Sodium bicarbonate

Sodium bicarbonate
IUPAC name Sodium hydrogen carbonate
Other names Baking soda, bicarbonate of soda, nahcolite, sodium bicarbonate, sodium hydrogencarbonate
Identifiers
CAS number	144-55-8 Y
PubChem	516892
ChemSpider	8609 Y
UNII	8MDF5V39QO Y
EC number	205-633-8
DrugBank	DB01390
KEGG	C12603 Y
MeSH	Sodium+bicarbonate
ChEBI	CHEBI:32139 Y
ChEMBL	CHEMBL1353 Y
RTECS number	VZ0950000
ATC code	B05CB04,B05XA02
Beilstein Reference	4153970
Jmol-3D images	Image 1
SMILES [Na+].OC([O-])=O
InChI InChI=1S/CH2O3.Na/c2-1(3)4;/h(H2,2,3,4);/q;+1/p-1 Y Key: UIIMBOGNXHQVGW-UHFFFAOYSA-M Y InChI=1/CH2O3.Na/c2-1(3)4;/h(H2,2,3,4);/q;+1/p-1 Key: UIIMBOGNXHQVGW-REWHXWOFAQ
Properties
Molecular formula	CHNaO3
Molar mass	84.01 g mol−1
Exact mass	83.982338573 g mol−1
Appearance	White crystals
Density	2.20 g cm−3[1]
Melting point	50 °C, 323 K, 122 °F (decomposes)
Solubility in water	69 g/L (0 °C)[2] 96 g/l (20 °C)[3] 165 g/l (60 °C)[3] 236 g/L (100 °C)[2]
log P	-0.82
Acidity (pKa)	10.329[4] 6.351 (carbonic acid)[4]
Refractive index (nD)	1.3344
Pharmacology
Routes of administration	Intravenous, oral
Hazards
MSDS	External MSDS
Main hazards	Causes serious eye irritation
NFPA 704	0 1 0
LD50	4.22 g kg−
Related compounds
Other anions	Sodium carbonate
Other cations	Ammonium bicarbonate Potassium bicarbonate
Related compounds	Sodium bisulfate Sodium hydrogen phosphate
Y bicarbonate (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula Na HCO₃. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda (sodium carbonate). The natural mineral form is nahcolite. It is a component of the mineral natron and is found dissolved in many mineral springs. It is found in dissolved form in bile, where it serves to neutralize the acidity of the hydrochloric acid produced by the stomach, and is excreted into the duodenum of the small intestine via the bile duct. It is also produced artificially.

Since it has long been known and is widely used, the salt has many related names such as baking soda, bread soda, cooking soda, and bicarbonate of soda. In colloquial usage, its name is shortened to sodium bicarb, bicarb soda, or simply bicarb. The word saleratus, from Latin sal æratus meaning aerated salt, was widely used in the 19th century for both sodium bicarbonate and potassium bicarbonate. The term has now fallen out of common usage.

History

The ancient Egyptians used natural deposits of natron, a mixture consisting mostly of sodium carbonate decahydrate, and sodium bicarbonate. The natron was used as a cleansing agent like soap.

In 1791, a French chemist, Nicolas Leblanc, produced sodium carbonate, also known as soda ash. In 1846, two New York bakers, John Dwight and Austin Church, established the first factory to develop baking soda from sodium carbonate and carbon dioxide.^[5]

This compound, referred to as saleratus, is mentioned in the famous novel Captains Courageous by Rudyard Kipling as being used extensively in the 1800's in commercial fishing to prevent freshly-caught fish from spoiling.^[6]

Production

Main article: Solvay process

NaHCO₃ is mainly prepared by the Solvay process, which is the reaction of sodium chloride, ammonia, and carbon dioxide in water. Calcium carbonate is used as the source of CO₂ and the resultant calcium oxide is used to recover the ammonia from the Ammonium Chloride It is produced on the scale of about 100,000 tonnes/year (as of 2001).^[7]

NaHCO₃ may be obtained by the reaction of carbon dioxide with an aqueous solution of sodium hydroxide. The initial reaction produces sodium carbonate:

CO₂ + 2 NaOH → Na₂CO₃ + H₂O

Further addition of carbon dioxide produces sodium bicarbonate, which at sufficiently high concentration will precipitate out of solution:

Na₂CO₃ + CO₂ + H₂O → 2 NaHCO₃

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 method:

Na₂CO₃ + CO₂ + H₂O → 2 NaHCO₃

Mining

Naturally occurring deposits of nahcolite (NaHCO₃) are found in the Eocene-age (55.8–33.9 Ma) 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 in-situ leach techniques involving dissolution of the nahcolite by heated water that is pumped through the nahcolite beds and reconstituted through a natural cooling crystallization process.

Chemistry

Sodium bicarbonate is an amphoteric compound. Aqueous solutions are mildly alkaline due to the formation of carbonic acid and hydroxide ion:

HCO−
3 + H₂O → H₂CO₃ + OH⁻

Sodium bicarbonate 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 produce 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 (found in vinegar), producing sodium acetate, water, and carbon dioxide:

NaHCO₃ + CH₃COOH → CH₃COONa + H₂O + CO₂(g)

Sodium bicarbonate reacts with bases such as sodium hydroxide to form carbonates:

NaHCO₃ + NaOH → Na₂CO₃ + H₂O

Sodium bicarbonate reacts with carboxyl groups in proteins to give a brisk effervescence from the formation of CO₂. This reaction is used to test for the presence of carboxylic groups in protein.^{[citation needed]}

Thermal decomposition

Above 70 °C, sodium bicarbonate gradually decomposes into sodium carbonate, water and carbon dioxide. The conversion is fast at 200 °C:^[8]

2 NaHCO₃ → Na₂CO₃ + H₂O + CO₂

Most bicarbonates undergo this dehydration reaction. Further heating converts the carbonate into the oxide (at ca. 1000 °C):

Na₂CO₃ → Na₂O + CO₂

These conversions are relevant to the use of NaHCO₃ as a fire-suppression agent ("BC powder") in some dry powder fire extinguishers.

Applications

Cooking

Main article: Leavening agent

Sodium bicarbonate, referred to as "baking soda" is primarily used in cooking (baking), as a leavening agent. It reacts with acidic components in batters, releasing carbon dioxide, which causes expansion of the batter and forms the characteristic texture and grain in pancakes, cakes, quick breads, and other baked and fried foods. Acidic compounds that induce this reaction include phosphates, cream of tartar, lemon juice, yogurt, buttermilk, cocoa, vinegar, etc. Sodium bicarbonate can be substituted for baking powder provided sufficient acid reagent is also added to the recipe.^[9] Many forms of baking powder contain sodium bicarbonate combined with one or more acidic phosphates (especially good)^{[citation needed]} or cream of tartar.

Sodium bicarbonate was sometimes used in cooking vegetables, to make them softer, although this has gone out of fashion, as most people now prefer firmer vegetables that contain more nutrients. However, it is still used in Asian cuisine to tenderise meats. Bicarb may react with acids in food, including Vitamin C (L-ascorbic acid). It is also used in breadings such as for fried foods to enhance crispness.

Thermal decomposition causes sodium bicarbonate alone to act as a raising agent by releasing carbon dioxide at baking temperatures. The carbon dioxide production starts at temperatures above 80 °C. The mixture for cakes using this method can be allowed to stand before baking without any premature release of carbon dioxide.

Neutralization of acids and bases

Many laboratories keep a bottle of sodium bicarbonate powder within easy reach, because sodium bicarbonate is amphoteric, reacting with acids and bases. Furthermore, as it is relatively innocuous in most situations, there is no harm in using excess sodium bicarbonate. Also, sodium bicarbonate powder may be used to smother a small fire, as heating of sodium bicarbonate releases carbon dioxide.^[10]

A wide variety of applications follows from its neutralization properties, including reducing the spread of white phosphorus from incendiary bullets inside an afflicted soldier's wounds.^{[11][medical citation needed]} Sodium bicarbonate can be added as a simple solution for raising the pH balance of water (increasing total alkalinity) where high levels of chlorine (2–5 ppm) are present as in swimming pools and aquariums.^[12]

Medical uses

Sodium bicarbonate is used in an aqueous solution as an antacid taken orally to treat acid indigestion and heartburn.^[13] It may also be used in an oral form to treat chronic forms of metabolic acidosis such as chronic renal failure and renal tubular acidosis. Sodium bicarbonate may also be useful in urinary alkalinization for the treatment of aspirin overdose and uric acid renal stones. It is used as the medicinal ingredient in gripe water for infants.^[14]

Sodium bicarbonate has been known to be used in first aid, in treating scalding, to prevent blistering and scarring with instructions to cover the scalded area with a liberal layer of sodium bicarbonate and water paste and seek medical assistance. This is due to the endothermic reaction that occurs between sodium bicarbonate and water and sodium bicarbonates mild antiseptic properties^{[15][medical citation needed]}

Intravenous sodium bicarbonate is an aqueous solution that is sometimes used for cases of acidosis, or when there are insufficient sodium or bicarbonate ions in the blood.^[16] 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. It is for this reason that sodium bicarbonate is used in medically supervised cardiopulmonary resuscitation. Infusion of bicarbonate is indicated only when the blood pH is marked (<7.1–7.0) low.^[17]

It is used as well for treatment of hyperkalemia. Since sodium bicarbonate can cause alkalosis, it is sometimes used to treat aspirin overdoses. Aspirin requires an acidic environment for proper absorption, and the basic environment diminishes aspirin absorption in the case of an overdose. Sodium bicarbonate has also been used in the treatment of tricyclic antidepressant overdose.^[18] It can also be applied topically as a paste, with three parts baking soda to one part water, to relieve insect bites.^[19]

Adverse reactions to the administration of sodium bicarbonate can include metabolic alkalosis, edema due to sodium overload, congestive heart failure, hyperosmolar syndrome, hypervolemic hypernatremia, and hypertension due to increased sodium. In patients consuming a high-calcium or dairy-rich diet, calcium supplements, or calcium-containing antacids such as calcium carbonate (e.g., Tums), the use of sodium bicarbonate can cause milk-alkali syndrome, which can result in metastatic calcification, kidney stones, and kidney failure.

Sodium bicarbonate can be used to cover an allergic reaction of poison ivy, oak, or sumac to relieve some of the itching that is associated with it (an alternative to buying hydrocortisone cream).^[20]

Personal hygiene

Sodium bicarbonate can be used as an exfoliant. Its particles are rounded and fine in texture, making it both effective and gentle on the skin. Using baking soda as an exfoliating scrub will remove dead skin cells, which can be discolored from hyperpigmentation and scarring.

Sodium bicarbonate is also used as an ingredient in some mouthwashes. It works as a mechanical cleanser on the teeth and gums, neutralizes the production of acid in the mouth and also as an antiseptic to help prevent infections occurring.

A paste made from sodium bicarbonate and a 3% hydrogen peroxide solution can be used as an alternative to commercial non-fluoride toothpastes^{[citation needed]}, and sodium bicarbonate in combination with other ingredients can be used to make a dry or wet deodorant. It may also be used as a shampoo.^[21]

Baking soda in sports

Small amounts of sodium bicarbonate have been shown to be useful as a supplement for athletes in speed-based events, like middle distance running, lasting from about one to seven minutes.^[22][23] But overdose is a serious risk because sodium bicarbonate is slightly toxic^[24] and in particular gastrointestinal irritation is of concern.^[23] Additionally this practice causes a significant increase in dietary sodium.

As a cleaning agent

A paste from baking soda can be very effective when used in cleaning and scrubbing.^[25] For cleaning aluminium objects, the use of sodium bicarbonate is discouraged as it attacks the thin unreactive protective oxide layer of this otherwise very reactive metal. A solution in warm water will remove the tarnish from silver when the silver is in contact with a piece of aluminium foil.^[26][27]

Baking soda is commonly added to washing machines as a replacement for softener and also to remove odors from clothes. Sodium bicarbonate is also effective in removing heavy tea and coffee stains from cups when diluted with warm water.

Cattle feed supplement

Sodium bicarbonate is sold as a cattle feed supplement, in particular as a buffering agent for the rumen.

Miscellaneous

Sodium bicarbonate can be used to extinguish small grease or electrical fires by being thrown over the fire.^[10] However, it should not be applied to fires in deep fryers, as it may cause the grease to splatter.^[10] Sodium bicarbonate is used in BC dry chemical fire extinguishers as an alternative to the more corrosive ammonium phosphate in ABC extinguishers. The alkali nature of sodium bicarbonate makes it the only dry chemical agent, besides Purple-K, 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 effect on hot grease, which forms a smothering soapy foam. Dry chemicals have since fallen out of favor for kitchen fires, as they have no cooling effect compared to the extremely effective wet chemical agents specifically designed for such hazards.^{[citation needed]}

Sodium bicarbonate is used in a process for cleaning paint called sodablasting. It can be administered to pools, spas, and garden ponds to raise pH levels.^[28] It has weak disinfectant properties,^[29][30] and it may be an effective fungicide against some organisms.^[31]

Since it acts as a neutralizing agent, it can be used to absorb odors that are caused by strong acids.^{[citation needed]} It is a tried-and-true method of used-book sellers. The baking soda will absorb the musty smell, leaving the books less malodorous.^[32]

See also

• Carbonic acid
• Baking powder
• List of minerals
• Nahcolite
• Natron
• Natrona (disambiguation)
• Trona

References

1. ^ "Physical Constants of Inorganic Compounds". CRC Handbook, p. 4-85.
2. ^ ^{a b} "Aqueous solubility of inorganic compounds at various temperatures". CRC Handbook, p. 8-116.
3. ^ ^{a b} "Sodium Bicarbonate". UNEP Publications. http://www.chem.unep.ch/irptc/sids/oecdsids/Sodium%20bicarbonate.pdf. 
4. ^ ^{a b} Goldberg, Robert N.; Kishore, Nand; Lennen, Rebecca M.. "Thermodynamic quantities for the ionization reactions of buffers in water". CRC Handbook. pp. 7–13. 
5. ^ "Company History". Church & Dwight Co.. http://www.churchdwight.com/Company/corp_history.asp. 
6. ^ Rudyard Kipling, Captains Courageous  p. 25
7. ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
8. ^ "Decomposition of Carbonates". General Chemistry Online. http://antoine.frostburg.edu/chem/senese/101/inorganic/faq/carbonate-decomposition.shtml. 
9. ^ Radiation Cookery Book 45th Edition, Radiation Group Sales Ltd 1954
10. ^ ^{a b c} "Arm & Hammer Baking Soda – Basics – The Magic Of Arm & Hammer Baking Soda". Armhammer.com. http://www.armhammer.com/basics/magic/#9. Retrieved 2009-07-30. 
11. ^ "White Phosphorus". GlobalSecurity.org. http://www.globalsecurity.org/military/systems/munitions/wp.htm. Retrieved 2007-09-26. 
12. ^ "Outdoor Fun: Pool Care". Arm & Hammer Baking Soda. 2003. http://www.armhammer.com/myfamily/tips/outdoors.asp. Retrieved 2007-09-26. 
13. ^ "Sodium Bicarbonate". Jackson Siegelbaum Gastroenterology. 1998. http://www.gicare.com/pated/sodium_bicarbonate.htm. 
14. ^ List of ingredients – Life Brand Gripe Water
15. ^ "New Scientist Last Word Blog: Soda soother". New Scientist. http://www.newscientist.com/blog/lastword/2008/05/soda-soother.html. Retrieved 22 September 2011. 
16. ^ "Sodium Bicarbonate Intravenous Infusion". Consumer Medicine Information. Better Health Channel. 2004-07-13. http://www.betterhealth.vic.gov.au/bhcv2/bhcmed.nsf/pages/pucsodbi/$File/pucsodbi.pdf. 
17. ^ "Respiratory Acidosis: Treatment & Medication". emedicine. http://emedicine.medscape.com/article/301574-treatment. 
18. ^ Knudsen, K; Abrahamsson, J (Apr 1997). "Epinephrine and sodium bicarbonate independently and additively increase survival in experimental amitriptyline poisoning". Critical care medicine 25 (4): 669–74. doi:10.1097/00003246-199704000-00019. ISSN 0090-3493. PMID 9142034. 
19. ^ "Insect bites and stings: First aid". Mayo Clinic. 2008-01-15. http://www.mayoclinic.com/health/first-aid-insect-bites/fa00046. 
20. ^ What is Sodium Bicarbonate Used For?. Virtuowl.com. Retrieved on 2010-09-24.
21. ^ Bouchard, Mallory (2010-05-04). "A Green and Healthy Beauty Secret: Going Shampoo-Free". Four Green Steps. http://www.fourgreensteps.com/infozone/featured/features/a-green-and-healthy-beauty-secret-going-shampoo-free. 
22. ^ Bee, Peta (2008-08-16). "Is bicarbonate of soda a performance enhancing drug". The Times (London). http://women.timesonline.co.uk/tol/life_and_style/women/body_and_soul/article4539000.ece. Retrieved 2010-05-23. 
23. ^ ^{a b} Ergogenic Aids. U. Retrieved on 2011-09-11.
24. ^ Baking soda overdose – All Information. Umm.edu (2009-10-19). Retrieved on 2010-09-24.
25. ^ "Arm & Hammer Baking Soda – Basics – The Magic Of Arm & Hammer Baking Soda". Armhammer.com. http://www.armhammer.com/basics/magic/#3. Retrieved 2009-07-30. 
26. ^ Eco Silver Polishing. instructables.com (2006-12-20). Retrieved on 2011-10-07.
27. ^ "Put a Shine on It". scifun.chem.wisc.edu. http://scifun.chem.wisc.edu/homeexpts/TARNISH.html. Retrieved 2011-03-06. 
28. ^ "Arm & Hammer Baking Soda – Basics – The Magic Of Arm & Hammer Baking Soda". Armhammer.com. http://www.armhammer.com/basics/magic/#8. Retrieved 2009-07-30. 
29. ^ Malik, Ys; Goyal, Sm (May 2006). "Virucidal efficacy of sodium bicarbonate on a food contact surface against feline calicivirus, a norovirus surrogate". International journal of food microbiology 109 (1–2): 160–3. doi:10.1016/j.ijfoodmicro.2005.08.033. ISSN 0168-1605. PMID 16540196. 
30. ^ William A. Rutala, Susan L. Barbee, Newman C. Aguiar, Mark D. Sobsey, David J. Weber, (2000). "Antimicrobial Activity of Home Disinfectants and Natural Products Against Potential Human Pathogens". Infection Control and Hospital Epidemiology (The University of Chicago Press on behalf of The Society for Healthcare Epidemiology of America) 21 (1): 33–38. doi:10.1086/501694. JSTOR 10.1086/501694. PMID 10656352. 
31. ^ Zamani, M; Sharifi, Tehrani, A; Ali, Abadi, Aa (2007). "Evaluation of antifungal activity of carbonate and bicarbonate salts alone or in combination with biocontrol agents in control of citrus green mold". Communications in agricultural and applied biological sciences 72 (4): 773–7. PMID 18396809. 
32. ^ Gail Altman (2006-05-22). "Book Repair for BookThinkers: How To Remove Odors From Books". The BookThinker (69). http://www.bookthink.com/0069/69alt.htm. 

Further reading

• Bishop, D; Edge, J; Davis, C; Goodman, C (May 2004). "Induced metabolic alkalosis affects muscle metabolism and repeated-sprint ability.". Medicine and science in sports and exercise 36 (5): 807–13. ISSN 0195-9131. PMID 15126714. 
• David R. Lide, ed (2003). CRC Handbook of Chemistry and Physics (84th ed.). Boca Raton, FL: CRC Press. ISBN 0849304849. http://books.google.com/books?id=q2qJId5TKOkC. 

External links

• International Chemical Safety Card 1044
• Differences between Baking Soda and Baking Powder