Potassium carbonate is the
inorganic compound
An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bondsthat is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''.
Inorgan ...
with the formula . It is a white
salt
In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...
, 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 solubi ...
in
water
Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...
and forms a strongly alkaline solution. It is
deliquescent
Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption (chemistry), absorption or adsorption from the surrounding Natural environment, environment, which is usually at normal or room temperature. If water mol ...
, often appearing as a damp or wet
solid
Solid is a state of matter where molecules are closely packed and can not slide past each other. Solids resist compression, expansion, or external forces that would alter its shape, with the degree to which they are resisted dependent upon the ...
. Potassium carbonate is mainly used in the
production of soap and
glass
Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window pane ...
.
Commonly, it can be found as the result of
leakage of
alkaline batteries. Potassium carbonate is a
potassium
Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...
salt
In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...
of
carbonic acid
Carbonic acid is a chemical compound with the chemical formula . The molecule rapidly converts to water and carbon dioxide in the presence of water. However, in the absence of water, it is quite stable at room temperature. The interconversion ...
. This salt consists of potassium
cations
An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...
and
carbonate
A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group ...
anions
An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...
, and is therefore an
alkali metal
The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K),The symbols Na and K for sodium and potassium are derived from their Latin names, ''natrium'' and ''kalium''; these are still the origins of the names ...
carbonate.
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 salt 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, chemical changes. Kilns have been used for millennia to turn objects m ...
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 sufficiency of disclosure, enabling discl ...
issued by the
US Patent Office 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, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
, 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 Baker's yeast, yeast or Sourdough#Starter, sourdough starter. An advantage of quick breads is their ability to be prepared quickly and reliably, w ...
s.
Production
The modern commercial production of potassium carbonate is by reaction of
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 utili ...
with
carbon dioxide
Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
:
:
From the solution crystallizes the
sesquihydrate ("potash hydrate"). Heating this solid above gives the
anhydrous
A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achie ...
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:
:
Applications
* (historically) for
soap
Soap is a salt (chemistry), salt of a fatty acid (sometimes other carboxylic acids) used for cleaning and lubricating products as well as other applications. In a domestic setting, soaps, specifically "toilet soaps", are surfactants usually u ...
,
glass
Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window pane ...
, and
dishware
Tableware items are the dishware and utensils used for setting a table, serving food, and dining. The term includes cutlery, List of glassware, glassware, serving dishes, serving utensils, and other items used for practical as well as decorat ...
production;
* as a dietary potassium supplement, containing 56% of elemental potassium, in tablet or powder form to address low blood potassium levels caused by inadequate nourishment, nausea and vomiting, diarrhea, or potassium-depleting medications such as
corticosteroid
Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are invo ...
s or
diuretic
A diuretic () is any substance that promotes diuresis, the increased production of urine. This includes forced diuresis. A diuretic tablet is sometimes colloquially called a water tablet. There are several categories of diuretics. All diuretics ...
s;
* as a mild
drying agent where other drying agents, such as
calcium chloride
Calcium chloride is an inorganic compound, a Salt (chemistry), 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 cal ...
and
magnesium sulfate
Magnesium sulfate or magnesium sulphate 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, soluble in water but not in ethanol.
Magnesi ...
, 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
ketone
In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone ( ...
s;
alcohols
In chemistry, an alcohol (), is a type of organic compound that carries at least one hydroxyl () functional group bound to a Saturated and unsaturated compounds, saturated carbon atom. Alcohols range from the simple, like methanol and ethanol ...
, and
amine
In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of elec ...
s prior to distillation.
* in
cuisine
A cuisine is a style of cooking characterized by distinctive ingredients, List of cooking techniques, techniques and Dish (food), dishes, and usually associated with a specific culture or geographic region. Regional food preparation techniques, ...
, where it has many traditional uses. It is used in some types of
Chinese noodles
Chinese noodles vary widely according to the region of production, ingredients, shape or width, and manner of preparation. Noodles were invented in China, and are an essential ingredient and Staple food, staple in Chinese cuisine. They are an im ...
and
mooncake
A mooncake () is a Chinese bakery product traditionally eaten during the Mid-Autumn Festival (中秋節). The festival is primarily about the harvest while a legend connects it to moon watching, and mooncakes are regarded as a delicacy. ...
s, as well as Asian
grass jelly
Grass jelly, also known as leaf jelly or herbal jelly, is a Gelatin, jelly-like dessert originating in China. It is commonly consumed in East Asia and Southeast Asia. It is created by using Platostoma palustre, Chinese mesona (a member of the ...
and Japanese
ramen
is a Chinese noodle dish popularized in Japan. It includes served in several flavors of broth. Common flavors are soy sauce and miso, with typical toppings including , nori (dried seaweed), menma (bamboo shoots), and scallions. Ramen h ...
. German
gingerbread
Gingerbread refers to a broad category of baked goods, typically flavored with ginger root, ginger, cloves, nutmeg, and cinnamon and sweetened with honey, sugar, or molasses. Gingerbread foods vary, ranging from a moist loaf cake to forms nearly ...
recipes often use potassium carbonate as a baking agent, although in combination with
hartshorn;
* in the
alkalization of
cocoa powder to produce
Dutch process chocolate by balancing the
pH (i.e., reduce the acidity) of natural
cocoa bean
The cocoa bean, also known as cocoa () or cacao (), is the dried and fully fermented seed of ''Theobroma cacao'', the cacao tree, from which cocoa solids (a mixture of nonfat substances) and cocoa butter (the fat) can be extracted. Cacao tree ...
s; it also enhances
aroma
An odor (American English) or odour (Commonwealth English; see spelling differences) is a smell or a scent caused by one or more volatilized chemical compounds generally found in low concentrations that humans and many animals can perceive v ...
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;
* as a
buffering agent
A buffer solution is a solution where the pH does not change significantly on dilution or if an acid or base is added at constant temperature. Its pH changes very little when a small amount of strong acid or base is added to it. Buffer solution ...
in the production of
mead
Mead (), also called honey wine, and hydromel (particularly when low in alcohol content), is an alcoholic beverage made by fermenting honey mixed with water, and sometimes with added ingredients such as fruits, spices, grains, or hops. The alco ...
or
wine
Wine is an alcoholic drink made from Fermentation in winemaking, fermented fruit. Yeast in winemaking, Yeast consumes the sugar in the fruit and converts it to ethanol and carbon dioxide, releasing heat in the process. Wine is most often made f ...
;
* in antique documents, it is reported to have been used to
soften hard water
Hard water is water that has a 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, bic ...
;
* as a fire suppressant in
extinguishing deep-fat fryers and various other
oil/fat/grease related fires;
* in
condensed aerosol fire suppression, although as the byproduct of
potassium nitrate
Potassium nitrate is a chemical compound with a sharp, salty, bitter taste and the chemical formula . It is a potassium salt of nitric acid. This salt consists of potassium cations and nitrate anions , and is therefore an alkali metal nit ...
;
* as an ingredient in
welding fluxes, and in the flux coating on
arc-welding rods;
* as an
animal feed
Animal feed is food given to domestic animals, especially livestock, in the course of animal husbandry. There are two basic types: fodder and forage. Used alone, the word ''feed'' more often refers to fodder. Animal feed is an important input ...
ingredient to satisfy the
potassium requirements of
farmed animals such as
broiler breeder chickens;
* as an acidity regulator in
Swedish ''
snus
Snus (, ; ) is a Swedish smokeless tobacco, tobacco product. It is consumed by placing a pouch of powdered tobacco leaves under the lip for nicotine to be absorbed through the Mucous membrane, oral mucosa. Snus, not to be confused with Nicoti ...
''
snuff tobacco.
References
Bibliography
* ''A Dictionary of Science'',
Oxford University Press
Oxford University Press (OUP) is the publishing house of the University of Oxford. It is the largest university press in the world. Its first book was printed in Oxford in 1478, with the Press 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 materials
Desiccants
Photographic chemicals
Food stabilizers