Alkali definition

ălkə-lī
A substance having highly basic properties; a strong base.
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A carbonate or hydroxide of an alkali metal, the aqueous solution of which is bitter, slippery, caustic, and characteristically basic in reactions.
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Any base or hydroxide, as soda, potash, etc. that is soluble in water and gives a high concentration of hydroxyl ions in solution; specif., any of the hydroxides and carbonates of the alkali metals.
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The definition of an alkali is a soluble salt that comes from the ashes of plants and is made up of mostly potassium or sodium carbonate.

Lye and calcium carbonate are each an example of an alkali.

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Soda ash; caustic soda, caustic potash, etc.
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Any of various soluble mineral salts found in natural water and arid soils.
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(Western United States) Soluble mineral matter, other than common salt, contained in soils of natural waters.
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(chemistry) One of a class of caustic bases, such as soda, potash, ammonia, and lithia, whose distinguishing peculiarities are solubility in alcohol and water, uniting with oils and fats to form soap, neutralizing and forming salts with acids, turning to brown several vegetable yellows, and changing reddened litmus to blue.
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Any soluble substance, as a mineral salt or mixture of salts, that can neutralize acids, has a pH greater than 7.0, and turns litmus blue: strong alkalies are caustic.
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A hydroxide of an alkali metal. The aqueous solution of alkalis is bitter, slippery, caustic, and characteristically basic in reactions.
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Alkali metal.
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Other Word Forms

Noun

Singular:
alkali
Plural:
alkalies, alkalis

Origin of alkali

  • Middle English alkaline substance from calcined plant ashes from Medieval Latin from Arabic al-qily the ashes, lye, potash al- the qily ashes (from qalā to fry, roast qly in Semitic roots)

    From American Heritage Dictionary of the English Language, 5th Edition

  • French alcali, ultimately from Arabic القلي (al-qilī, “ashes of the saltwort”), from قلى (qalā, “to roast in a pan, fry”).

    From Wiktionary