SUPPORT THE WORK

GetWiki

alkali

ARTICLE SUBJECTS
aesthetics  →
being  →
complexity  →
database  →
enterprise  →
ethics  →
fiction  →
history  →
internet  →
knowledge  →
language  →
licensing  →
linux  →
logic  →
method  →
news  →
perception  →
philosophy  →
policy  →
purpose  →
religion  →
science  →
sociology  →
software  →
truth  →
unix  →
wiki  →
ARTICLE TYPES
essay  →
feed  →
help  →
system  →
wiki  →
ARTICLE ORIGINS
critical  →
discussion  →
forked  →
imported  →
original  →
alkali
[ temporary import ]
please note:
- the content below is remote from Wikipedia
- it has been imported raw for GetWiki
{{pp-semi-indef}}{{Other uses|Alkali (disambiguation)}}{{distinguish|Alkalinity}}{{redirect|Alkaline|the power cell|Alkaline battery|the Jamaican dancehall musician|Alkaline (musician)}}{{Refimprove|date=June 2008}}In chemistry, an alkali ({{IPAc-en|ˈ|æ|l|k|əl|aɪ}}; from Arabic: al-qaly "ashes of the saltwort") is a basic, ionic salt of an alkali metal or alkaline earth metal chemical element. An alkali also can 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 is commonly, and alkalescent less often, 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.

Etymology

The word "alkali" is derived from Arabic al qalīy (or alkali),BOOK, Chambers's encyclopaedia: a dictionary of universal knowledge, Volume 1, J.B. Lippincott & Co, 1888, 148, 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 bases

Alkalis 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 7.1 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 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. The second subset of bases is also called an "Arrhenius base".

Alkali salts

Alkali salts are soluble hydroxides of alkali metals and alkaline earth metals, of which common examples are:
  • Sodium hydroxide – often called "caustic soda"
  • Potassium hydroxide – commonly called "caustic potash"
  • Lye – generic term for either of the previous two or even for a mixture
  • Calcium hydroxide – saturated solution known as "limewater"
  • Magnesium hydroxide – 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 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.

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.Examples of alkali lakes:

See also

References

{{Reflist|30em}}{{Authority control}}

- content above as imported from Wikipedia
- "alkali" does not exist on GetWiki (yet)
- time: 10:34am EDT - Fri, Jul 19 2019
[ this remote article is provided by Wikipedia ]
LATEST EDITS [ see all ]
GETWIKI 09 JUL 2019
Eastern Philosophy
History of Philosophy
GETWIKI 09 MAY 2016
GETWIKI 18 OCT 2015
M.R.M. Parrott
Biographies
GETWIKI 20 AUG 2014
GETWIKI 19 AUG 2014
CONNECT