SODIUM BICARBONATE

CAS No.: 144-55-8
EC No.: 205-633-8

Synonyms:
SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium hydrogen carbonate; 144-55-8; Sodium hydrogencarbonate; Baking soda; Carbonic acid monosodium salt; Sodium acid carbonate; Bicarbonate of soda; Meylon; Sodium hydrocarbonate; Monosodium carbonate; Acidosan; Natron; Neut; Natriumhydrogenkarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; Col-evac; NaHCO3; Soda Mint; Sel De vichy; Natrium bicarbonicum; Soda (van); Jusonin; Soludal; Natrii hydrogencarbonas; Monosodium hydrogen carbonate; Natrium hydrogencarbonicum; Caswell No. 747; Sodium carbonate (Na(HCO3)); sodiumbicarbonate; Carbonic acid sodium salt (1:1); UNII-8MDF5V39QO; Sodium bicarbonate (1:1); SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; MFCD00003528; Carbonic acid, monosodium salt; CCRIS 3064; HSDB 697; EINECS 205-633-8; EPA Pesticide Chemical Code 073505; NSC 134031; 8MDF5V39QO; E500; CHEBI:32139; E 500; E-500; sodium hydrogen-carbonate; Sodium bicarbonate, 99+%, for HPLC; Sodium bicarbonate, 99+%, extra pure; Sodium bicarbonate, 99.5%, for analysis; Sodium bicarbonate in plastic container; Meylon (TN); Sodium bicarbonate, 99.7+%, ACS reagent; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; Sodium bicarbonate [USAN:JAN]; Sodium bicarbonate, 99.5%, for biochemistry; Neut (TN); NSC-134031; Sodium bicarbonate solution; Sodium bicarbonate [USP:JAN]; sodium bicabonate; sodium bicarbonat; bicarbonate sodium; sodiumbi-carbonate; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; sodium bi-carbonate; sodium bicarbonate-; Sodium bi carbonate; natriumhydrogencarbonat; CHNaO3; sodium hydrogencabonate; sodium hydrogencarbonat; sodiumhydrogen carbonate; PubChem23592; sodium hydrogen cabonate; ACMC-20ajp0; hydrogen carbonate sodium; Sodium bicarbonate, USP; sodium hyd-rogencarbonate; sodium-hydrogen-carbonate; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONIATE; EC 205-633-8; CHEMBL1353; KSC175M0P; INS NO.500(II); DTXSID9021269; CTK0H5607; INS-500(II); SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; KS-00000WCP; Sodium bicarbonate (JP17/USP); sodium hydrogen carbonate solution; E-500(II); Sodium bicarbonate -40-+140 mesh; Sodium bicarbonate, Biochemical Grade; AKOS015836321; AKOS015951222; DB01390; LS-2380; Sodium bicarbonate A.C.S. reagent grade; S304; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SC-27096; B7292; FT-0645108; S0561; C12603; D01203; 3-Phenyl-2-thioxotetrahydropyrimidin-4(1H)-one; Q179731; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; Sodium bicarbonate, HPLC, Meets ACS Specifications; Sodium bicarbonate 5% w/v solution in water (+/- 0.3%); Saturated aqueous Sodium bicarbonate solution (~9.6% wt/wt/); SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium hydrogen carbonate; 144-55-8; Sodium hydrogencarbonate; Baking soda; Carbonic acid monosodium salt; Sodium acid carbonate; Bicarbonate of soda; Meylon; Sodium hydrocarbonate; Monosodium carbonate; Acidosan; Natron; Neut; Natriumhydrogenkarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; Col-evac; NaHCO3; Soda Mint; Sel De vichy; Natrium bicarbonicum; Soda (van); Jusonin; Soludal; Natrii hydrogencarbonas; Monosodium hydrogen carbonate; Natrium hydrogencarbonicum; Caswell No. 747; Sodium carbonate (Na(HCO3)); sodiumbicarbonate; Carbonic acid sodium salt (1:1); UNII-8MDF5V39QO; Sodium bicarbonate (1:1); SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; MFCD00003528; Carbonic acid, monosodium salt; CCRIS 3064; HSDB 697; EINECS 205-633-8; EPA Pesticide Chemical Code 073505; NSC 134031; 8MDF5V39QO; E500; CHEBI:32139; E 500; E-500; sodium hydrogen-carbonate; Sodium bicarbonate, 99+%, for HPLC; Sodium bicarbonate, 99+%, extra pure; Sodium bicarbonate, 99.5%, for analysis; Sodium bicarbonate in plastic container; Meylon (TN); Sodium bicarbonate, 99.7+%, ACS reagent; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; Sodium bicarbonate [USAN:JAN]; Sodium bicarbonate, 99.5%, for biochemistry; Neut (TN); NSC-134031; Sodium bicarbonate solution; Sodium bicarbonate [USP:JAN]; sodium bicabonate; sodium bicarbonat; bicarbonate sodium; sodiumbi-carbonate; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; sodium bi-carbonate; sodium bicarbonate-; Sodium bi carbonate; natriumhydrogencarbonat; CHNaO3; sodium hydrogencabonate; sodium hydrogencarbonat; sodiumhydrogen carbonate; PubChem23592; sodium hydrogen cabonate; ACMC-20ajp0; hydrogen carbonate sodium; Sodium bicarbonate, USP; sodium hyd-rogencarbonate; sodium-hydrogen-carbonate; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONIATE; EC 205-633-8; CHEMBL1353; KSC175M0P; INS NO.500(II); DTXSID9021269; CTK0H5607; INS-500(II); SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; KS-00000WCP; Sodium bicarbonate (JP17/USP); sodium hydrogen carbonate solution; E-500(II); Sodium bicarbonate -40-+140 mesh; Sodium bicarbonate, Biochemical Grade; AKOS015836321; AKOS015951222; DB01390; LS-2380; Sodium bicarbonate A.C.S. reagent grade; S304; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; SC-27096; B7292; FT-0645108; S0561; C12603; D01203; 3-Phenyl-2-thioxotetrahydropyrimidin-4(1H)-one; Q179731; SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat; Sodium bicarbonate, HPLC, Meets ACS Specifications; Sodium bicarbonate 5% w/v solution in water (+/- 0.3%); Saturated aqueous Sodium bicarbonate solution (~9.6% wt/wt/); SODIUM BICARBONATE; Sodium Bicarbonate; SODYUM BİKARBONAT; sodyum bikarbonat

SODIUM BICARBONATE

Sodium Bicarbonate is a strong alkali base used in green cleaning products. Often found in powder form, it's used in a wide range of industries, such as in cleaning and personal care products and as a fungicide, microbicide, herbicide, and pH adjuster.

What Is Sodium Bicarbonate?
Sodium Bicarbonate is a chemical compound with the molecular formula Na2CO3. It's commonly referred to as washing soda and is used in cleaning products, glass production, as a food additive, and more.

Synonyms
Sodium Bicarbonate may go by the following names:

Washing soda
Soda ash
DiSodium Bicarbonate
Calcined soda
Carbonic acid disodium salt
Solvay soda
497-19-8
Properties
Sodium Bicarbonate is alkali with a high pH when in concentrated solutions. When it is added to water it breaks down into carbonic acid and sodium hydroxide (lye).

Cleaning Uses
Sodium Bicarbonate is used in several cleaning products, including green cleaning ones, due to its disinfectant properties and ability to cut through grease and soften water. You can find it in laundry detergents, automatic dishwashing detergents, all-purpose cleaners, glass cleaners, stain removers, countertop cleaners, sanitizing sprays, and bleach.

To clean and disinfect with Sodium Bicarbonate, the Environmental Protection Agency (EPA) recommends using 2 ounces per gallon of water.1 This solution can be used to clean hard, non-porous surfaces, such as floors, walls, bathtubs, tile, and grout.

Sodium Bicarbonate is considered an irritant at concentrations below 15 percent and caustic above 15 percent according to the EPA, so keep this in mind when mixing your cleaning solutions with it.1 Wear cleaning gloves and avoid getting it in your eyes or mouth.

Other Uses
In addition to its use in cleaning products, Sodium Bicarbonate is used in:

Chemical manufacturing
Food (e.g., anticaking agent)
Glass manufacturing
Personal care products (e.g., bubble bath, toothpaste, bath salts and soaks, and scrubs)
Pulp and paper products
Swimming pool maintenance (to adjust the pH)
Therapeutic treatments (e.g., to treat dermatitides)
Veterinary medicine treatments (e.g., to treat ringworm, cleanse the skin, and treat eczema)
Product Brands Containing Sodium Bicarbonate
To see if certain products contain Sodium Bicarbonate, try searching the U.S. Department of Health and Human Services Household Products Database, the Environmental Working Group's (EWG) Guide to Healthy Cleaning, the Good Guide, or the EWG's Skin Deep Cosmetic Database. If using the general term "Sodium Bicarbonate" doesn't generate a lot of results, try entering one of its synonyms.

Regulation
When Sodium Bicarbonate is used in personal care products, food, or drugs, it is monitored by the U.S. Food and Drug Administration (FDA). For other uses, such as pesticides and cleaning products, it is monitored by the EPA.

Health and Safety
The EPA considers Sodium Bicarbonate a safe pesticide and the FDA designates it as generally regarded as safe (GRAS). In the 2006 "Reregistration Eligibility Decision (R.E.D) for Sodium Bicarbonate; Weak Mineral Bases," the EPA notes that there are no known human health hazards when Sodium Bicarbonate is used according to EPA and FDA GRAS guidelines and that "no additional information is needed" to assess its safety.1

After seeking immediate medical attention, here are some home care, first-aid guidelines:

Ingestion: Have the person drink a glass of water or milk unless otherwise advised by a health care provider. However, do not have them drink if they are having any of the serious symptoms such as vomiting, convulsions, or drowsiness and have difficulty swallowing. Do not have the person vomit unless to told to do so by a doctor or poison control center.
Eye or skin contact: Flush with plenty of water for a minimum of 15 minutes.
Inhalation: Move the person to fresh air.
Environmental Effects
According to the 2006 R.E.D document, the EPA considers Sodium Bicarbonate to be a naturally occurring chemical found in soil and water and doesn't expect any adverse effects on wildlife or water if low amounts are released into the environment. Therefore, it could be considered green.1

Source
Most of the world's supply of Sodium Bicarbonate is derived from processing trona ore, which is mined in southwest Wyoming.2

Making Sodium Bicarbonate
Interestingly enough, you can also make Sodium Bicarbonate from baking soda by baking it in the oven.

Sodium Bicarbonate
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Not to be confused with Sodium bicarbonate (baking soda), a similar compound.
Sodium Bicarbonate
Skeletal formula of Sodium Bicarbonate
Sample of Sodium Bicarbonate
Names
IUPAC name
Sodium Bicarbonate
Other names
Soda ash, washing soda, soda crystals, sodium trioxocarbonate
Identifiers
CAS Number    
497-19-8 (anhydrous) check
5968-11-6 (monohydrate) ☒
6132-02-1 (decahydrate) ☒
3D model (JSmol)    
Interactive image
ChEBI    
CHEBI:29377 check
ChEMBL    
ChEMBL186314 check
ChemSpider    
9916 check
ECHA InfoCard    100.007.127 Edit this at Wikidata
EC Number    
207-838-8
E number    E500(i) (acidity regulators, ...)
PubChem CID    
10340
RTECS number    
VZ4050000
UNII    
45P3261C7T check
CompTox Dashboard (EPA)    
DTXSID1029621 Edit this at Wikidata
InChI[show]
SMILES[show]
Properties
Chemical formula    Na2CO3
Molar mass    105.9888 g/mol (anhydrous)
286.1416 g/mol (decahydrate)
Appearance    White solid, hygroscopic
Odor    Odorless
Density    
2.54 g/cm3 (25 °C, anhydrous)
1.92 g/cm3 (856 °C)
2.25 g/cm3 (monohydrate)[1]
1.51 g/cm3 (heptahydrate)
1.46 g/cm3 (decahydrate)[2]
Melting point    851 °C (1,564 °F; 1,124 K) (Anhydrous)
100 °C (212 °F; 373 K)
decomposes (monohydrate)
33.5 °C (92.3 °F; 306.6 K)
decomposes (heptahydrate)
34 °C (93 °F; 307 K)
(decahydrate)[2][6]
Solubility in water    Anhydrous, g/100 mL:
7 (0 °C)
16.4 (15 °C)
34.07 (27.8 °C)
48.69 (34.8 °C)
48.1 (41.9 °C)
45.62 (60 °C)
43.6 (100 °C)[3]
Solubility    Soluble in aq. alkalis,[3] glycerol
Slightly soluble in aq. alcohol
Insoluble in CS2, acetone, alkyl acetates, alcohol, benzonitrile, liquid ammonia[4]
Solubility in glycerine    98.3 g/100 g (155 °C)[4]
Solubility in ethanediol    3.46 g/100 g (20 °C)[5]
Solubility in dimethylformamide    0.5 g/kg[5]
Acidity (pKa)    10.33
Magnetic susceptibility (χ)    −4.1·10−5 cm3/mol[2]
Refractive index (nD)    1.485 (anhydrous)
1.420 (monohydrate)[6]
1.405 (decahydrate)
Viscosity    3.4 cP (887 °C)[5]
Structure
Crystal structure    Monoclinic (γ-form, β-form, δ-form, anhydrous)[7]
Orthorhombic (monohydrate, heptahydrate)[1][8]
Space group    C2/m, No. 12 (γ-form, anhydrous, 170 K)
C2/m, No. 12 (β-form, anhydrous, 628 K)
P21/n, No. 14 (δ-form, anhydrous, 110 K)[7]
Pca21, No. 29 (monohydrate)[1]
Pbca, No. 61 (heptahydrate)[8]
Point group    2/m (γ-form, β-form, δ-form, anhydrous)[7]
mm2 (monohydrate)[1]
2/m 2/m 2/m (heptahydrate)[8]
Lattice constant    
a = 8.920(7) Å, b = 5.245(5) Å, c = 6.050(5) Å (γ-form, anhydrous, 295 K)[7]
α = 90°, β = 101.35(8)°, γ = 90°
Coordination geometry    Octahedral (Na+, anhydrous)
Thermochemistry
Heat capacity (C)    112.3 J/mol·K[2]
Std molar
entropy (So298)    135 J/mol·K[2]
Std enthalpy of
formation (ΔfH⦵298)    −1130.7 kJ/mol[2][5]
Gibbs free energy (ΔfG˚)    −1044.4 kJ/mol[2]
Hazards
Main hazards    Irritant
Safety data sheet    MSDS
GHS pictograms    GHS07: Harmful[9]
GHS Signal word    Warning
GHS hazard statements    H319[9]
GHS precautionary statements    P305+351+338[9]
NFPA 704 (fire diamond)    
[11]
NFPA 704 four-colored diamond
010
Lethal dose or concentration (LD, LC):
LD50 (median dose)    4090 mg/kg (rat, oral)[10]
Related compounds
Other anions    Sodium bicarbonate
Other cations    Lithium carbonate
Potassium carbonate
Rubidium carbonate
Caesium carbonate
Related compounds    Sodium sesquicarbonate
Sodium percarbonate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
Sodium Bicarbonate, Na2CO3, (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. 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), Sodium Bicarbonate became known as "soda ash."[12] It is produced in large quantities from sodium chloride and limestone by the Solvay process.

Contents
1    Hydrates
1.1    Washing soda
2    Applications
2.1    Glass manufacture
2.2    Water softening
2.3    Food additive and cooking
2.4    Inexpensive, weak base
2.5    Precursor to other compounds
2.6    Miscellaneous
3    Physical properties
4    Occurrence as natural mineral
5    Production
5.1    Mining
5.2    Barilla and kelp
5.3    Leblanc process
5.4    Solvay process
5.5    Hou's process
6    See also
7    References
8    Further reading
9    External links
Hydrates
Sodium Bicarbonate is obtained as three hydrates and as the anhydrous salt:

Sodium Bicarbonate decahydrate (natron), Na2CO3·10H2O, which readily effloresces to form the monohydrate.
Sodium Bicarbonate heptahydrate (not known in mineral form), Na2CO3·7H2O.
Sodium Bicarbonate monohydrate (thermonatrite), Na2CO3·H2O. Also known as crystal carbonate.
anhydrous Sodium Bicarbonate, also known as calcined soda, is formed by heating the hydrates. It is also formed when sodium hydrogen carbonate is heated (calcined) e.g. in the final step of the 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.[13] 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 Bicarbonate unit ("pentahemihydrate").[14]

Washing soda
Sodium Bicarbonate decahydrate (Na2CO3·10H2O), also known as washing soda, is the most common hydrate of Sodium Bicarbonate containing 10 molecules of water of crystallization. Soda ash is dissolved in water and crystallized to get washing soda.

{displaystyle {ce {Na2CO3 + 10H2O -> Na2CO3.10H2O}}}{displaystyle {ce {Na2CO3 + 10H2O -> Na2CO3.10H2O}}}

It is transparent crystalline solid.
It is one of the few metal carbonates which are soluble in water.
It is alkaline with a pH level of 11; it turns red litmus to blue.
It has detergent properties or cleansing properties, because it can remove dirt and grease from dirty clothes, etc. It attacks dirt and grease to form water soluble products, which are then washed away on rinsing with water.
Applications
Some common applications of Sodium Bicarbonate (or washing soda) include:

Sodium Bicarbonate (or washing soda) is used as a cleansing agent for domestic purposes like washing clothes. Sodium Bicarbonate is a component of many dry soap powders.
It is used for removing temporary and permanent hardness of water.[15] (see water softening).
It is used in the manufacture of glass, soap and paper. (see glass manufacture)
It is used in the manufacture of sodium compounds like borax
Glass manufacture
Sodium Bicarbonate serves as a flux for 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 is added to the melt mixture to make the glass insoluble. Bottle and window glass (soda-lime glass) is made by melting such mixtures of Sodium Bicarbonate, calcium carbonate, and silica sand (silicon dioxide (SiO2)). When these materials are heated, the carbonates release carbon dioxide. In this way, Sodium Bicarbonate is a source of sodium oxide. Soda-lime glass has been the most common form of glass for centuries.[16]

Water softening

Water Hardness in United States
Hard water contains dissolved compounds, usually calcium or magnesium compounds. Sodium Bicarbonate is used for removing temporary and permanent hardness of water.[15]

As Sodium Bicarbonate is water-soluble and magnesium carbonate and calcium carbonate are insoluble, so it is used to soften water by removing Mg2+ and Ca2+. These ions form insoluble solid precipitates upon treatment with carbonate ions:

{displaystyle {ce {Ca^2+ + CO3^2- -> CaCO3}}}{displaystyle {ce {Ca^2+ + CO3^2- -> CaCO3}}}
{displaystyle {ce {Ca^2+(aq) + Na2CO3(aq) -> CaCO3(s) + 2Na+(aq)}}}{displaystyle {ce {Ca^2+(aq) + Na2CO3(aq) -> CaCO3(s) + 2Na+(aq)}}}

Similarly, {displaystyle {ce {Mg^2+(aq) + Na2CO3(aq) -> MgCO3(s) + 2Na+(aq)}}}{displaystyle {ce {Mg^2+(aq) + Na2CO3(aq) -> MgCO3(s) + 2Na+(aq)}}}

The water is softened because it no longer contains dissolved calcium ions and magnesium ions.[15]

Food additive and cooking
Sodium Bicarbonate is a food additive (E500) used as an acidity regulator, anticaking agent, raising agent, and stabilizer. It is one of the components of kansui (かん水), a solution of alkaline salts used to give ramen noodles their characteristic flavor and texture. It is used in the production of snus to stabilize the pH of the final product. Sodium Bicarbonate is used in the production of sherbet powder. The cooling and fizzing sensation results from the endothermic reaction between Sodium Bicarbonate and a weak acid, commonly citric acid, releasing carbon dioxide gas, which occurs when the sherbet is moistened by saliva. In China, it is used to replace lye-water in the crust of traditional Cantonese moon cakes, and in many other Chinese steamed buns and noodles. In cooking, it is sometimes used in place of sodium hydroxide for lyeing, especially with German pretzels and lye rolls. These dishes are treated with a solution of an alkaline substance to change the pH of the surface of the food and improve browning. Sodium Bicarbonate is corrosive to aluminum cookware, utensils and foil. [17]

Inexpensive, weak base
Sodium Bicarbonate is also used as a relatively strong base in various fields. As a common alkali, it is preferred in many chemical processes because it is cheaper than NaOH and far safer to handle. Its mildness especially recommends its use in domestic applications.

For example, it is used as a pH regulator to maintain stable alkaline conditions necessary for the action of the majority of photographic film developing agents. It is also a common additive in swimming pools and aquarium water to maintain a desired pH and carbonate hardness (KH). In dyeing with fiber-reactive dyes, Sodium Bicarbonate (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 pH as a float conditioner besides CaO and other mildly basic compounds.

Precursor to other compounds
Sodium bicarbonate (NaHCO3) or baking soda, also a component in fire extinguishers, is often generated from Sodium Bicarbonate. 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 Bicarbonate is used to make sodium bisulfite (NaHSO3), which is used for the "sulfite" method of separating lignin from cellulose. This reaction is exploited for removing sulfur dioxide 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 Bicarbonate is used by the cotton industry to neutralize the sulfuric acid needed for acid delinting of fuzzy cottonseed.

Miscellaneous
Sodium Bicarbonate 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 to adhere to gelled alginate. Sodium Bicarbonate is used in toothpastes, where it acts as a foaming agent and an abrasive, and to temporarily increase mouth pH.

Sodium Bicarbonate is also used in the processing and tanning of animal hides.[citation needed]

Physical properties
The integral enthalpy of solution of Sodium Bicarbonate is −28.1 kJ/mol for a 10% w/w aqueous solution.[18] The Mohs hardness of Sodium Bicarbonate monohydrate is 1.3.[6]

Occurrence as natural mineral

Structure of monohydrate at 346 K.
Sodium Bicarbonate 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 have been mined from dry lake bottoms in Egypt since ancient times, when natron was used in the preparation of mummies and in the early manufacture of glass.

The anhydrous mineral form of Sodium Bicarbonate is quite rare and called natrite. Sodium Bicarbonate also erupts from 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 Bicarbonate, as well as trona, trisodium hydrogendicarbonate dihydrate, are also known from ultra-alkaline pegmatitic rocks, that occur for example in the Kola Peninsula in Russia.

Extraterrestrially, known Sodium Bicarbonate is rare. Deposits have been identified as the source of bright spots on Ceres, interior material that has been brought to the surface.[19] While there are carbonates on Mars, and these are expected to include Sodium Bicarbonate,[20] deposits have yet to be confirmed, this absence is explained by some as being due to a global dominance of low pH in previously aqueous Martian soil.[21]

Production
Mining
Trona, trisodium hydrogendicarbonate dihydrate (Na3HCO3CO3·2H2O), is mined in several areas of the US and provides nearly all the domestic consumption of Sodium Bicarbonate. Large natural deposits found in 1938, such as the one near Green River, Wyoming, 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 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.[citation needed]

Barilla and kelp
Several "halophyte" (salt-tolerant) plant species and seaweed species can be processed to yield an impure form of Sodium Bicarbonate, and these sources predominated in Europe and elsewhere until the early 19th century. The land plants (typically glassworts or saltworts) or the seaweed (typically Fucus species) were harvested, dried, and burned. The ashes were then "lixiviated" (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, one of the many species of seashore plants harvested for production. "Barilla" is a commercial term applied to an impure form of potash obtained from coastal plants or kelp.[22]

The Sodium Bicarbonate concentration in soda ash varied very widely, from 2–3 percent for the seaweed-derived form ("kelp"), to 30 percent for the best barilla produced from saltwort plants in Spain. Plant and seaweed sources for soda ash, and also for the related alkali "potash", 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.[23]

Leblanc process
Main article: Leblanc process
In 1792, the French chemist Nicolas Leblanc patented a process for producing Sodium Bicarbonate from salt, sulfuric acid, limestone, and coal. In the first step, sodium chloride is treated with sulfuric acid in the Mannheim process. This reaction produces sodium sulfate (salt cake) and hydrogen chloride:

2NaCl + H2SO4 → Na2SO4 + 2HCl
The salt cake and crushed limestone (calcium carbonate) was reduced by heating with coal.[16] This conversion entails two parts. First is the carbothermic reaction whereby the coal, a source of carbon, reduces the sulfate to sulfide:

Na2SO4 + 2C → Na2S + 2CO2
The second stage is the reaction to produce Sodium Bicarbonate and calcium sulfide:

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 Bicarbonate. This extraction process was termed lixiviation.

The hydrochloric acid produced by the Leblanc process was a major source of air pollution, and the calcium sulfide byproduct also presented waste disposal issues. However, it remained the major production method for Sodium Bicarbonate until the late 1880s.[23][24]

Solvay process
Main article: Solvay process
In 1861, the Belgian industrial chemist Ernest Solvay developed a method to make Sodium Bicarbonate by first reacting sodium chloride, ammonia, water, and carbon dioxide to generate sodium bicarbonate and ammonium chloride:[16]

NaCl + NH3 + CO2 + H2O → NaHCO3 + NH4Cl
The resulting sodium bicarbonate was then converted to Sodium Bicarbonate 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) 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 is its only waste product. The process is substantially more economical than the Leblanc process, which generates two waste products, calcium sulfide and hydrogen chloride. The Solvay process quickly came to dominate Sodium Bicarbonate production worldwide. By 1900, 90% of Sodium Bicarbonate was produced by the Solvay process, and the last Leblanc process plant closed in the early 1920s.[16]

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 Bicarbonate 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 (250 °F (121 °C) to 300 °F (149 °C)) to convert baking soda to Sodium Bicarbonate are readily achieved in conventional kitchen ovens.[25]

Hou's process
This process was developed by Chinese chemist Hou Debang in the 1930s. The earlier steam reforming byproduct carbon dioxide was pumped through a saturated solution of sodium chloride and ammonia to produce sodium bicarbonate by these reactions:

CH4 + 2H2O → CO2 + 4H2
3H2 + N2 → 2NH3
NH3 + CO2 + H2O → NH4HCO3
NH4HCO3 + NaCl → NH4Cl + NaHCO3
The sodium bicarbonate was collected as a precipitate due to its low solubility and then heated up to approximately 80 °C (176 °F) or 95 °C (203 °F) to yield pure Sodium Bicarbonate 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 (联合制碱法), means "coupled manufacturing alkali method": Hou's process is coupled to the Haber process and offers better 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
Residual Sodium Bicarbonate index
Sodium bicarbonate