in the alkali-activated ladle furnace slag geopolymer.
The present study was specifically focused on this subject, trying to demonstrate indirectly that the pozzolanic cements are able to maintain their effectiveness, as a means to minimize AAR in concrete dams, even in the cases where alkalis are supplied over a very long time, during the dam service life.
Through injecting polymer, surfactant and alkali at the same time, ASP flooding is designed to both improve displacement efficiency and expand sweep efficiency.
In Instituto Eduardo Torroja, Spain, since the early 1990s, Palomo and Puertas have studied the alkali activation of fly ash and blast furnace slag, respectively.
The compressive strength determined at 28 days was found to be 22 Mpa, 37 Mpa and 40 Mpa for specimens manufactured with 5%, 6.5% and 8% [Na.sub.2]O (alkali) respectively.
In the previous studies, the influence of main components of the mixture has been described (amount of [Na.sub.2]O, [H.sub.2]O alkali activator and fly ash).
Oceanic island rocks form two major families based on mineralogy and petrography: those that form from tholeiitic basalts and those from alkali basalts.
"Experiments in this system might give greater understanding about the alkali [condensates]," says Allan Griffin of the University of Toronto.
In this paper woven cotton fabrics were enzymatically desized, alkali and enzymatically scoured with alkali and neutral pectinases.