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Sodium bicarbonate
Sodium bicarbonate
General
Systematic name	sodium hydrogencarbonate
Other names	Sodium bicarbonate Bicarbonate of soda Baking soda
Molecular formula	NaHCO3
Molecular mass	84.007 g/mol
Exact Mass	83.982
Appearance	White crystalline solid.
CAS number
Properties
Density and phase	2.159 g/cm³, solid.
Solubility in water	7.8g/100ml water @ 18C (64F)
Other solvents e.g. ethanol	"slightly"
Melting point	Decomposes below MP
Boiling point	Unknown > Decomposes
Acidity (p''K''a)	6.3
Structure
Molecular shape	?
Coordination geometry	?
Crystal structure	?
Hazards
MSDS	External MSDS
Main hazards	Irritant, esp. to respiratory system
NFPA 704
Flash point	Non-flammable.
R/S statement	R: ? S: ?
RTECS number	VZ0950000
Supplementary data page
Structure and properties	''n'' = 1.500
Thermodynamic data	Phase behaviour Solid
Spectral data	UV, IR, NMR, MS
Related compounds
Other anions	Sodium carbonate, carbonic acid
Other cations	?
Related compounds	Sodium hydrogen sulphate sodium hydrogen phosphate
Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa)

'Sodium bicarbonate' is the chemical compound with the formula NaHCO₃. Because it has long been known and is widely used, the salt has many other names including 'sodium hydrogencarbonate', 'sodium bicarb', 'baking soda', 'bread soda', 'cooking soda', 'bicarb soda', 'saleratus' or 'bicarbonate of soda'. It is soluble in water. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slight alkaline taste resembling that of sodium carbonate. It is a component of the mineral natron and is found dissolved in many mineral springs. The natural mineral form is known as 'nahcolite'. It is also produced artificially.

Contents

Production

Chemistry

Acid-base reactions

Reaction of sodium hydroxide with carbon dioxide

Decomposition

Thermal decomposition

History

Applications

Cooking

For neutralization of acids

Miscellaneous and domestic uses

Safety

References

Further reading

See also

External links

Production

Main articles: Solvay process

NaHCO₃ is mainly prepared by the Solvay process, which entails the reaction of sodium chloride, ammonia, and carbon dioxide in water. It is produced on the scale of about 100,000 ton/year (year: 2001).^[1]
Commercial quantities of baking soda are also produced by this 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

Chemistry

Acid-base reactions

NaHCO₃ is a salt which consists of the ions Na⁺ and the bicarbonate anion, HCO₃^-. It has a pK_a of 6.3 in water which causes aqueous solutions to be mildly alkaline:
:HCO₃^- + H₂O ⇋ H₂CO₃ + OH^-

Reaction of sodium hydroxide with carbon dioxide

NaHCO₃ may be obtained by the reaction of carbon dioxide with an aqueous solution of sodium hydroxide :
The initial reaction produces sodium carbonate:
:CO₂ + 2NaOH → Na₂CO₃ + H₂O
Further addition of carbon dioxide produces sodium bicarbonate, which at sufficiently high concentration will precipitate out of solution:
:Na₂CO₃ + CO₂ + H₂O → 2NaHCO₃

Decomposition

Treatment of sodium bicarbonate with acids, releases carbon dioxide and water:
: NaHCO₃ + HCl → NaCl + H₂O + CO₂ (gas)
: NaHCO₃ + CH₃COOH → CH₃CO₂Na + H₂O + CO₂ (gas)

Thermal decomposition

Above 60 °C, it gradually decomposes into sodium carbonate, water and carbon dioxide. The conversion is fast at 200 °C:
: 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂
Most bicarbonates und-

History

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.

Applications

Cooking

Main articles: leavening agent

Sodium bicarbonate is primarily used in cooking (baking) where it reacts with other components to release carbon dioxide, that helps dough "rise." The acidic compounds that induce this reaction include cream of tartar, lemon juice, yogurt, etc. Some forms of baking powder contain sodium bicarbonate combined with cream of tartar.

★ A small amount can be added to a beef stew to make tough meat tenderize faster.

★ Was formerly used as a source of carbon dioxide for soda water.

★ Can be used when preparing tomato sauce to neutralize the tomato's acidity.

★ It is added to beans in water to prevent flatulence produced by digesting them.

★ It is effective in extinguishing grease fires which may occur when deep frying.

★ In Thailand, soaking insects in baking soda for three to five hours prior to cooking produces a sweeter, more mushroom-like taste in the finished cuisine.

For neutralization of acids

The reaction of acids with sodium bicarbonate is a common method for neutralizing acid spills. The advantage to this method is that one can use excess sodium carbonate, which is relatively innocuous. The neutralization process is signaled by the release of gaseous CO₂. A wide variety of applications follow from its neutralization properties including ameliorating the effects of white phosphorus in incendiary bullets, from spreading inside a soldier's afflicted wounds. Military Application

★ It is commonly used to increase the pH and total alkalinity of the water for pools and spas. Sodium bicarbonate can be added as a simple solution for restoring the pH balance of water that has a high level of chlorine.

★ It is sometimes used in septic tanks to control pH and bacteria.

★ It neutralizes acids, i.e. sulfuric acid (H₂SO₄):
:2 NaHCO₃ + H₂SO₄ ––> Na₂SO₄ + 2 H₂O + 2 CO₂

Miscellaneous and domestic uses

Baking soda has many uses. [1]
'As a deodorizer'

★ An absorbent for moisture and odors e.g; an open box can be left in a refrigerator for this purpose. However, according to one source, baking soda does not actually absorb odors well when used in a refrigerator.

★ To help relieve itching due to bacterial infections
'Medical uses'

★ It is used as an antacid to treat acid indigestion and heartburn.

★ Mixed with water and drunk, it can relieve cystitis.

★ Mixed with water in a 10% solution can soften earwax for removal.

★ In paramedicine, sodium bicarbonate 7.9% is administered intravenously for cases of acidosis and overdoses of acidic toxic substances, such as tricyclic antidepressants and aspirin.

★ Adverse reactions to emergency administration include congestive heart failure, with edema secondary to sodium overload, and the metabolic complication of hyperosmolarity, metabolic acidosis, and hypernatremia.

★ Aids in itch relief from poison ivy rashes.

★ Added to a bath or made into a paste it can be used to relieve the itching caused by chicken pox.

★ For local injections of anesthetics subdermally or subcutaneously, it may be added to lessen the burning sensation of the anesthetic to the patient. For example. 9 milliliters of lidocaine mixed with 1 milliliter of sodium bicarb in a 10 cc syringe will greatly lessen the feeling of burning, pressure and overall pain from the injection.

★ Relieves mosquito bites and bee stings (but not wasp stings).
'Cosmetic uses'

★ It is marketed as a whitener because of its abrasive properties in some toothpaste brands.
'As a cleaning agent'

★ A paste from baking soda can be very effective when used in cleaning and scrubbing.

★ A solution in warm water will remove the tarnish from silver when the silver is in contact with a piece of aluminum foil[2].

★ With water, it cleans the impurities on contact lenses. Rinse completely before wearing contacts to avoid stinging residue.

★ Cleans brushes and combs to prevent residues.

★ Use to clean juice, wine, and coffee stains.

★ Pouring 1 cup of baking soda down a drain and following with 1/2 gallon of vinegar will degrease the drain.
'Other uses'

★ It is used as a fabric softener in laundry.

★ It is used to test garden soil for acidity. If it bubbles, the soil is too acidic.

★ Sodium bicarbonate has been used as a performance enhancer for sprinters, by countering build up of lactate through induced metabolic alkalosis.

★ If mixed with super glue, it makes a suitable filling for cracks in walls.

★ Baking soda can be used as a low-cost alternative to raise pH in swimming pools.[3]

★ Combined with cocaine to make crack cocaine.

★ As a desiccant, sprinkle on wet pages of books and then put them out to dry under the sun.

★ Sodium bicarbonate is used in BC Dry Chemical fire extinguishers as an alternative to the corrosive ammonium phosphate in ABC extinguishers. The alkali nature of Sodium Bicarbonate makes it the only dry powder, excluding Purple-K, agent allowed for use on commercial deep fat fryers, the agent forms a crust over the surface similar to the effects of a wet chemical.

★ Sodium bicarbonate is often used in the pharmaceutical industry as an additive to cell culture media. It acts as a weak buffer.

Safety

Sodium bicarbonate is considered to be relatively safe, however consumption of large amounts should be avoided. See MSDS.

References

1. Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.

Further reading

# Bishop, D., J. Edge, C. Davis, and C. Goodman. Induced Metabolic Alkalosis Affects Muscle Metabolism and Muscle Metabolism and Repeated-Sprint Ability. Medicine and Science in Sports Exercise, Vol. 36, No. 5, pp. 807-813, 2004.

See also

★ Baking powder

★ Natron

★ List of minerals

★ Sodium carbonate

★ Carbonic acid

External links

★ Material Safety Data Sheet

★ Free to read Baking Soda Book

★ How Baking Soda Works (howstuffworks.com)