Potassium Carbonate
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Potassium carbonate is the
inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
with the formula K2 CO3. It is a white
salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...
, which is
soluble In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubil ...
in
water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...
. It is
deliquescent Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance' ...
, often appearing as a damp or wet
solid Solid is one of the State of matter#Four fundamental states, four fundamental states of matter (the others being liquid, gas, and Plasma (physics), plasma). The molecules in a solid are closely packed together and contain the least amount o ...
. Potassium carbonate is mainly used in the production of soap and
glass Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling (quenching) of ...
.


History

Potassium carbonate is the primary component of
potash Potash () includes various mined and manufactured salts that contain potassium in water-soluble form.
and the more refined pearl ash or salts of tartar. Historically, pearl ash was created by baking potash in a
kiln A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. Kilns have been used for millennia to turn objects made from clay int ...
to remove impurities. The fine, white powder remaining was the pearl ash. The first
patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A p ...
issued by the
US Patent Office The United States Patent and Trademark Office (USPTO) is an agency in the U.S. Department of Commerce that serves as the national patent office and trademark registration authority for the United States. The USPTO's headquarters are in Alexa ...
was awarded to Samuel Hopkins in 1790 for an improved method of making potash and pearl ash. In late 18th-century
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
, before the development of
baking powder Baking powder is a dry chemical leavening agent, a mixture of a carbonate or bicarbonate and a weak acid. The base and acid are prevented from reacting prematurely by the inclusion of a buffer such as cornstarch. Baking powder is used to increas ...
, pearl ash was used as a
leavening agent In cooking, a leavening agent () or raising agent, also called a leaven () or leavener, is any one of a number of substances used in doughs and batters that cause a foaming action (gas bubbles) that lightens and softens the mixture. An altern ...
for
quick bread Quick bread is any bread leavened with a chemical leavening agent rather than a biological one like yeast or sourdough starter. An advantage of quick breads is their ability to be prepared quickly and reliably, without requiring the time-consumi ...
s.


Production

Potassium carbonate is prepared commercially by the reaction
potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which exp ...
with
carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...
: : 2 KOH + CO2 → K2CO3 + H2O From the solution crystallizes the sesquihydrate K2CO3·H2O ("potash hydrate"). Heating this solid above gives the anhydrous salt. In an alternative method, potassium chloride is treated with carbon dioxide in the presence of an organic amine to give
potassium bicarbonate Potassium bicarbonate (IUPAC name: potassium hydrogencarbonate, also known as potassium acid carbonate) is the inorganic compound with the chemical formula KHCO3. It is a white solid. Production and reactivity It is manufactured by treating an ...
, which is then
calcined Calcination refers to thermal treatment of a solid chemical compound (e.g. mixed carbonate ores) whereby the compound is raised to high temperature without melting under restricted supply of ambient oxygen (i.e. gaseous O2 fraction of air), gener ...
: : 2 KHCO3 → K2CO3 + H2O + CO2


Applications

* (historically) for
soap Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are use ...
,
glass Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling (quenching) of ...
, and dishware production * as a mild drying agent where other drying agents, such as
calcium chloride Calcium chloride is an inorganic compound, a salt with the chemical formula . It is a white crystalline solid at room temperature, and it is highly soluble in water. It can be created by neutralising hydrochloric acid with calcium hydroxide. Ca ...
and
magnesium sulfate Magnesium sulfate or magnesium sulphate (in English-speaking countries other than the US) is a chemical compound, a salt with the formula , consisting of magnesium cations (20.19% by mass) and sulfate anions . It is a white crystalline solid, ...
, may be incompatible. It is not suitable for acidic compounds, but can be useful for drying an organic phase if one has a small amount of acidic impurity. It may also be used to dry some ketones,
alcohols In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl () functional group bound to a saturated carbon atom. The term ''alcohol'' originally referred to the primary alcohol ethanol (ethyl alcohol), which is ...
, and
amines In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent such ...
prior to distillation. * in
cuisine A cuisine is a style of cooking characterized by distinctive ingredients, techniques and dishes, and usually associated with a specific culture or geographic region. Regional food preparation techniques, customs, and ingredients combine to ...
, where it has many traditional uses. It is an ingredient in the production of
grass jelly Grass jelly, also known as leaf jelly or herb jelly, is a jelly-like dessert eaten in East and Southeast Asia. It is created by using Chinese mesona (a member of the mint family) and has a mild, slightly bitter taste. It is served chilled, w ...
, a food consumed in
Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of ...
and Southeast Asian cuisines, as well as Chinese hand-pulled noodles and
mooncakes A mooncake () is a Chinese bakery products, Chinese bakery product traditionally eaten during the Mid-Autumn Festival (中秋節). The festival is about lunar appreciation and Moon watching, and mooncakes are regarded as a delicacy. Mooncak ...
. It is also used to
tenderize Tenderness is a quality of meat gauging how easily it is chewed or cut. Tenderness is a desirable quality, as tender meat is softer, easier to chew, and generally more palatable than harder meat. Consequently, tender cuts of meat typically command h ...
tripe Tripe is a type of edible lining from the stomachs of various farm animals. Most tripe is from cattle, pigs and sheep. Types of tripe Beef tripe Beef tripe is made from the muscle wall (the interior mucosal lining is removed) of a cow's st ...
. German gingerbread recipes often use potassium carbonate as a baking agent, although in combination with
hartshorn Hartshorn is the antler of male red deer. Derivatives Various nitrogen compounds were made from hartshorn shavings: * Oil of hartshorn is a crude chemical product obtained from the destructive distillation of deer antlers. * Salt of hartshorn r ...
. Use of potassium carbonate must be limited to a certain amount to prevent harm, and should not be used without guidance. * in the alkalization of cocoa powder to produce
Dutch process chocolate Dutch processed cocoa, Dutch cocoa, or alkalized cocoa, is cocoa solids that have been treated with an alkalizing agent to reduce the natural acidity of cocoa, giving it a less bitter taste (and darker colour) compared to "natural cocoa" extract ...
by balancing the pH (i.e., reduce the acidity) of natural
cocoa beans The cocoa bean (technically cocoa seed) or simply cocoa (), also called the cacao bean (technically cacao seed) or cacao (), is the dried and fully fermented seed of ''Theobroma cacao'', from which cocoa solids (a mixture of nonfat substances ...
; it also enhances
aroma An odor (American English) or odour ( Commonwealth English; see spelling differences) is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and animals can perceive via their se ...
. The process of adding potassium carbonate to cocoa powder is usually called "Dutching" (and the products referred to as Dutch-processed cocoa powder), as the process was first developed in 1828 by Dutchman
Coenraad Johannes van Houten Coenraad Johannes van Houten (15 March 1801 – 27 May 1887) was a Dutch chemist and chocolate maker known for the treatment of cocoa mass with alkaline salts to remove the bitter taste and make cocoa solids more water-soluble; the resulting pro ...
. * as a
buffering agent A buffer solution (more precisely, pH buffer or hydrogen ion buffer) is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa. Its pH changes very little when a small amount of strong acid or base is ...
in the production of
mead Mead () is an alcoholic beverage made by fermenting honey mixed with water, and sometimes with added ingredients such as fruits, spices, grains, or hops. The alcoholic content ranges from about 3.5% ABV to more than 20%. The defining character ...
or
wine Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...
. * in antique documents, it is reported to have been used to soften
hard water Hard water is water that has high mineral content (in contrast with "soft water"). Hard water is formed when water percolates through deposits of limestone, chalk or gypsum, which are largely made up of calcium and magnesium carbonates, bicarbo ...
.Child, Lydia M. "The American Frugal Housewife" 1832 * as a fire suppressant in extinguishing deep-fat fryers and various other B class-related fires. * in
condensed aerosol fire suppression Condensed aerosol fire suppression is a particle-based form of fire extinction. It is similar to dry chemical fire extinction). It employs a fire-extinguishing agent consisting of: very fine solid particles as well as gaseous matter. The cond ...
, although as the byproduct of
potassium nitrate Potassium nitrate is a chemical compound with the chemical formula . This alkali metal nitrate salt is also known as Indian saltpetre (large deposits of which were historically mined in India). It is an ionic salt of potassium ions K+ and nitrat ...
. * as an ingredient in welding fluxes, and in the flux coating on arc-welding rods. * as an animal feed ingredient to satisfy the potassium requirements of farmed animals such as broiler breeder chickens. * as an acidity regulator in
Swedish Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used by ...
''
snus Snus ( , ) is a tobacco product, originating from a variant of dry snuff in early 18th-century Sweden. It is placed between the upper lip and gum for extended periods, as a form of sublabial administration. Snus is not fermented. Although used ...
'' snuff tobacco


References


Bibliography

* ''A Dictionary of Science'',
Oxford University Press Oxford University Press (OUP) is the university press of the University of Oxford. It is the largest university press in the world, and its printing history dates back to the 1480s. Having been officially granted the legal right to print books ...
, New York, 2004 *


External links


International Chemical Safety Card 1588
{{Authority control Carbonates Leavening agents Potassium compounds Deliquescent substances Desiccants Photographic chemicals Food stabilizers