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Sodium bicarbonate (
IUPAC name In chemical nomenclatureA chemical nomenclature is a set of rules to generate systematic names for chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) c ...
: sodium hydrogencarbonate), commonly known as baking soda or bicarbonate of soda, 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 by chemical bonds. A homonuclear molecule, m ...
with the formula NaHCO3. It is a
salt Salt is a mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure fo ...
composed of a
sodium Sodium is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical eleme ...

sodium
cation (
Na+
Na<sup>+</sup>
) and a
bicarbonate In inorganic chemistry, bicarbonate (International Union of Pure and Applied Chemistry, IUPAC-recommended nomenclature: hydrogen carbonate) is an intermediate form in the deprotonation of carbonic acid. It is a Polyatomic ion, polyatomic anion w ...

bicarbonate
anion (
HCO3
HCO<sub>3</sub><sup>−</sup>
). Sodium bicarbonate is a white solid that is
crystal A crystal or crystalline solid is a solid Solid is one of the four fundamental states of matter (the others being liquid A liquid is a nearly incompressible fluid In physics, a fluid is a substance that continually Deformatio ...

crystal
line, but often appears as a fine powder. It has a slightly salty,
alkaline In chemistry, an alkali (; from ar, القلوي ''al-qaly'' "ashes of the saltwort") is a base (chemistry), basic, ionic compound, ionic salt (chemistry), salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as ...

alkaline
taste resembling that of washing soda (
sodium carbonate Sodium carbonate, ·10, (also known as Natrium Carbonate, washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield modera ...

sodium carbonate
). The natural mineral form is
nahcolite Nahcolite is a soft, colourless or white carbonate mineral with the composition of sodium bicarbonate (Sodium, NaHydrogen, HCarbon, COxygen, O3) also called thermokalite. It crystallizes in the monoclinic system. Nahcolite was first described ...
. It is a component 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 ...
and is found dissolved in many mineral springs.


Nomenclature

Because it has long been known and widely used, the salt has many different names such as baking soda, bread soda, cooking soda, and bicarbonate of soda and can often be found near
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 increase ...
in stores. The term ''baking soda'' is more common in the United States, while ''bicarbonate of soda'' is more common in Australia, United Kingdom and Ireland. and in many northern/central European countries it is called ''Natron.'' Abbreviated colloquial forms such as sodium bicarb, bicarb soda, bicarbonate, and bicarb are common. The word ''saleratus'', from
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republic, it became ...
''sal æratus'' (meaning "aerated salt"), was widely used in the 19th century for both sodium bicarbonate and
potassium bicarbonate Potassium bicarbonate (also known as potassium hydrogen carbonate or potassium acid carbonate) is the inorganic compound In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, comp ...

potassium bicarbonate
. Its
E number E numbers ("E" stands for "Europe") are codes for substances used as food additive Food is any substance consumed to provide nutritional support for an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμ ...
food additive code is E500. The prefix ''bi'' in ''bicarbonate'' comes from an
outdated naming system
outdated naming system
predating molecular knowledge in reference to the two molar equivalents of carbon dioxide (known as carbonic acid in the ancient chemistry language) that potassium hydrocarbonate/bicarbonate releases upon decomposition to (di)potassium carbonate and to potassium oxide (potash). The modern chemical formulas of these compounds now express their precise chemical compositions which were unknown when the name ''bi-carbonate of potash'' was coined (see also:
bicarbonate In inorganic chemistry, bicarbonate (International Union of Pure and Applied Chemistry, IUPAC-recommended nomenclature: hydrogen carbonate) is an intermediate form in the deprotonation of carbonic acid. It is a Polyatomic ion, polyatomic anion w ...

bicarbonate
).


Uses


Cooking


Leavening

In cooking, baking soda is primarily used in
baking Baking is a method of preparing food that uses dry heat, typically in an oven, but can also be done in hot ashes, or on hot stones. The most common baked item is bread but many other types of foods are baked. Heat is gradually transferred "fro ...

baking
as a
leavening agent In cooking Cooking, cookery, or culinary arts is the art, science, and craft of using heat In thermodynamics Thermodynamics is a branch of physics that deals with heat, Work (thermodynamics), work, and temperature, and their re ...
. When it reacts with acid, carbon dioxide is released, which causes expansion of the batter and forms the characteristic texture and grain in cakes,
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, wit ...
s,
soda bread Soda bread is a variety of quick bread traditionally made in a variety of cuisines in which sodium bicarbonate (otherwise known as "baking soda", or in Ireland, "bread soda") is used as a leavening agent instead of the traditional yeast. The i ...

soda bread
, and other baked and fried foods. The
acid–base reaction An acid–base reaction is a chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical react ...
can be generically represented as follows: :NaHCO3 + H+ → Na+ + CO2 + H2O Acidic materials that induce this reaction include hydrogen phosphates,
cream of tartar Potassium bitartrate, also known as potassium hydrogen tartrate, with formula K C4H5O6, is a byproduct of winemaking Winemaking or vinification is the production of wine, starting with the selection of the fruit, its Ethanol fermentation, ferme ...
,
lemon The lemon, ''Citrus limon'', is a species of small evergreen In botany Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise ...

lemon
juice,
yogurt Yogurt (; , from tr, yoğurt) also spelled yoghurt, yogourt or yoghourt, is a food produced by bacteria Bacteria (; common noun bacteria, singular bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell ...

yogurt
,
buttermilk Buttermilk is a Fermented milk products, fermented dairy drink. Traditionally, it was the liquid left behind after churning butter out of Microbial food cultures, cultured cream. As most modern butter is not made with cultured cream but uncult ...

buttermilk
,
cocoa CoCoA (Computations in Commutative Algebra) is a free computer algebra system developed by the University of Genova, Italy, used to compute with numbers and polynomials. The CoCoA Library (CoCoALib) is available under GNU General Public License. ...
, and vinegar. Baking soda may be used together with
sourdough Sourdough is a bread Bread is a staple food prepared from a dough of flour and water, usually by baking. Throughout recorded history, it has been a prominent food in large parts of the world. It is one of the oldest man-made foods, having ...

sourdough
, which is acidic, making a lighter product with a less acidic taste. Heat can also by itself cause sodium bicarbonate to act as a raising agent in baking because of
thermal decomposition Thermal decomposition, or thermolysis, is a chemical decompositionChemical decomposition, or chemical breakdown, is the process or effect of simplifying a single chemical entity (normal molecule, reaction intermediate, etc.) into two or more fra ...
, releasing carbon dioxide at temperatures above , as follows: : 2 NaHCO3 → Na2CO3 + H2O + CO2 When used this way on its own, without the presence of an acidic component (whether in the batter or by the use of a baking powder containing acid), only half the available CO2 is released (one CO2 molecule is formed for every two equivalents of NaHCO3). Additionally, in the absence of acid, thermal decomposition of sodium bicarbonate also produces
sodium carbonate Sodium carbonate, ·10, (also known as Natrium Carbonate, washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield modera ...

sodium carbonate
, which is strongly alkaline and gives the baked product a bitter, "soapy" taste and a yellow color. Since the reaction occurs slowly at room temperature, mixtures (cake batter, etc.) can be allowed to stand without rising until they are heated in the oven.


Baking powder

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 increase ...
, also sold for cooking, contains around 30% of bicarbonate, and various acidic ingredients which are activated by the addition of water, without the need for additional acids in the cooking medium. Many forms of baking powder contain sodium bicarbonate combined with calcium acid phosphate,
sodium aluminium phosphate Sodium aluminium phosphate (SAlP) describes 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. However, the distincti ...

sodium aluminium phosphate
, or
cream of tartar Potassium bitartrate, also known as potassium hydrogen tartrate, with formula K C4H5O6, is a byproduct of winemaking Winemaking or vinification is the production of wine, starting with the selection of the fruit, its Ethanol fermentation, ferme ...
. Baking soda is alkaline; the acid used in baking powder avoids a metallic taste when the chemical change during baking creates sodium carbonate.


Pyrotechnics

Sodium bicarbonate is one of the main components of the common "black snake" firework. The effect is caused by the thermal decomposition, which produces carbon dioxide gas to produce a long snake-like ash as a combustion product of the other main component,
sucrose Sucrose is a type of sugar Sugar is the generic name for , soluble s, many of which are used in food. Simple sugars, also called s, include , , and . Compound sugars, also called s or double sugars, are molecules made of two monosacchari ...

sucrose
. Sodium bicarbonate is also used to delay combustion reactions by releasing CO2 and H2O when heated, both of which are flame retardants.


Mild disinfectant

It has weak
disinfectant A disinfectant is a chemical A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ...
properties, and it may be an effective
fungicide Fungicides are biocidal 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 substance that has mass and takes up space by hav ...
against some organisms. Because baking soda will absorb musty smells, it has become a reliable method for
used book Image:London books.JPG, The South Bank Book Market in front of the National Film Theatre, London, England, in October 2004 A used book or secondhand book is a book which has been owned before by an owner other than the publisher or retailer, usuall ...
sellers when making books less malodorous.


Fire extinguisher

Sodium bicarbonate can be used to extinguish small grease or electrical fires by being thrown over the fire, as heating of sodium bicarbonate releases carbon dioxide. However, it should not be applied to fires in
deep fryer A domestic deep fryerA deep fryer is a kitchen appliance A typical Hoosier cabinet of the 1920s A kitchen is a room or part of a room used for cooking Cooking or cookery is the art, science, and craft of using heat to Outline of food prepa ...
s; the sudden release of gas may cause the grease to splatter. Sodium bicarbonate is used in BC dry chemical
fire extinguishers A fire extinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situations. It is not intended for use on an out-of-control fire, such as one which has reached the ceiling, endangers the use ...

fire extinguishers
as an alternative to the more corrosive
diammonium phosphate Diammonium phosphate (DAP; IUPAC name diammonium hydrogen phosphate; chemical formula (NH4)2(HPO4) is one of a series of water-soluble ammonium phosphate salt (chemistry), salts that can be produced when ammonia reacts with phosphoric acid. Solid ...

diammonium phosphate
in ABC extinguishers. The alkaline nature of sodium bicarbonate makes it the only dry chemical agent, besides
Purple-K Purple-K, also known as PKP, is a dry-chemical fire suppression agent used in some dry chemical fire extinguishers. It is the second most effective dry chemical in fighting Class B fire, class B (flammable liquid) fires after Monnex (potassium allop ...
, that was used in large-scale fire suppression systems installed in commercial kitchens. Because it can act as an alkali, the agent has a mild
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
effect on hot grease, which forms a smothering, soapy foam.


Neutralization of acids

Sodium bicarbonate reacts spontaneously with acids, releasing CO2 gas as a reaction product. It is commonly used to neutralize unwanted acid solutions or acid spills in chemical laboratories. It is not appropriate to use sodium bicarbonate to neutralize base even though it is
amphoteric In chemistry, an amphoteric compound is a molecule or ion that can react both as an acid An acid is a molecule or ion An ion () is a particle In the Outline of physical science, physical sciences, a particle (or corpuscule in older ...
, reacting with both acids and bases.


Agriculture

Sodium bicarbonate when applied on leaves, can prevent the growth of fungi; however, does not kill the fungus. Excessive amount of sodium bicarbonate can cause discolouration of fruits (two percent solution) and chlorosis (one percent solution).


Medical uses and health

Sodium bicarbonate mixed with water can be used as an
antacid An antacid is a substance which neutralizes stomach acidity and is used to relieve heartburn Heartburn, also known as pyrosis, cardialgia or acid indigestion, is a burning sensation in the central chest or upper central abdomen. The disc ...
to treat acid indigestion and
heartburn Heartburn, also known as pyrosis, cardialgia or acid indigestion, is a burning sensation in the central chest or upper central abdomen. The discomfort often rises in the chest and may radiate to the neck, throat, or angle of the arm. Heartbur ...
. Its reaction with
stomach acidGastric acid, gastric juice, or stomach acid, is a digestive fluid formed within the gastric mucosa, stomach lining. With a pH between 1 and 3, gastric acid plays a key role in digestion of proteins by activating digestive enzymes, which together bre ...
produces salt, water, and
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pare ...

carbon dioxide
: :NaHCO3 + HCl → NaCl + H2O + CO2(g) A mixture of sodium bicarbonate and
polyethylene glycol Polyethylene glycol (PEG; ) is a polyether Ethers are a class of 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 ...

polyethylene glycol
such as PegLyte, dissolved in water and taken orally, is an effective gastrointestinal lavage preparation and
laxative Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements frame, Anatomy of the anus and rectum Defecation is the final act of digestion Digestion is the breakdown of large insoluble food Food ...
prior to gastrointestinal surgery,
gastroscopy Esophagogastroduodenoscopy (EGD; ), also called by various other names, is a diagnostic endoscopic procedure that visualizes the upper part of the gastrointestinal tract The gastrointestinal tract, (GI tract, GIT, digestive tract, digestion ...
, etc.
Intravenous sodium bicarbonate Intravenous sodium bicarbonate, also known as sodium hydrogen carbonate, is a medication primarily used to treat severe metabolic acidosis Metabolic acidosis is a serious electrolyte disorder characterized by an imbalance in the body's acid-ba ...
in an aqueous solution is sometimes used for cases of
acidosis Acidosis is a process causing increased acidity An acid is a molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is ...

acidosis
, or when insufficient sodium or bicarbonate ions are in the blood. In cases of respiratory acidosis, the infused bicarbonate ion drives the carbonic acid/bicarbonate buffer of plasma to the left, and thus raises the pH. For this reason, sodium bicarbonate is used in medically supervised
cardiopulmonary resuscitation Cardiopulmonary resuscitation (CPR) is an emergency procedure An emergency procedure is a plan of actions to be conducted in a certain order or manner, in response to a specific class of reasonably foreseeable emergency, a situation that poses ...
. Infusion of bicarbonate is indicated only when the blood pH is markedly low (< 7.1–7.0). HCO3 is used for treatment of
hyperkalemia Hyperkalemia is an elevated level of potassium Potassium is a chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the propertie ...
, as it will drive K+ back into cells during periods of acidosis. Since sodium bicarbonate can cause
alkalosis Alkalosis is the result of a process reducing hydrogen ion A hydrogen ion is created when a hydrogen atom loses or gains an electron. A positively charged hydrogen ion (or proton) can readily combine with other particles and therefore is only seen ...
, it is sometimes used to treat aspirin overdoses. Aspirin requires an acidic environment for proper absorption, and a basic environment will diminish aspirin absorption in cases of overdose. Sodium bicarbonate has also been used in the treatment of
tricyclic antidepressant overdose Tricyclic antidepressant overdose is poisoning caused by excessive medication of the tricyclic antidepressant (TCA) type. Symptoms may include elevated body temperature, blurred vision, dilated pupils, sleepiness, confusion, seizures A seiz ...
. It can also be applied topically as a paste, with three parts baking soda to one part water, to relieve some kinds of insect bites and stings (as well as accompanying swelling). Some alternative practitioners, such as Tullio Simoncini, have promoted baking soda as a cancer cure, which the American Cancer Society has warned against due to both its unproven effectiveness and potential danger in use.
Edzard Ernst Edzard Ernst (born 30 January 1948) is a retired academic physician and researcher specializing in the study of complementary and alternative medicine Alternative medicine is any practice that aims to achieve the healing effects of medicine ...

Edzard Ernst
has called the promotion of sodium bicarbonate as a cancer cure "one of the more sickening alternative cancer scams I have seen for a long time". Sodium bicarbonate can be added to
local anesthetics A local anesthetic (LA) is a medication A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to medical diagnosis, diagnose, cure, therapy, treat, or preventive medicine, preven ...
, to speed up the onset of their effects and make their injection less painful. It is also a component of Moffett's solution, used in surgery. It has been proposed that acidic diets weaken bones. One systematic meta-analysis of the research shows no such effect. Another also finds that there is no evidence that alkaline diets improve bone health, but suggests that there "may be some value" to alkaline diets for other reasons.
Antacid An antacid is a substance which neutralizes stomach acidity and is used to relieve heartburn Heartburn, also known as pyrosis, cardialgia or acid indigestion, is a burning sensation in the central chest or upper central abdomen. The disc ...
(such as baking soda) solutions have been prepared and used by protesters to alleviate the effects of exposure to
tear gas Tear gas, also known as a lachrymator agent or lachrymator (from the Latin ''lacrima'' meaning "tears, tear"), sometimes colloquially known as mace (spray), "mace" after an early commercial aerosol, is a chemical weapon that stimulates the ne ...
during protests. Similarly to its use in baking, sodium bicarbonate is used together with a mild acid such as
tartaric acid Tartaric acid is a white, crystalline organic acid that occurs naturally in many fruits, most notably in grapes, but also in bananas, tamarinds, and citrus. Its salt (chemistry), salt, potassium bitartrate, commonly known as cream of tartar, dev ...

tartaric acid
as the excipient in effervescent tablets: when such a tablet is dropped in a glass of water, the carbonate leaves the reaction medium as carbon dioxide gas (HCO3 + H+ → H2O + CO2↑ or, more precisely, HCO3 + H3O+ → 2 H2O + CO2↑). This makes the tablet disintegrate, leaving the medication suspended and/or dissolved in the water together with the resulting salt (in this example,
sodium tartrate Sodium tartrate (Na2C4H4O6) is a salt used as an emulsion, emulsifier and a binding agent in food products such as Jelly (fruit preserves), jellies, margarine, and sausage casings. As a food additive, it is known by the E number E335. Because it ...

sodium tartrate
).


Personal hygiene

Sodium bicarbonate is also used as an ingredient in some mouthwashes. It has anticaries and abrasive properties. It works as a mechanical cleanser on the teeth and gums, neutralizes the production of acid in the mouth, and also acts as an
antiseptic Antiseptics (from Greek ἀντί ''anti'', "against" and σηπτικός ''sēptikos'', "putrefactive") are antimicrobial, antimicrobial substances that are applied to living biological tissue, tissue/skin to reduce the possibility of infection ...

antiseptic
to help prevent infections. Sodium bicarbonate in combination with other ingredients can be used to make a dry or wet
deodorant A deodorant is a substance applied to the body to prevent or mask body odor due to bacterial breakdown of perspiration in the armpits, groin, and foot, feet, and in some cases Vagina#Secretions, vaginal secretions. A subclass of deodorants, called ...

deodorant
. Sodium bicarbonate may be used as a buffering agent, combined with table salt, when creating a solution for . It is used in eye hygiene to treat
blepharitis Blepharitis is one of the most common ocular conditions characterized by inflammation, scaling, reddening, and crusting of the eyelid. This condition may also cause burning, itching, or a grainy sensation when introducing foreign objects or substan ...

blepharitis
. This is done by addition of a teaspoon of sodium bicarbonate to cool water that was recently boiled, followed by gentle scrubbing of the eyelash base with a cotton swab dipped in the solution.


Veterinary uses

Sodium bicarbonate is used as a cattle feed supplement, in particular as a
buffering agent A buffer solution (more precisely, pH buffer or hydrogen ion A hydrogen ion is created when a hydrogen Hydrogen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical ...
for the
rumen The rumen, also known as a paunch, is the largest stomach compartment in ruminants and the larger part of the reticulorumen, which is the first chamber in the alimentary canal of ruminant animals. The rumen's microbial favoring environment allows ...
.


Cleaning agent

Sodium bicarbonate is used in a process for removing paint and corrosion called sodablasting. As a blasting medium, sodium bicarbonate is used to remove surface contamination from softer and less resilient
substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached **Substrate (locomotion), the surface over which an organism loco ...
s such as aluminium, copper or timber which could be damaged by silica sand abrasive media. A manufacturer recommends a paste made from baking soda with minimal water as a gentle scouring powder, and is useful in removing surface rust, as the rust forms a water-soluble compound when in a concentrated alkaline solution; cold water should be used, as hot-water solutions can corrode steel. Sodium bicarbonate attacks the thin protective oxide layer that forms on aluminium, making it unsuitable for cleaning this metal. A solution in warm water will remove the
tarnish Tarnish is a thin layer of corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable form such as oxide of rutile. Ti(IV) centers are grey; oxygen centers are red. Notice that oxygen forms three bonds ...
from silver when the silver is in contact with a piece of
aluminium foil Aluminium (aluminum in American and Canadian English Canadian English (CanE, CE, en-CA) is the set of varieties of the English language English is a West Germanic languages, West Germanic language first spoken in History of Angl ...
. Baking soda is commonly added to washing machines as a replacement for water softener and to remove odors from clothes. It is also almost as effective in removing heavy tea and coffee stains from cups as
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
, when diluted with warm water. During the
Manhattan Project The Manhattan Project was a research and development Research and development (R&D, R+D), known in Europe as research and technological development (RTD), is the set of innovative activities undertaken by corporations or governments in ...
to develop the nuclear bomb in the early 1940s, the chemical toxicity of uranium was an issue. Uranium oxides were found to stick very well to cotton cloth, and did not wash out with soap or laundry detergent. However, the uranium would wash out with a 2% solution of sodium bicarbonate. Clothing can become contaminated with toxic dust of
depleted uranium Depleted uranium (DU; also referred to in the past as Q-metal, depletalloy or D-38) is uranium Uranium is a chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is ...
(DU), which is very dense, hence used for counterweights in a civilian context, and in armour-piercing projectiles. DU is not removed by normal laundering; washing with about 6 ounces (170 g) of baking soda in 2 gallons (7.5 L) of water will help to wash it out.


Odor control

It is often claimed that baking soda is an effective odor remover, and it is often recommended that an open box be kept in the refrigerator to absorb odor. This idea was promoted by the leading U.S. brand of baking soda,
Arm & Hammer Arm & Hammer is a brand of baking soda-based consumer products marketed by Church & Dwight, a major American manufacturer of household products. The logo of the brand depicts the ancient symbol of a arm-and-hammer symbol, muscular arm holding a h ...
, in an advertising campaign starting in 1972. Though this campaign is considered a classic of marketing, leading within a year to more than half of American refrigerators containing a box of baking soda, there is little evidence that it is in fact effective in this application.


Chemistry

Sodium bicarbonate is an
amphoteric In chemistry, an amphoteric compound is a molecule or ion that can react both as an acid An acid is a molecule or ion An ion () is a particle In the Outline of physical science, physical sciences, a particle (or corpuscule in older ...

amphoteric
compound. Aqueous solutions are mildly
alkaline In chemistry, an alkali (; from ar, القلوي ''al-qaly'' "ashes of the saltwort") is a base (chemistry), basic, ionic compound, ionic salt (chemistry), salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as ...

alkaline
due to the formation of
carbonic acid In chemistry, carbonic acid is a dibasic acid with the chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and s ...

carbonic acid
and
hydroxide Hydroxide is a diatomic anion with chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other sym ...
ion: :HCO + H2O → + OH Sodium bicarbonate can often be used as a safer alternative 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
, and as such can be used as a wash to remove any acidic impurities from a "crude" liquid, producing a purer sample. Reaction of sodium bicarbonate and an
acid An acid is a or capable of donating a (hydrogen ion H+) (a ), or, alternatively, capable of forming a with an (a ). The first category of acids are the proton donors, or s. In the special case of , proton donors form the H3O+ and are ...
produces a salt and carbonic acid, which readily decomposes to carbon dioxide and water: :NaHCO3 + HCl → NaCl + H2CO3 :H2CO3 → H2O + CO2(g) Sodium bicarbonate reacts with
acetic acid Acetic acid , systematically named ethanoic acid , is a colourless liquid organic compound with the chemical formula CH3COOH (also written as CH3CO2H, C2H4O2, or HC2H3O2). Vinegar is no less than 4% acetic acid by volume, making acetic acid ...

acetic acid
(found in vinegar), producing
sodium acetate Sodium acetate, NaCH3COO, also abbreviated NaOAc, is the sodium Sodium is a chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a ...
, water, and
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pare ...

carbon dioxide
: :NaHCO3 + CH3COOH → CH3COONa + H2O + CO2(g) Sodium bicarbonate reacts with bases such as
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
to form carbonates: :NaHCO3 + NaOH → Na2CO3 + H2O


Thermal decomposition

At temperatures from 80–100 °C (176–212 °F), sodium bicarbonate gradually decomposes into
sodium carbonate Sodium carbonate, ·10, (also known as Natrium Carbonate, washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield modera ...

sodium carbonate
, water, and carbon dioxide. The conversion is faster at : : 2 NaHCO3 → Na2CO3 + H2O + CO2 Most bicarbonates undergo this
dehydration reaction In chemistry, a dehydration reaction, also known as Zimmer's hydrogenesis, is a chemical reaction that involves the loss of water from the reacting molecule or ion. It is the most common type of condensation reaction. Dehydration reactions are co ...
. Further heating converts the carbonate into the
oxide An oxide () 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 by che ...
(above ): : Na2CO3 → Na2O + CO2 These conversions are relevant to the use of NaHCO3 as a fire-suppression agent ("BC powder") in some dry-powder
fire extinguisher A fire extinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situations. It is not intended for use on an out-of-control fire, such as one which has reached the ceiling, endangers the user ...

fire extinguisher
s.


Stability & Shelf Life

If kept cool (room temperature) and dry (an airtight container is recommended to keep out moist air), sodium bicarbonate can be kept without a significant amount of decomposition for at least two or three years.


History

The word ''natron'' has been in use in many languages throughout
modern timesModern Times may refer to modern history. Modern Times may also refer to: Music * Modern Times (band), a band from Luxembourg * Modern Times (Al Stewart album), ''Modern Times'' (Al Stewart album), a 1975 album by Al Stewart * Modern Times (Bob Dy ...
(in the forms of ''anatron'', ''natrum'' and ''natron'') and originated (like Spanish, French and English ''natron'' as well as '
sodium Sodium is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical eleme ...

sodium
') via Arabic ''naṭrūn'' (or ''anatrūn''; cf. the Lower Egyptian “Natrontal”
Wadi El Natrun Wadi El Natrun ( ar, وادي النطرون "Valley of Natron"; cop, Ϣⲓϩⲏⲧ ''Šihēt'', "measure of the hearts") is a Depression (geology), depression in northern Egypt that is located below sea level and below the Nile River level. Th ...
, where a mixture of sodium carbonate and sodium hydrogen carbonate for the dehydration of mummies was used ) from Greek ''nítron (νίτρον)'' (Herodotus; Attic ''lítron (λίτρον)''), which can be traced back to ancient Egyptian ''ntr''. The Greek ''nítron'' (soda, soda, saltpeter) was also used in Latin ''(sal) nitrum'' and in German ''Salniter'' (the source of ''Nitrogen'', ''Nitrat'' etc.). In 1791, 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 ...
produced sodium carbonate, also known as
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 ...
. The pharmacist Valentin Rose the Younger is credited with the discovery of sodium bicarbonate 1801 in Berlin. In 1846, two American bakers, John Dwight and
Austin Church Austin Church (January 8, 1799 – August 7, 1879) was an American medical doctor and a pioneer of Sodium bicarbonate, bicarbonate of soda manufacturing. He was a co-founder of the company that first developed the product in America from chemical ...
, established the first factory in the United States to produce baking soda from sodium carbonate and
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pare ...

carbon dioxide
. ''Saleratus'', potassium or sodium bicarbonate, is mentioned in the novel ''Captains Courageous'' by Rudyard Kipling as being used extensively in the 1800s in commercial fishing to prevent freshly caught fish from spoiling. In 1919, a U.S. Senator declared that bicarbonate of soda could cure the Spanish flu. In the midst of the debate on 26 January 1919, Senator Overman interrupted the discussion to announce the discovery of a cure. "I want to say, for the benefit of those who are making this investigation," he reported, "that I was told by a judge of a superior court in the mountain country of North Carolina they have discovered a remedy for this disease." The purported cure implied a critique of modern science and an appreciation for the simple wisdom of simple people. "They say that common baking soda will cure the disease," he continued, "that they have cured it with it, that they have no deaths up there at all; they use common baking soda, which cures the disease."


Production

Sodium bicarbonate is produced industrially from
sodium carbonate Sodium carbonate, ·10, (also known as Natrium Carbonate, washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield modera ...

sodium carbonate
: :Na2CO3 + CO2 + H2O → 2 NaHCO3 It is produced on the scale of about 100,000 tonnes/year (as of 2001) with a worldwide production capacity of 2.4 million tonnes per year (as of 2002).Page 45, section 3.6.2.1 o
"Process Best Practices Reference Document (BREF) for Soda Ash,"
report produced by th
European Soda Ash Producer's Association
March 2004. Archived at WebCite fro
this original URL
on 1 March 2008.
Commercial quantities of baking soda are also produced by a similar method: soda ash, mined in the form of the ore trona, is dissolved in water and treated with carbon dioxide. Sodium bicarbonate precipitates as a solid from this solution. Regarding the Solvay process, sodium bicarbonate is an intermediate in the reaction of sodium chloride, ammonia, and
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pare ...

carbon dioxide
. The product however shows low purity (75pc). : sodium chloride, NaCl + carbon dioxide, CO2 + ammonia, NH3 + water, H2O → NaHCO3 + ammonium chloride, NH4Cl Although of no practical value, NaHCO3 may be obtained by the reaction of carbon dioxide with an aqueous solution of sodium hydroxide: :CO2 + NaOH → NaHCO3


Mining

Naturally occurring deposits of nahcolite (NaHCO3) are found in the Eocene-age (55.8–33.9 Mya) Green River Formation, Piceance Basin in Colorado. Nahcolite was deposited as beds during periods of high evaporation in the basin. It is commercially mined using common underground mining techniques such as bore, drum, and longwall mining in a fashion very similar to coal mining. It is also produced by solution mining, pumping heated water through nahcolite beds and crystalizing the dissolved nahcolite through a cooling crystallization process.


In popular culture

Sodium bicarbonate, as "bicarbonate of soda", was a frequent source of punch lines for Groucho Marx in Marx Brothers movies. In ''Duck Soup (1933 film), Duck Soup'', Marx plays the leader of a nation at war. In one scene, he receives a message from the battlefield that his general is reporting a gas attack, and Groucho tells his aide: "Tell him to take a teaspoonful of bicarbonate of soda and a half a glass of water." In ''A Night at the Opera (film), A Night at the Opera'', Groucho's character addresses the opening night crowd at an opera by saying of the lead tenor: "Signor Lassparri comes from a very famous family. His mother was a well-known bass singer. His father was the first man to stuff spaghetti with bicarbonate of soda, thus causing and curing indigestion at the same time." In the Joseph L. Mankewicz classic ''All About Eve'', the Max Fabian character (Gregory Ratoff) has an extended scene with Margo Channing (Bette Davis) in which, suffering from heartburn, he requests and then drinks bicarbonate of soda, eliciting a prominent burp. Channing promises to always keep a box of bicarb with Max's name on it.


See also

* Carbonic acid * List of ineffective cancer treatments * List of minerals * Natron * Natrona (disambiguation) * Trona


References


Bibliography

*


External links


International Chemical Safety Card 1044
{{Authority control Acid salts Antacids Bases (chemistry) Bicarbonates Chemical substances for emergency medicine Fire suppression agents Household chemicals Leavening agents Sodium compounds E-number additives Powders Food powders