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 It might be outdated or ideologically biased.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 ?
AMAI represents the entire alkali industry and prominent PVC resin manufacturers in the country.
Sambo Alkali then stated that the disease can be contacted through repeated contact with an untreated person for a long period of time, adding once a case is detected, the person should be taken to the nearest leprosy treatment centre to prevent further spread of the disease.
The Plateau State Police Command has said that Da Yakubu Rap, one of the persons declared wanted for their alleged involvement in the killing of the Major General IM Alkali, (retired) has surrendered himself to the command.
Sachlo is one of the largest manufacturers of chlor alkali and chlorine derivatives in Saudi Arabia.
In order to forecast the effectiveness of pozzolanic cements, even in the very long-term prevention of AAR, it is essential to verify if these cements are able to incorporate, besides the alkali already present and available in the concrete from the beginning, also those that may become available over time, after decades, due to the slow internal alkali supply.
The impermeable film around BFS is destroyed by the alkali activation of O[H.sup.-] ions, and hydration reaction occurs to produce hydration products such as xCaO-ySi[O.sub.2]-z[H.sub.2]O and xCaO-y[Al.sub.2][O.sub.3]-z[H.sub.2]O [30-32].
A total of 60 New Zealand rabbits (2.0-2.5 kg) were purchased from Zunyi Laboratorial Animal Center, Chinese Academy of Sciences and randomly separated into six groups: Group A was injured with alkali burns to induce CNV and given no treatment; Groups B, C, and D were administered CXL for 30 min, 15 min, and 45 min immediately after injury, respectively; and Groups E and F were administered CXL for 30 min after 1 day and 3 days injury, respectively.
Acidic, alkali, and sequential acidic-alkali pretreatments, combined with high temperature or high pressure, have been applied in "conventional" chemical treatment processes [3-5, 11-14].
Concurrently with this announcement, the company announced its intent to begin a process to sell its Alkali business.
(NYSE: TROX) has closed the sale its Alkali Chemicals business to US-based midstream energy master limited partnership Genesis Energy, L.P.
Instead, he was collecting data on the alkali bee, a solitary, ground-nesting species that alfalfa seed growers count on for peak yields.
The method of preparing the modified conjugated diene-based polymer includes (a) polymerizing a vinyl aromatic monomer and a conjugated diene monomer using an organo-alkali metal compound in the presence of a hydrocarbon solvent, thus forming an active polymer having an alkali metal end; and (b) coupling or linking the active polymer having the alkali metal end with a compound represented by chemical formula 1 or 2.