Sodium bicarbonate

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Sodium bicarbonate
SodiumBicarbonate.png
Ball and stick model of a sodium cation
Ball and stick model of a bicarbonate anion
Sample of sodium bicarbonate
Names
IUPAC name
Sodium hydrogen carbonate
Other names
Baking soda, bicarbonate of soda, nahcolite
Identifiers
144-55-8 YesY
4153970
ChEBI CHEBI:32139 YesY
ChEMBL ChEMBL1353 YesY
ChemSpider 8609 YesY
DrugBank DB01390 YesY
EC Number 205-633-8
4507
Jmol 3D model Interactive image
KEGG C12603 YesY
MeSH Sodium+bicarbonate
PubChem 516892
RTECS number VZ0950000
UNII 8MDF5V39QO YesY
  • InChI=1S/CH2O3.Na/c2-1(3)4;/h(H2,2,3,4);/q;+1/p-1 YesY
    Key: UIIMBOGNXHQVGW-UHFFFAOYSA-M YesY
  • InChI=1/CH2O3.Na/c2-1(3)4;/h(H2,2,3,4);/q;+1/p-1
    Key: UIIMBOGNXHQVGW-REWHXWOFAQ
  • [Na+].OC([O-])=O
Properties
NaHCO
3
Molar mass 84.0066 g mol−1
Appearance White crystals
Odor odorless
Density 2.20 g/cm3[1]
Melting point 50 °C (122 °F; 323 K) (decomposes to sodium carbonate)
9 g/100 mL

69 g/L (0 °C)[2]
96 g/L (20 °C)[3]
165 g/L (60 °C)[3]
236 g/L (100 °C)[2]
Solubility 0.02 %wt acetone, 2.13 %wt methanol @22 °C.[4] insoluble in ethanol
log P -0.82
Acidity (pKa) 10.329[5]

6.351 (carbonic acid)[5]
1.3344
Structure
monoclinic
Thermochemistry
87.61 J/mol K
102 J/mol K
-947.7 kJ/mol
-851.9 kJ/mol
Pharmacology
ATC code B05CB04
B05XA02, QG04BQ01 (WHO)
Intravenous, oral
Vapor pressure {{{value}}}
Related compounds
Other anions
 Sodium carbonate
Other cations
 Ammonium bicarbonate

Potassium bicarbonate
Related compounds
 Sodium bisulfate

Sodium hydrogen phosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY verify (what is YesYN ?)
Infobox references

Sodium bicarbonate[note 1] (IUPAC name: sodium hydrogen carbonate) is a chemical compound with the formula NaHCO3. It is a salt composed of sodium ions and bicarbonate ions. 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 among the food additives encoded by European Union, identified as E 500. 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.[note 2] The word saleratus, from Latin sal æratus meaning "aerated salt", was widely used in the 19th century for both sodium bicarbonate and potassium bicarbonate.

History

The ancient Egyptians used natural deposits of natron, a mixture consisting mostly of sodium carbonate decahydrate, and sodium bicarbonate. The natron was ground up, solvated, and used as paint for hieroglyphics.[citation needed]

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.[6]

This compound, referred to as saleratus, 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.[7]

Production

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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. The product shows a low purity (75%). Pure product is obtained from sodium carbonate, water, and carbon dioxide as reported in one of the following reactions. It is produced on the scale of about 100,000 tonnes/year (as of 2001).[8]

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 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 in situ leach techniques involving dissolution of the nahcolite by heated water pumped through the nahcolite beds and reconstituted through a natural cooling crystallisation 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 → H
2CO
3 + 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 CO
2. This reaction is used to test for the presence of carboxylic groups in protein.[citation needed]

Thermal decomposition

Above 50°C, sodium bicarbonate gradually decomposes into sodium carbonate, water and carbon dioxide. The conversion is fast at 200°C:[9]

2 NaHCO3 → Na2CO3 + H2O + CO2

Most bicarbonates undergo this dehydration reaction. Further heating converts the carbonate into the oxide (at over 850°C):[9]

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

Sodium bicarbonate has a wide variety of uses.

Pest control

Used to kill cockroaches. Once consumed, it causes internal organs of cockroaches to burst due to gas collection.[10]

Paint and corrosion removal

Sodium bicarbonate is used in a process for removing paint and corrosion called sodablasting; the process is particularly suitable for cleaning aluminium panels which can be distorted by other types of abrasive.

pH balancer

It can be administered to pools, spas, and garden ponds to raise pH levels.[11]

Mild disinfectant

It has weak disinfectant properties,[12][13] and it may be an effective fungicide against some organisms.[14] Because baking soda will absorb musty smells, it has become a reliable method for used-book sellers when making books less malodorous.[15]

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.[16] However, it should not be applied to fires in deep fryers; the sudden release of gas may cause the grease to splatter.[16] Sodium bicarbonate is used in BC dry chemical fire extinguishers as an alternative to the more corrosive ammonium phosphate in ABC extinguishers. The alkaline 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.

Cooking

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Main article: Leavening agent

With acids

Sodium bicarbonate, referred to as "baking soda", is primarily used in 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, soda bread, and other baked and fried foods. Acidic compounds that induce this reaction include phosphates, cream of tartar, lemon juice, yogurt, buttermilk, cocoa and vinegar. Natural acids in sourdough can be leavened with the addition of small amounts as well.[17] Sodium bicarbonate can be substituted for baking powder provided sufficient acid reagent is also added to the recipe.[18] Many forms of baking powder contain sodium bicarbonate combined with calcium acid phosphate, sodium aluminium phosphate [19] 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. However, it is still used in Asian and Latin American cuisine to tenderise meats. Baking soda may react with acids in food, including vitamin C (L-ascorbic acid). It is also used in breading such as for fried foods to enhance crispness and allow passages for steam to escape, so the breading is not blown off during cooking.

By heating

Heat causes sodium bicarbonate to act as a raising agent by releasing carbon dioxide when used in baking. The carbon dioxide production starts at temperatures above 80°C. 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.

2NaHCO3 → Na2CO3 + H2O + CO2

Neutralisation of acids and bases

Sodium bicarbonate is amphoteric, reacting with acids and bases. It reacts violently with acids, releasing CO2 gas as a reaction product. However, sodium bicarbonate is not recommended for the clean-up of acid spills. The heat produced increases the reactivity of the acid,[citation needed] and the large amount of carbon dioxide produced may increase the area of the spill.

A wide variety of applications follows from its neutralisation properties, including reducing the spread of white phosphorus from incendiary bullets inside an afflicted soldier's wounds.[20][medical citation needed]

Medical uses

Sodium bicarbonate mixed with water can be used as an antacid to treat acid indigestion and heartburn.[21]

Intravenous sodium bicarbonate is an aqueous solution that is sometimes used for cases of acidosis, or when insufficient sodium or bicarbonate ions are in the blood.[22] 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 markedly (<7.1–7.0) low.[23]

It is used for treatment of hyperkalemia, as it will drive K+ back into cells during periods of hypochloremic metabolic alkalosis.[24] 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.[25] Sodium bicarbonate has also been used in the treatment of tricyclic antidepressant overdose.[26] 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).[27]

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 treat an allergic reaction to plants such as poison ivy, poison oak, or poison sumac to relieve some of the associated itching.[28]

Bicarbonate of soda can also be useful in removing splinters from the skin.[29]

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.[30]

Sodium bicarbonate can be added to local anaesthetics, to speed up the onset of their effects and make their injection less painful.[31] It is also a component of Moffett's solution, used in nasal surgery.

Personal hygiene

Toothpaste containing sodium bicarbonate has in several studies been shown to have a better whitening[32][32][33][34] and plaque removal effect[35][36] than toothpastes without it.

Sodium bicarbonate is also used as an ingredient in some mouthwashes. It has anticaries and abrasive properties.[37] It works as a mechanical cleanser on the teeth and gums, neutralises the production of acid in the mouth, and also acts as an antiseptic to help prevent infections.[38][39]

Sodium bicarbonate in combination with other ingredients can be used to make a dry or wet deodorant.[40][41] It may also be used as a shampoo.[42]

Sodium bicarbonate may be used as a buffering agent, combined with table salt, when creating a solution for nasal irrigation.[43]

It is used in eye hygiene to treat blepharitis. This is done by addition of a tablespoon 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.[44]

In sports

Small amounts of sodium bicarbonate have been shown to be useful as a supplement for athletes in speed-based events, such as middle-distance running, lasting from about one to seven minutes.[45][46] However, overdose is a serious risk because sodium bicarbonate is slightly toxic;[47] and gastrointestinal irritation is of particular concern.[46] 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.[48] 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.[citation needed] A solution in warm water will remove the tarnish from silver when the silver is in contact with a piece of aluminium foil.[49][50] A paste of sodium bicarbonate and water is useful in removing surface rust as the rust forms a water-soluble compound when in a concentrated alkaline solution.[51] Cold water should be used, as hot water solutions can corrode steel.[52]

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

During the Manhattan Project to develop the atomic bomb in the early 1940s, many scientists investigated the toxic properties of uranium. They found that uranium oxides stick very well to cotton cloth, but did not wash out with soap or laundry detergent. The uranium would wash out with a 2% solution of sodium bicarbonate (baking soda). Clothing can become contaminated with depleted uranium (DU) dust, and then normal laundering will not remove it. Those at risk of DU dust exposure should have their clothing washed with about 6 ounces (170 g) of baking soda in 2 gallons (7.5 l) of water).[53]

As a biopesticide

Sodium bicarbonate can be an effective way of controlling fungal growth,[54] and in the United States is registered by the Environmental Protection Agency as a biopesticide.[55]

Cattle feed supplements

Sodium bicarbonate is sold as a cattle feed supplement, in particular as a buffering agent for the rumen.[56]

In popular culture

Film

Sodium bicarbonate, as 'bicarbonate of soda', was a frequent source of punch lines for Groucho Marx in Marx brothers movies. In 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."[57] In 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."[58]

Difference between baking soda and baking powder

Quite simply, baking powder contains baking soda, as well as a powdered acid and cornstarch. In scientific terms, baking soda is a pure substance; baking powder is a mixture.

Baking soda is alkaline, so acid is used in baking powder to avoid a metallic taste when the chemical change during baking creates sodium carbonate. However, to avoid the over-flavouring of acidic taste, non-acid ingredients such as whole milk or Dutch-processed cocoa must be added.[59]

See also

Notes

  1. ↑ The prefix "bi" in "bicarbonate" comes from an outdated naming system and is based on the observation that there is two times as much carbonate (CO3) in sodium bicarbonate (NaHCO3) and other bicarbonates as in sodium carbonate (Na2CO3) and other carbonates.
  2. ↑ In colloquial usage, the names sodium bicarbonate and bicarbonate of soda are often truncated. Forms such as sodium bicarb, bicarb soda, bicarbonate, bicarb, or even bica are common.

References

  1. ↑ "Physical Constants of Inorganic Compounds". CRC Handbook, p. 4-85.
  2. ↑ 2.0 2.1 "Aqueous solubility of inorganic compounds at various temperatures". CRC Handbook, p. 8-116.
  3. ↑ 3.0 3.1 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ 5.0 5.1 Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ Lua error in package.lua at line 80: module 'strict' not found. p. 25
  8. ↑ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
  9. ↑ 9.0 9.1 Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  15. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  16. ↑ 16.0 16.1 Lua error in package.lua at line 80: module 'strict' not found.
  17. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  18. ↑ Radiation Cookery Book 45th Edition, Radiation Group Sales Ltd 1954
  19. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  20. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  21. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  22. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  23. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  24. ↑ Medical Toxicology, Richard C. Dart.
  25. ↑ Cloth Diapers, Leah Leverich Ph.D.
  26. ↑ [old info]Lua error in package.lua at line 80: module 'strict' not found.
  27. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  28. ↑ [unreliable medical source?]What is Sodium Bicarbonate Used For?. Virtuowl.com. Retrieved on 2010-09-24.
  29. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  30. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  31. ↑ http://www.frca.co.uk/article.aspx?articleid=100505
  32. ↑ 32.0 32.1 Lua error in package.lua at line 80: module 'strict' not found.
  33. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  34. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  35. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  36. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  37. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  38. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  39. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  40. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  41. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  42. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  43. ↑ Ralph B. Metson, M.D., The Harvard Medical School Guide to Healing Your Sinues (McGraw Hill 2005), at p. 68.
  44. ↑ {cite web|author= Mary Harding, MRCGP|title= Blepharitis|url=http://www.patient.co.uk/health/blepharitis-leaflet
  45. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  46. ↑ 46.0 46.1 Ergogenic Aids. U. Retrieved on 2011-09-11.
  47. ↑ Baking soda overdose – All Information. Umm.edu (2009-10-19). Retrieved on 2010-09-24.
  48. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  49. ↑ Eco Silver Polishing. instructables.com (2006-12-20). Retrieved on 2011-10-07.
  50. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  51. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  52. ↑ .http://www.sciencelab.com/msds.php?msdsId=9927263
  53. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  54. ↑ Potassium bicarbonate (073508) and Sodium bicarbonate (073505) Fact Sheet United States Environmental Protection Agency. Updated 17 February 2011. Retrieved 25 November 2011.
  55. ↑ Registered Biopesticides 04/29/02 United States Environmental Protection Agency. Updated 29 March 2002. Retrieved 25 November 2011.
  56. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  57. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  58. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  59. ↑ Lua error in package.lua at line 80: module 'strict' not found.

Further reading

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External links

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