In chemistry, an alkali (/ˈælkəlaɪ/; from Arabic: القلوي, romanized: al-qaly, lit. 'ashes of the saltwort') is a basic, ionicsalt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The adjectivealkaline, and less often, alkalescent, is commonly used in English as a synonym for basic, especially for bases soluble in water. This broad use of the term is likely to have come about because alkalis were the first bases known to obey the Arrhenius definition of a base, and they are still among the most common bases.
The word "alkali" is derived from Arabic al qalīy (or alkali),[1] meaning the calcined ashes (see calcination), referring to the original source of alkaline substances. A water-extract of burned plant ashes, called potash and composed mostly of potassium carbonate, was mildly basic. After heating this substance with calcium hydroxide (slaked lime), a far more strongly basic substance known as caustic potash (potassium hydroxide) was produced. Caustic potash was traditionally used in conjunction with animal fats to produce soft soaps, one of the caustic processes that rendered soaps from fats in the process of saponification, one known since antiquity. Plant potash lent the name to the element potassium, which was first derived from caustic potash, and also gave potassium its chemical symbol K (from the German name Kalium), which ultimately derived from alkali.
Alkaline solutions are slippery or soapy to the touch, due to the saponification of the fatty substances on the surface of the skin.
Alkalis are normally water-soluble, although some like barium carbonate are only soluble when reacting with an acidic aqueous solution.
Difference between alkali and base
The terms "base" and "alkali" are often used interchangeably, particularly outside the context of chemistry and chemical engineering.
There are various, more specific definitions for the concept of an alkali. Alkalis are usually defined as a subset of the bases. One of two subsets is commonly chosen.
A basic salt of an alkali metal or alkaline earth metal[2] (this includes Mg(OH)2 (magnesium hydroxide) but excludes NH3 (ammonia)).
Any base that is soluble in water and forms hydroxide ions[3][4] or the solution of a base in water.[5] (This includes both Mg(OH)2 and NH3, which forms NH4OH.)
The second subset of bases is also called an "Arrhenius base".
Magnesium hydroxide (Mg(OH)2) – an atypical alkali since it has low solubility in water (although the dissolved portion is considered a strong base due to complete dissociation of its ions)
Soils with pH values that are higher than 7.3 are usually defined as being alkaline. These soils can occur naturally, due to the presence of alkali salts. Although many plants do prefer slightly basic soil (including vegetables like cabbage and fodder like buffalo grass), most plants prefer a mildly acidic soil (with pHs between 6.0 and 6.8), and alkaline soils can cause problems.[1]
Alkali lakes
In alkali lakes (also called soda lakes), evaporation concentrates the naturally occurring carbonate salts, giving rise to an alkalic and often saline lake.
^alkali – definition of alkali by the Free Online Dictionary, Thesaurus and Encyclopedia. Thefreedictionary.com. Retrieved on 2012-04-18.
^Chung, L.H.M. (1997) , pp. 363–365 in Integrated Chemistry Today. ISBN9789623722520
^Acids, Bases and Salts. KryssTal. Retrieved on 2012-04-18.
^Davis, Jim and Milligan, Mark (2011). Why is Bear Lake so blue? 2015-07-02 at the Wayback Machine Public Information Series 96. Utah Geological Survey, Department of Natural Resources
January 07, 2023
alkali, other, uses, disambiguation, confused, with, nity, redirects, here, other, uses, disambiguation, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material,. For other uses see Alkali disambiguation Not to be confused with Alkalinity Alkaline redirects here For other uses see Alkaline disambiguation This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Alkali news newspapers books scholar JSTOR June 2008 Learn how and when to remove this template message In chemistry an alkali ˈ ae l k e l aɪ from Arabic القلوي romanized al qaly lit ashes of the saltwort is a basic ionic salt of an alkali metal or an alkaline earth metal An alkali can also be defined as a base that dissolves in water A solution of a soluble base has a pH greater than 7 0 The adjective alkaline and less often alkalescent is commonly used in English as a synonym for basic especially for bases soluble in water This broad use of the term is likely to have come about because alkalis were the first bases known to obey the Arrhenius definition of a base and they are still among the most common bases Contents 1 Etymology 2 Common properties of alkalis and bases 3 Difference between alkali and base 4 Alkali salts 5 Alkaline soil 6 Alkali lakes 7 See also 8 ReferencesEtymologyThe word alkali is derived from Arabic al qaliy or alkali 1 meaning the calcined ashes see calcination referring to the original source of alkaline substances A water extract of burned plant ashes called potash and composed mostly of potassium carbonate was mildly basic After heating this substance with calcium hydroxide slaked lime a far more strongly basic substance known as caustic potash potassium hydroxide was produced Caustic potash was traditionally used in conjunction with animal fats to produce soft soaps one of the caustic processes that rendered soaps from fats in the process of saponification one known since antiquity Plant potash lent the name to the element potassium which was first derived from caustic potash and also gave potassium its chemical symbol K from the German name Kalium which ultimately derived from alkali Common properties of alkalis and basesAlkalis are all Arrhenius bases ones which form hydroxide ions OH when dissolved in water Common properties of alkaline aqueous solutions include Moderately concentrated solutions over 10 3 M have a pH of 10 or greater This means that they will turn phenolphthalein from colorless to pink Concentrated solutions are caustic causing chemical burns Alkaline solutions are slippery or soapy to the touch due to the saponification of the fatty substances on the surface of the skin Alkalis are normally water soluble although some like barium carbonate are only soluble when reacting with an acidic aqueous solution Difference between alkali and baseThe terms base and alkali are often used interchangeably particularly outside the context of chemistry and chemical engineering There are various more specific definitions for the concept of an alkali Alkalis are usually defined as a subset of the bases One of two subsets is commonly chosen A basic salt of an alkali metal or alkaline earth metal 2 this includes Mg OH 2 magnesium hydroxide but excludes NH3 ammonia Any base that is soluble in water and forms hydroxide ions 3 4 or the solution of a base in water 5 This includes both Mg OH 2 and NH3 which forms NH4OH The second subset of bases is also called an Arrhenius base Alkali saltsAlkali salts are soluble hydroxides of alkali metals and alkaline earth metals of which common examples are Sodium hydroxide NaOH often called caustic soda Potassium hydroxide KOH commonly called caustic potash Lye generic term for either of two previous salts or their mixture Calcium hydroxide Ca OH 2 saturated solution known as limewater Magnesium hydroxide Mg OH 2 an atypical alkali since it has low solubility in water although the dissolved portion is considered a strong base due to complete dissociation of its ions Alkaline soilMain article Alkali soil Soils with pH values that are higher than 7 3 are usually defined as being alkaline These soils can occur naturally due to the presence of alkali salts Although many plants do prefer slightly basic soil including vegetables like cabbage and fodder like buffalo grass most plants prefer a mildly acidic soil with pHs between 6 0 and 6 8 and alkaline soils can cause problems 1 Alkali lakesIn alkali lakes also called soda lakes evaporation concentrates the naturally occurring carbonate salts giving rise to an alkalic and often saline lake Examples of alkali lakes Alkali Lake Lake County Oregon Baldwin Lake San Bernardino County California Bear Lake 6 on the Utah Idaho border Lake Magadi in Kenya Lake Turkana in Kenya Mono Lake near Owens Valley in California Redberry Lake Saskatchewan Summer Lake Lake County Oregon Tramping Lake SaskatchewanSee also Wikiquote has quotations related to Alkali Alkali metals Alkaline earth metals Base chemistry References a b Chambers s encyclopaedia a dictionary of universal knowledge Volume 1 J B Lippincott amp Co 1888 p 148 Alkali Define Alkali at Dictionary com Dictionary reference com Retrieved on 2012 04 18 alkali definition of alkali by the Free Online Dictionary Thesaurus and Encyclopedia Thefreedictionary com Retrieved on 2012 04 18 Chung L H M 1997 Characteristics of Alkali pp 363 365 in Integrated Chemistry Today ISBN 9789623722520 Acids Bases and Salts KryssTal Retrieved on 2012 04 18 Davis Jim and Milligan Mark 2011 Why is Bear Lake so blue Archived 2015 07 02 at the Wayback Machine Public Information Series 96 Utah Geological Survey Department of Natural Resources Retrieved from https en wikipedia org w index php title Alkali amp oldid 1123589143, wikipedia, wiki, book, books, library,
