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Sodium carbonate, ·10, (also known as Natrium Carbonate, washing soda, soda ash and soda crystals) is the
inorganic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during a ...
with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield moderately alkaline solutions in water. Historically, it was extracted from the ashes of plants growing in sodium-rich soils. Because the ashes of these sodium-rich plants were noticeably different from ashes of wood (once used to produce
potash Potash () includes various mined and manufactured salts In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structu ...
), sodium carbonate became known as "soda ash". It is produced in large quantities from
sodium chloride Sodium chloride , commonly known as salt (although sea salt also contains other chemical salt (chemistry), salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With Molar mass, molar ...
and
limestone Limestone is a common type of carbonate In chemistry, a carbonate is a salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistry), salts; salt in its na ...

limestone
by the
Solvay process The Solvay process or ammonia-soda process is the major industrial process for the production of (soda ash, Na2CO3). The ammonia-soda process was developed into its modern form by the Belgian chemist during the 1860s. The ingredients for this are ...

Solvay process
.


Hydrates

Sodium carbonate is obtained as three
hydrate In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds composed of atoms, m ...
s and as the anhydrous salt: * sodium carbonate decahydrate (
natron Natron is a naturally occurring mixture of sodium carbonate decahydrate (sodium carbonate, Na2CO3·10H2O, a kind of soda ash) and around 17% sodium bicarbonate (also called baking soda, NaHCO3) along with small quantities of sodium chloride and ...
), Na2CO3·10H2O, which readily effloresces to form the monohydrate. * sodium carbonate heptahydrate (not known in mineral form), Na2CO3·7H2O. * sodium carbonate monohydrate (
thermonatrite Thermonatrite is a naturally occurring evaporite evaporated from the Dead Sea, Israel Evaporite () is the term for a water-soluble mineral sediment Sediment is a naturally occurring material that is broken down by processes of weathering a ...
), Na2CO3·H2O. Also known as crystal carbonate. * anhydrous sodium carbonate, also known as calcined soda, is formed by heating the hydrates. It is also formed when sodium hydrogencarbonate is heated (calcined) e.g. in the final step of the
Solvay process The Solvay process or ammonia-soda process is the major industrial process for the production of (soda ash, Na2CO3). The ammonia-soda process was developed into its modern form by the Belgian chemist during the 1860s. The ingredients for this are ...

Solvay process
. The decahydrate is formed from water solutions crystallizing in the temperature range −2.1 to +32.0 °C, the heptahydrate in the narrow range 32.0 to 35.4 °C and above this temperature the monohydrate forms. In dry air the decahydrate and heptahydrate lose water to give the monohydrate. Other hydrates have been reported, e.g. with 2.5 units of water per sodium carbonate unit ("pentahemihydrate").


Washing soda

Sodium carbonate decahydrate (Na2CO3·10H2O), also known as washing soda, is the most common hydrate of sodium carbonate containing 10 molecules of
water of crystallizationIn chemistry, water(s) of crystallization or water(s) of hydration are water Water (chemical formula H2O) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's ...
. Soda ash is dissolved in water and crystallized to get washing soda. Na2CO3 + 10H2O -> Na2CO3.10H2O * It is white
crystalline A crystal or crystalline solid is a solid Solid is one of the four fundamental states of matter (the others being liquid, gas and plasma). The molecules in a solid are closely packed together and contain the least amount of kinet ...

crystalline
solid; * It is one of the few metal
carbonates In chemistry, a carbonate is a salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistry), salts; salt in its natural form as a crystallinity, crystalline min ...

carbonates
which are soluble in water; * It is alkaline; it turns red
litmus Litmus is a water soluble, water-soluble mixture of different dyes extracted from lichens. It is often absorbed onto filter paper to produce one of the oldest forms of pH indicator, used to test materials for acidity. History The word "litm ...
to blue; * It has
detergent A detergent is a surfactant Surfactants are compounds that lower the surface tension (or interfacial tension) between two liquids, between a gas and a liquid, or between a liquid and a solid. Surfactants may act as detergents, wetting ...
properties through the process of
saponification Saponification is a process that involves the conversion of fat, oil, or lipid, into soap and alcohol by the action of aqueous alkali (e.g. Sodium hydroxide, NaOH). Soaps are salts of fatty acids, which in turn are carboxylic acids with long carbon ...

saponification
which makes fats and grease water-miscible.


Applications

Some common applications of sodium carbonate (or washing soda) include: * Sodium carbonate (or washing soda) is used as a cleansing agent for domestic purposes like washing clothes. Sodium carbonate is a component of many dry soap powders. * It is used for removing temporary and permanent hardness of water. ''(see
water softening Water softening is the removal of calcium Calcium is a chemical element with the Symbol (chemistry), symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to ...
).'' * It is used in the manufacture of
glass Glass is a non- crystalline, often transparency and translucency, 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 ...

glass
,
soap Soap is a salt (chemistry), 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, ...

soap
and
paper Paper is a thin sheet material Material is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance, a material with a definite chemical composition ...

paper
. ''(see )'' * It is used in the manufacture of sodium compounds like
borax Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron chemical substance, compound, a mineral, and a salt (chemistry), salt of boric acid. Powdered borax is white, consisting of soft colorless c ...

borax
.


Glass manufacture

Sodium carbonate serves as a
flux of \mathbf(\mathbf) with the unit normal vector \mathbf(\mathbf) ''(blue arrows)'' at the point \mathbf multiplied by the area dS. The sum of \mathbf\cdot\mathbf dS for each patch on the surface is the flux through the surface Flux describes ...
for
silica Silicon dioxide, also known as silica, is an oxide An oxide () is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any su ...

silica
, lowering the melting point of the mixture to something achievable without special materials. This "soda glass" is mildly water-soluble, so some
calcium carbonate Calcium carbonate is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together ...

calcium carbonate
is added to the melt mixture to make the glass insoluble. Bottle and window glass (
soda-lime glass Soda lime is a mixture of NaOH & CaO chemical A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent el ...
) is made by melting such mixtures of sodium carbonate, calcium carbonate, and silica sand (
silicon dioxide Silicon dioxide, also known as silica, is an oxide of rutile. Ti(IV) centers are grey; oxygen centers are red. Notice that oxygen forms three bonds to titanium and titanium forms six bonds to oxygen. An oxide () is a chemical compound that con ...
(SiO2)). When these materials are heated, the carbonates release carbon dioxide. In this way, sodium carbonate is a source of sodium oxide. Soda-lime glass has been the most common form of glass for centuries.


Water softening

Hard water contains dissolved compounds, usually calcium or magnesium compounds. Sodium carbonate is used for removing temporary and permanent hardness of water.https://www.ccmr.cornell.edu/wp-content/uploads/sites/2/2015/11/Water-Hardness-Reading.pdf As sodium carbonate is water-soluble and
magnesium carbonate Magnesium carbonate, Mg CO3 (archaic name magnesia alba), is an inorganic salt that is a white solid. Several hydrate In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, com ...

magnesium carbonate
and
calcium carbonate Calcium carbonate is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together ...

calcium carbonate
are insoluble, the former is used to soften water by removing Mg2+ and Ca2+. These ions form insoluble solid precipitates upon treatment with
carbonate In chemistry, a carbonate is a salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistry), salts; salt in its natural form as a crystallinity, crystalline mi ...

carbonate
ions: :Ca^2+ + CO3^2- -> CaCO3 Ca^2+(aq) + Na2CO3(aq) -> CaCO3(s) + 2Na+(aq) Similarly, Mg^2+(aq) + Na2CO3(aq) -> MgCO3(s) + 2Na+(aq) The water is softened because it no longer contains dissolved calcium ions and magnesium ions.


Food additive and cooking

Sodium carbonate has several uses in cuisine, largely because it is a stronger base than baking soda (
sodium bicarbonate Sodium bicarbonate ( IUPAC name: sodium hydrogen carbonate), commonly known as baking soda or bicarbonate of soda, is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cation (Na+) and a bicarbonate anion ( HCO3 ...

sodium bicarbonate
) but weaker than
lye A lye is a metal hydroxideMetal hydroxides are hydroxides of metals. They are often strong base (chemistry), bases. They consist of hydroxide anions and metallic cations. Some metal hydroxides, such as alkali metal hydroxides, ionize completel ...
(which may refer to
sodium hydroxide Sodium hydroxide, also known as lye A lye is a metal hydroxide traditionally obtained by leaching wood ashes, or a strong alkali In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chem ...

sodium hydroxide
or, less commonly,
potassium hydroxide Potassium hydroxide is an inorganic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, ...

potassium hydroxide
). Alkalinity affects
gluten Gluten is a protein naturally found in some grains including wheat, barley, and rye. Although, strictly speaking, "gluten" pertains only to wheat proteins, in the medical literature it refers to the combination of prolamin and glutelin proteins ...

gluten
production in kneaded doughs, and also improves browning by reducing the temperature at which the
Maillard reaction The Maillard reaction ( ; ) is a chemical reaction between Amino acid, amino acids and Reducing sugar, reducing sugars that gives browned food its distinctive flavor. Searing, Seared steaks, fried dumplings, cookies and other kinds of biscuits, b ...
occurs. To take advantage of the former effect, sodium carbonate is therefore one of the components of , a solution of alkaline salts used to give
Japanese Japanese may refer to: * Something from or related to Japan , image_flag = Flag of Japan.svg , alt_flag = Centered deep red circle on a white rectangle , image_coat = Imperial Seal of J ...
ramen is a Japanese Japanese may refer to: * Something from or related to Japan , image_flag = Flag of Japan.svg , alt_flag = Centered deep red circle on a white rectangle , image_coat ...

ramen
noodles their characteristic flavor and chewy texture; a similar solution is used in
Chinese cuisine Chinese cuisine is an important part of and includes s originating from . Because of the and historical power of the country, Chinese cuisine has influenced many other cuisines in and beyond, with modifications made to cater to local palat ...

Chinese cuisine
to make
lamian Lamian (simplified Chinese Simplified Chinese characters are standardized Chinese characters Chinese characters, also called ''hanzi'' (), are logogram In a written language A written language is the representation of ...
, for similar reasons.
Cantonese Cantonese ( zh, t=廣東話, s=广东话, first=t; Yale Yale University is a private Ivy League The Ivy League (also known as The Ancient Eight) is an American collegiate athletic conference comprising eight private research un ...
bakers similarly use sodium carbonate as a substitute for lye-water to give s their characteristic texture and improve browning. In
German cuisine The cuisine of Germany () is made up of many different local or regional cuisines, reflecting the country's federal history. Germany itself is part of a larger cultural region, Central Europe, sharing many traditions with neighbouring countrie ...
(and Central European cuisine more broadly), breads such as
pretzel A pretzel (), from dialectal German pronunciation, standard german: Breze(l) ( and French language, French / Alsatian dialect, Alsatian: ''Bretzel'') is a type of baking, baked pastry made from dough that is commonly shaped into a knot. The tradi ...

pretzel
s and
lye roll Lye rolls are a baked specialty in Germany ) , image_map = , map_caption = , map_width = 250px , capital = Berlin , coordinates = , largest_city = capital , languages_type = Official language , languages = German language, Germa ...
s traditionally treated with lye to improve browning can be treated instead with sodium carbonate; sodium carbonate does not produce quite as strong a browning as lye, but is much safer and easier to work with. Sodium carbonate is used in the production of sherbet powder. The cooling and fizzing sensation results from the endothermic reaction between sodium carbonate and a weak acid, commonly
citric acid Citric acid is an organic compound In , organic compounds are generally any s that contain - . Due to carbon's ability to (form chains with other carbon s), millions of organic compounds are known. The study of the properties, reactions, ...

citric acid
, releasing carbon dioxide gas, which occurs when the sherbet is moistened by saliva. Sodium carbonate also finds use in
food industry The food industry is a complex, global network of diverse businesses that supplies most of the food consumed by the World population, world's population. The term food industries covers a series of industrial activities directed at the producti ...
as a
food additive Food is any substance consumed to provide nutritional support for an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology ...
(E500) as an acidity regulator, anticaking agent, raising agent, and stabilizer. It is also used in the production of ''
snus Snus ( , ) is a tobacco Tobacco is the common name of several plants in the ' of the , and the general term for any product prepared from the of these plants. of tobacco are known, but the chief commercial crop is . The more potent ...

snus
'' to stabilize the pH of the final product. While it is less likely to cause chemical burns than lye, care must still be taken when working with sodium carbonate in the kitchen, as it is corrosive to aluminum cookware, utensils, and foil.


Inexpensive, weak base

Sodium carbonate is also used as a relatively strong
base Base or BASE may refer to: Brands and enterprises * Base (mobile telephony provider), a Belgian mobile telecommunications operator *Base CRM Base CRM (originally Future Simple or PipeJump) is an enterprise software company based in Mountain Vie ...
in various fields. As a common alkali, it is preferred in many chemical processes because it is cheaper than
sodium hydroxide Sodium hydroxide, also known as lye A lye is a metal hydroxide traditionally obtained by leaching wood ashes, or a strong alkali In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chem ...

sodium hydroxide
and far safer to handle. Its mildness especially recommends its use in domestic applications. For example, it is used as a regulator to maintain stable alkaline conditions necessary for the action of the majority of photographic
film developing Photographic processing or photographic development is the chemical means by which photographic film Photographic film is a strip or sheet of transparent film base coated on one side with a gelatin photographic emulsion, emulsion containing micr ...
agents. It is also a common additive in
swimming pool A swimming pool, swimming bath, wading pool, paddling pool, or simply pool, is a structure designed to hold water to enable Human swimming, swimming or other leisure activities. Pools can be built into the ground (in-ground pools) or built ...

swimming pool
s and
aquarium An aquarium (plural: ''aquariums'' or ''aquaria'') is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. fishkeeping, Fishkeepers use aquaria to keep fish, invertebrates, amp ...

aquarium
water to maintain a desired pH and carbonate hardness (KH). In
dyeing Dyeing is the application of dyes 300px, Yarn drying after being dyed in the early American tradition, at living_history_museum.html"_;"title="Conner_Prairie_living_history_museum">Conner_Prairie_living_history_museum. A_dye_is_a_ Conner_Pr ...

dyeing
with fiber-reactive dyes, sodium carbonate (often under a name such as soda ash fixative or soda ash activator) is used to ensure proper chemical bonding of the dye with cellulose (plant) fibers, typically before dyeing (for tie dyes), mixed with the dye (for dye painting), or after dyeing (for immersion dyeing). It is also used in the froth flotation process to maintain a favourable as a float conditioner besides
CaO Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter ...
and other mildly basic compounds.


Precursor to other compounds

Sodium (NaHCO3) or baking soda, also a component in fire extinguishers, is often generated from sodium carbonate. Although NaHCO3 is itself an intermediate product of the Solvay process, the heating needed to remove the ammonia that contaminates it decomposes some NaHCO3, making it more economic to react finished Na2CO3 with CO2: :Na2CO3 + CO2 + H2O → 2NaHCO3 In a related reaction, sodium carbonate is used to make
sodium bisulfite Sodium bisulfite (or sodium bisulphite, sodium hydrogen sulfite) is a chemical mixture with the approximate chemical formula NaHSO3. Sodium bisulfite in fact is not a real compound, but a mixture of salts that dissolve in water to give solutions c ...

sodium bisulfite
(NaHSO3), which is used for the "sulfite" method of separating
lignin Lignin is a class of complex organic polymer A polymer (; Greek ''poly- Poly, from the Greek :wikt:πολύς, πολύς meaning "many" or "much", may refer to: Businesses * China Poly Group Corporation, a Chinese business group, and its s ...

lignin
from cellulose. This reaction is exploited for removing
sulfur dioxide Sulfur dioxide (IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering OrganizationsNational Adhering Organizations in chemistry are the organizations that work as the autho ...
from flue gases in power stations: :Na2CO3 + SO2 + H2O → NaHCO3 + NaHSO3 This application has become more common, especially where stations have to meet stringent emission controls. Sodium carbonate is used by the cotton industry to neutralize the sulfuric acid needed for acid delinting of fuzzy cottonseed.


Miscellaneous

Sodium carbonate is used by the brick industry as a wetting agent to reduce the amount of water needed to extrude the clay. In casting, it is referred to as "bonding agent" and is used to allow wet
alginate Alginic acid, also called algin, is a polysaccharide distributed widely in the cell walls of brown algae that is hydrophilic and forms a viscous natural gum, gum when hydrated. With metals such as sodium and calcium, its salts are known as alginat ...
to adhere to gelled alginate. Sodium carbonate is used in toothpastes, where it acts as a foaming agent and an abrasive, and to temporarily increase mouth pH. Sodium carbonate is also used in the processing and tanning of animal hides.


Physical properties

The integral
enthalpy of solutionThe enthalpy of solution, enthalpy of dissolution, or heat of solution is the enthalpy change associated with the dissolution of a substance in a solvent at constant pressure resulting in infinite dilution. The enthalpy of solution is most often exp ...
of sodium carbonate is −28.1 kJ/mol for a 10% w/w aqueous solution. The
Mohs hardness The Mohs scale of mineral hardness () is a Qualitative property, qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was creat ...
of sodium carbonate monohydrate is 1.3.


Occurrence as natural mineral

Sodium carbonate is soluble in water, and can occur naturally in arid regions, especially in mineral deposits (''evaporites'') formed when seasonal lakes evaporate. Deposits of the mineral
natron Natron is a naturally occurring mixture of sodium carbonate decahydrate (sodium carbonate, Na2CO3·10H2O, a kind of soda ash) and around 17% sodium bicarbonate (also called baking soda, NaHCO3) along with small quantities of sodium chloride and ...
have been mined from dry lake bottoms in Egypt since ancient times, when natron was used in the preparation of
mummies A mummy is a dead human Humans (''Homo sapiens'') are the most populous and widespread species of primates, characterized by bipedality, opposable thumbs, hairlessness, and intelligence allowing the use of culture, language and tools. Th ...

mummies
and in the early manufacture of glass. The anhydrous mineral form of sodium carbonate is quite rare and called natrite. Sodium carbonate also erupts from
Ol Doinyo Lengai Ol Doinyo Lengai (Oldoinyo Lengai), "Mountain of God" in the Maasai language, is an active volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and Volcanic gas, gases ...

Ol Doinyo Lengai
, Tanzania's unique volcano, and it is presumed to have erupted from other volcanoes in the past, but due to these minerals' instability at the earth's surface, are likely to be eroded. All three mineralogical forms of sodium carbonate, as well as
trona Trona (trisodium hydrogendicarbonate dihydrate In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to th ...
, trisodium hydrogendicarbonate dihydrate, are also known from ultra-alkaline pegmatitic rocks, that occur for example in the
Kola Peninsula The Kola Peninsula (russian: Ко́льский полуо́стров, ') is a peninsula A peninsula ( la, paeninsula from ' "almost" and ' "island") is a landform surrounded by water on most of its border while being connected to a main ...
in Russia. Extraterrestrially, known sodium carbonate is rare. Deposits have been identified as the source of
bright spots on Ceres Several bright surface features (also known as faculae) were discovered on the dwarf planet Ceres by the ''Dawn'' spacecraft in 2015. The brightest cluster of spots ("Spot 5") is located in an crater called Occator (crater), Occator. The lar ...
, interior material that has been brought to the surface. While there are carbonates on Mars, and these are expected to include sodium carbonate, deposits have yet to be confirmed, this absence is explained by some as being due to a global dominance of low in previously aqueous
Martian soil Martian soil is the fine regolith Regolith () is a blanket of unconsolidated, loose, Homogeneity and heterogeneity, heterogeneous superficial deposits covering solid Rock (geology), rock. It includes dust, broken rocks, and other related materia ...
.


Production


Mining

Trona Trona (trisodium hydrogendicarbonate dihydrate In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to th ...
, (Na3HCO3CO3·2H2O), is mined in several areas of the US and provides nearly all the domestic consumption of sodium carbonate. Large natural deposits found in 1938, such as the one near
Green River, Wyoming Green River is a city in and the county seat of Sweetwater County, Wyoming, Sweetwater County, Wyoming, United States, in the southwestern part of the state. The population was 12,515 at the United States Census, 2010, 2010 census. History The ...
, have made mining more economical than industrial production in North America. There are important reserves of trona in Turkey; two million tons of soda ash have been extracted from the reserves near Ankara. It is also mined from some alkaline lakes such as
Lake Magadi Lake Magadi is the southernmost lake in the Kenyan Rift Valley, lying in a catchment of faulted volcanic rocks, north of Tanzania's Lake Natron. During the dry season, it is 80% covered by Sodium carbonate, soda and is well known for its wading bir ...

Lake Magadi
in Kenya by dredging. Hot saline springs continuously replenish salt in the lake so that, provided the rate of dredging is no greater than the replenishment rate, the source is fully sustainable.


Barilla and kelp

Several "
halophyte A halophyte is a salt-tolerant plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular r ...
" (salt-tolerant) plant species and seaweed species can be processed to yield an impure form of sodium carbonate, and these sources predominated in Europe and elsewhere until the early 19th century. The land plants (typically
glasswort The glassworts are various succulent, annual halophytes, halophytic plants, that is, plants that thrive in saline water, saline environments, such as seacoasts and salt marshes. The original English glasswort plants belong to the genus ''Salicornia ...

glasswort
s or
saltwortSaltwort is a common name for various genera of flowering plants that thrive in salty environments, typically in coastal salt marshes and seashores. Including various matter such as: :*'' Salsola'' and related genera within subfamily '' Salsoloidea ...
s) or the seaweed (typically ''
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'' species) were harvested, dried, and burned. The ashes were then " lixivated" (washed with water) to form an alkali solution. This solution was boiled dry to create the final product, which was termed "soda ash"; this very old name refers derives from the Arabic word ''soda'', in turn applied to
salsola soda ''Salsola soda'', more commonly known in English as opposite-leaved Salsola, saltwort, oppositeleaf Russian thistle, or barilla plant, is a small (to 0.7 m tall), annual, succulent shrub that is native to the Mediterranean Basin. It is a halophyt ...

salsola soda
, one of the many species of seashore plants harvested for production. "Barilla" is a commercial term applied to an impure form of
potash Potash () includes various mined and manufactured salts In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structu ...
obtained from coastal plants or
kelp Kelps are large brown algae The brown algae (singular: alga), comprising the class (biology), class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Most b ...

kelp
. The sodium carbonate concentration in soda ash varied very widely, from 2–3 percent for the seaweed-derived form ("
kelp Kelps are large brown algae The brown algae (singular: alga), comprising the class (biology), class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Most b ...

kelp
"), to 30 percent for the best
barilla ''Barilla'' refers to several species of salt-tolerant ( halophyte) plants that, until the 19th Century, were the primary source of soda ash and hence of sodium carbonate Sodium carbonate, , (also known as washing soda, soda ash and soda crys ...
produced from
saltwortSaltwort is a common name for various genera of flowering plants that thrive in salty environments, typically in coastal salt marshes and seashores. Including various matter such as: :*'' Salsola'' and related genera within subfamily '' Salsoloidea ...
plants in Spain. Plant and seaweed sources for soda ash, and also for the related
alkali In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds composed of ato ...

alkali
"
potash Potash () includes various mined and manufactured salts In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structu ...
", became increasingly inadequate by the end of the 18th century, and the search for commercially viable routes to synthesizing soda ash from salt and other chemicals intensified. Clow, Archibald and Clow, Nan L. (1952). ''Chemical Revolution,'' (Ayer Co Pub, June 1952), pp. 65–90. .


Leblanc process

In 1792, the French chemist
Nicolas Leblanc Nicolas Leblanc (6 December 1742 – 16 January 1806) was a French chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist A scientist is a person who conducts Scienti ...
patented a process for producing sodium carbonate from salt,
sulfuric acid Sulfuric acid (American spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography English orthogra ...

sulfuric acid
,
limestone Limestone is a common type of carbonate In chemistry, a carbonate is a salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistry), salts; salt in its na ...

limestone
, and coal. In the first step, sodium chloride is treated with sulfuric acid in the Mannheim process. This reaction produces
sodium sulfate Sodium sulfate (also known as sodium sulphate or sulfate of soda) 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 compou ...

sodium sulfate
(''salt cake'') and
hydrogen chloride The compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fortified with d ...

hydrogen chloride
: : 2NaCl + H2SO4 → Na2SO4 + 2HCl The salt cake and crushed
limestone Limestone is a common type of carbonate In chemistry, a carbonate is a salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistry), salts; salt in its na ...

limestone
(
calcium carbonate Calcium carbonate is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together ...

calcium carbonate
) was reduced by heating with
coal Coal is a combustible , Germany ) , image_map = , map_caption = , map_width = 250px , capital = Berlin , coordinates = , largest_city = capital , languages_type = Official language , languages = German language, German , ...

coal
. This conversion entails two parts. First is the
carbothermic reactionCarbothermic reactions involve the reduction of substances, often metal oxides (O^2-), using carbon Carbon (from la, carbo "coal") is a chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic tab ...
whereby the coal, a source of
carbon Carbon (from la, carbo "coal") is a with the C and 6. It is lic and —making four s available to form s. It belongs to group 14 of the periodic table. Carbon makes up only about 0.025 percent of Earth's crust. Three occur naturally, ...

carbon
, the
sulfate The sulfate or sulphate ion is a polyatomic anion An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having ...

sulfate
to
sulfide Sulfide (British English British English (BrE) is the standard dialect of the English language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon England, early medieval England, whi ...

sulfide
: : Na2SO4 + 2C → Na2S + 2CO2 The second stage is the reaction to produce sodium carbonate and
calcium sulfide Calcium sulfide is the chemical compound with the formula Calcium, CaSulfide, S. This white material crystallizes in cubes like rock salt. CaS has been studied as a component in a process that would recycle gypsum, a product of flue-gas desulfur ...
: : Na2S + CaCO3 → Na2CO3 + CaS This mixture is called ''black ash''. The soda ash is extracted from the black ash with water. Evaporation of this extract yields solid sodium carbonate. This extraction process was termed lixiviating. The hydrochloric acid produced by the
Leblanc process The Leblanc process was an early industrial process Industrial processes are procedures involving chemical A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that c ...
was a major source of air pollution, and the
calcium sulfide Calcium sulfide is the chemical compound with the formula Calcium, CaSulfide, S. This white material crystallizes in cubes like rock salt. CaS has been studied as a component in a process that would recycle gypsum, a product of flue-gas desulfur ...
byproduct also presented waste disposal issues. However, it remained the major production method for sodium carbonate until the late 1880s.


Solvay process

In 1861, the
Belgian Belgian may refer to: * Something of, or related to, Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Western Europe Western Europe is the region of Europe Europe is a contine ...

Belgian
industrial chemist
Ernest Solvay Ernest Gaston Joseph Solvay (; 16 April 1838 – 26 May 1922) was a Belgian chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist A scientist is a person who conduc ...

Ernest Solvay
developed a method to make sodium carbonate by first reacting
sodium chloride Sodium chloride , commonly known as salt (although sea salt also contains other chemical salt (chemistry), salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With Molar mass, molar ...
,
ammonia Ammonia is a compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fort ...

ammonia
, water, and carbon dioxide to generate
sodium bicarbonate Sodium bicarbonate ( IUPAC name: sodium hydrogen carbonate), commonly known as baking soda or bicarbonate of soda, is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cation (Na+) and a bicarbonate anion ( HCO3 ...

sodium bicarbonate
and
ammonium chloride Ammonium chloride is an 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. However, the distinction is not clearly defi ...

ammonium chloride
: :NaCl + NH3 + CO2 + H2O → NaHCO3 + NH4Cl The resulting sodium bicarbonate was then converted to sodium carbonate by heating it, releasing water and carbon dioxide: :2NaHCO3 → Na2CO3 + H2O + CO2 Meanwhile, the ammonia was regenerated from the ammonium chloride byproduct by treating it with the lime (
calcium oxide Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter ...

calcium oxide
) left over from carbon dioxide generation: :2NH4Cl + CaO → 2NH3 + CaCl2 + H2O The Solvay process recycles its ammonia. It consumes only brine and limestone, and
calcium chloride Calcium chloride is an inorganic compound, a salt with the chemical formula CaCl2. It is a white coloured crystalline solid at room temperature, and it is highly soluble in water. It can be created by neutralising hydrochloric acid with calc ...

calcium chloride
is its only waste product. The process is substantially more economical than the Leblanc process, which generates two waste products,
calcium sulfide Calcium sulfide is the chemical compound with the formula Calcium, CaSulfide, S. This white material crystallizes in cubes like rock salt. CaS has been studied as a component in a process that would recycle gypsum, a product of flue-gas desulfur ...
and
hydrogen chloride The compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fortified with d ...

hydrogen chloride
. The Solvay process quickly came to dominate sodium carbonate production worldwide. By 1900, 90% of sodium carbonate was produced by the Solvay process, and the last Leblanc process plant closed in the early 1920s. The second step of the Solvay process, heating sodium bicarbonate, is used on a small scale by home cooks and in restaurants to make sodium carbonate for culinary purposes (including pretzels and alkali noodles). The method is appealing to such users because sodium bicarbonate is widely sold as baking soda, and the temperatures required ( to ) to convert baking soda to sodium carbonate are readily achieved in conventional kitchen
oven upA double oven A ceramic oven An oven is a tool A tool is an object that can extend an individual's ability to modify features of the surrounding environment. Although many animals use simple tools, only human beings, whose use of stone ...

oven
s.


Hou's process

This process was developed by Chinese chemist
Hou Debang Hou Debang (; 9 August 1890 – 26 August 1974), also known as Hou Qirong () and Hou Te-Pang, was a Chinese chemist and chemical engineer 200px, Chemical engineers design, construct and operate plants. In the field of engineering, a chemical engin ...
in the 1930s. The earlier
steam reforming Steam reforming or steam methane reforming is a method for producing syngas (hydrogen and carbon monoxide) by reaction of hydrocarbons with water. Commonly natural gas is the feedstock. The main purpose of this technology is hydrogen production. The ...
byproduct carbon dioxide was pumped through a saturated solution of
sodium chloride Sodium chloride , commonly known as salt (although sea salt also contains other chemical salt (chemistry), salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With Molar mass, molar ...

sodium chloride
and ammonia to produce sodium bicarbonate by these reactions: : CH4 + 2 + 4 :3 + → 2 : + + : +
NaCl Sodium chloride , commonly known as salt (although sea salt Sea salt is salt that is produced by the evaporation of seawater. It is used as a seasoning in foods, cooking Cooking or cookery is the art, science, and craft of using heat t ...
+ The sodium bicarbonate was collected as a precipitate due to its low solubility and then heated up to approximately or to yield pure sodium carbonate similar to last step of the Solvay process. More sodium chloride is added to the remaining solution of ammonium and sodium chlorides; also, more ammonia is pumped at 30-40 °C to this solution. The solution temperature is then lowered to below 10 °C. Solubility of ammonium chloride is higher than that of sodium chloride at 30 °C and lower at 10 °C. Due to this temperature-dependent solubility difference and the common-ion effect, ammonium chloride is precipitated in a sodium chloride solution. The Chinese name of Hou's process, ''lianhe zhijian fa'' (), means "coupled manufacturing alkali method": Hou's process is coupled to the
Haber process The Haber process, also called the Haber–Bosch process, is an artificial nitrogen fixation process and is the main industrial procedure for the ammonia production, production of ammonia today. It is named after its inventors, the German chemist ...

Haber process
and offers better
atom economy Atom economy (atom efficiency/percentage) is the conversion efficiency of a chemical process in terms of all atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that ha ...

atom economy
by eliminating the production of calcium chloride, since ammonia no longer needs to be regenerated. The byproduct ammonium chloride can be sold as a fertilizer.


See also

*
Natron Natron is a naturally occurring mixture of sodium carbonate decahydrate (sodium carbonate, Na2CO3·10H2O, a kind of soda ash) and around 17% sodium bicarbonate (also called baking soda, NaHCO3) along with small quantities of sodium chloride and ...
* Residual sodium carbonate index *
Sodium bicarbonate Sodium bicarbonate ( IUPAC name: sodium hydrogen carbonate), commonly known as baking soda or bicarbonate of soda, is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cation (Na+) and a bicarbonate anion ( HCO3 ...

Sodium bicarbonate


References


Further reading

* *


External links


American Natural Soda Ash Company



FMC Wyoming Corporation

Use of sodium carbonate in dyeing

Sodium carbonate manufacturing
by synthetic processes
{{DEFAULTSORT:Sodium Carbonate Carbonates Household chemicals Photographic chemicals Sodium compounds E-number additives
soda ash Sodium carbonate, , (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, water-soluble salts that yield moderately alkaline solutions in water. H ...