Sodium hydrogen carbonate

Structural formula
General
Surname Sodium hydrogen carbonate
other names
• Sodium hydrogen carbonate
• Baking soda
• Emperor soda
• bicarbonate of soda
• Sodium bicarbonate
• Sodium bicarbonate
• Baking soda
• Bullrich Salt
• E  500 (ii)
• SODIUM BICARBONATE ( INCI )
Molecular formula NaHCO 3
Brief description

colorless, odorless, crystalline solid

External identifiers / databases
 CAS number 144-55-8 EC number 205-633-8 ECHA InfoCard 100.005.122 PubChem 516892 ChemSpider 8609 DrugBank DB01390 Wikidata Q179731
properties
Molar mass 84.01 g mol −1
Physical state

firmly

density

2.22 g cm −3 (20 ° C)

Melting point

Decomposition from 270 ° C

pK s value
solubility

moderate in water (96 g l −1 at 20 ° C)

safety instructions
GHS labeling of hazardous substances
 no GHS pictograms
H and P phrases H: no H-phrases
P: no P-phrases
Toxicological data

4220 mg kg −1 ( LD 50ratoral )

Thermodynamic properties
ΔH f 0

−950.8 kJ / mol

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Sodium hydrogen carbonate (common name : soda ) has the empirical formula NaHCO 3 , is a sodium salt of carbonic acid and is one of the hydrogen carbonates . The compound should not be confused with sodium carbonate (soda, empirical formula Na 2 CO 3 ). Occasionally, the outdated and chemically incorrect trivial names bicarbonate of soda and sodium bicarbonate (also NaBi for short ) are used for sodium hydrogen carbonate . In trade, the connection is also under the names baking soda , baking soda , baking soda , baking soda offered and brand names.

etymology

The word Natron has existed in German since the beginning of modern times (in the forms anatron , natrum and natron ) and originated (like Spanish, French and English natron and " sodium ") from Arabic naṭrūn (or anatrūn ; cf. the Lower Egyptian "Natrontal") "Wadi an-Natrūn" , from which a mixture of sodium carbonate and sodium hydrogen carbonate was used to draw water from mummies) 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 German salniter (from which nitrogen , nitrate , etc. can then be derived).

Almost a century ago, in the dictionary of the Egyptian language by Adolf Erman and Hermann Grapow , Greek nítron (νίτρον) and Hebrew neter / nether were linked with the ancient Egyptian word nṯr.j , which was pronounced / natsₑra- / in the 2nd millennium BC . Since the Natron word was found in many unrelated but neighboring languages ​​during this period, this etymology must be considered probable.

Ancient Egyptian nṯr.j does not mean “divine” in relation to baking soda and does not refer to baking soda as a divine substance, as is often read. All objects and substances used to prepare a corpse for burial and mummification are generally called nṯr.j , for example mummy bandages and mummification devices , i.e. “ items belonging to the burial”.

Occurrence

Sodium hydrogen carbonate occurs as a natural mineral Nahcolith in the United States among others. It usually occurs finely divided in oil shale and can then only be obtained as a by-product of oil production. Particularly rich Nahcolith horizons are mined in the state of Colorado ; the annual production in 2007 was 93,440 tons. There are also localities in Europe.

presentation

Reaction of saturated sodium carbonate solution with carbon dioxide with cooling:

${\ displaystyle \ mathrm {Na_ {2} CO_ {3} + CO_ {2} + H_ {2} O \ longrightarrow 2 \ NaHCO_ {3} \ downarrow}}$

This is an equilibrium reaction, but it is strongly shifted to the right due to the relatively poor solubility of sodium hydrogen carbonate. The filtered sodium hydrogen carbonate must be carefully dried so that it does not decompose again (in reverse of the formation reaction).

In this way it was presented for the first time by the pharmacist Valentin Rose the Younger in Berlin in 1801.

In the Solvay process precipitating sodium hydrogen carbonate as an intermediate product (mainly due to the co-precipitated impurities ammonium chloride ) are not normally used.

properties

Sodium hydrogen carbonate is a colorless, crystalline solid that decomposes above a temperature of 50 ° C with elimination of water and carbon dioxide to form sodium carbonate.

${\ displaystyle \ mathrm {2 \ NaHCO_ {3} \ longrightarrow Na_ {2} CO_ {3} + CO_ {2} + H_ {2} O}}$

In contrast to sodium carbonate , it dissolves in water with only a weakly alkaline reaction.

${\ displaystyle \ mathrm {HCO_ {3} ^ {\, -} + H_ {2} O \ leftrightharpoons H_ {2} O + CO_ {2} + OH ^ {-}}}$

Sodium hydrogen carbonate has a monoclinic crystal structure with the space group P 2 1 / c (space group no. 14) and the lattice parameters a = 3.51  Å , b = 9.71 Å, c = 8.05 Å and β = 111 ° 51 ′ . The compound forms mixed crystals with sodium carbonate.

use

Sodium hydrogen carbonate is mainly used to make baking soda and effervescent powder. The global production volume is in the 100,000 ton range.

The connection has a wide range of uses in general:

• In food technology
• In sports nutrition
• When used and dosed appropriately in healthy, trained and not malnourished people, a positive effect on endurance can be either proven or likely.
• In the medicine
• for brushing teeth (soda or baking soda is contained in many toothpastes , especially in countries like the USA), but not because of an often - but incorrectly - assumed abrasive effect
• in professional tooth cleaning (PZR) in prophylaxis (dentistry)
• as a heartburn remedy because of the neutralization effect with the formation of non-toxic reaction products (CO 2 and water); is now considered out of date (see antacid , proton pump inhibitor ). NaHCO 3 is still contained in many products for heartburn and acid-related stomach problems. For example, Bullrich Salt consists of 100% sodium hydrogen carbonate.
• as an antidote for poisoning by barbiturates , salicylates and tricyclic antidepressants
• as part of a drinking solution (together with potassium chloride , sodium chloride and macrogol ) for colon cleansing as preparation for a colonoscopy (colonoscopy).
• as a buffer substance to compensate for the base deficit during hemodialysis (acidosis correction). In the so-called bicarbonate dialysis , sodium hydrogen carbonate is probably the most important component of the dialysate. In contrast to acetate or lactate, NaHCO 3 does not have to be metabolized in order to be effective. Because of its benefits for the cardiovascular system, it is the most frequently used buffer substance in hemodialysis worldwide. In addition, this procedure is less likely to cause drops in blood pressure, nausea, and cramps.
• for the treatment of metabolic acidosis and hyperkalemia
• In aviation technology
• for heat absorption and for creating a fire-retardant atmosphere in flight recorders
• In environmental technology
• As a sorbent for acidic exhaust gas components (SO x , HCl) in flue gas cleaning systems (Bicar process)
• History of the dehydration of corpses ( mummification )
• In agriculture
• as a remedy against fungal diseases such as powdery mildew and gray rot , known under the name Steinhauer's powdery mildew fright
• as a pH value buffer in dairy cattle feeding
• as a cheese ripening agent (pH blunting, in sour milk cheese dairy) and to delay the coagulation of milk
• As a component of fire extinguishing powders (release of CO 2 when heated)
• For stretching synthetic drugs like amphetamines and for making crack from cocaine
• In the household
• as a component of mild detergents
• as a cleaning agent to remove encrusted food residues. The effect is partly due to the saponification of fatty food residues
• A pinch of baking soda in the cooking water softens peas, lentils and beans faster and removes the bloating effect of various types of cabbage.
• As an addition to the finished cheese fondue , it makes it easier to digest and airy.
• It neutralizes odors: bad breath, drainage pipes, musty shoes, refrigerator, litter box, cages for small animals.
• As a remedy against ants and cockroaches: If you sprinkle baking soda in the holes of the ant burrow and on the ant paths, the ants pick up the baking soda and carry it into their burrow. Baking soda changes the pH in the ants' body, which leads to death.
• Excess acid in food is neutralized or weakened by baking soda. This is important when preparing jams from sour fruits such as sea ​​buckthorn or rhubarb , as this gives them a milder taste and less sugar has to be used. Vinegar or lemon juice that is excessively added to a meal can also be neutralized by baking soda.
• In the aquarium hobby and in pool water
• to increase the buffer capacity to prevent an acid fall
• to regulate the KH value , e.g. B. in saltwater aquariums , or to regulate the alkalinity in swimming pools (so-called Alka-Plus products consist of sodium hydrogen carbonate)
• In toy rockets , it is used together with vinegar or citric acid as fuel (through the formation of the gas carbon dioxide)
• In the laboratory to neutralize spilled acids, mostly as a 5% solution.
• As a non-abrasive blasting agent in blasting technology , see soda blasting .

Biological importance

It reacts with acids in a foaming manner, forming carbon dioxide and water.

${\ displaystyle \ mathrm {NaHCO_ {3 (aq)} + HCl _ {(aq)} \ longrightarrow NaCl _ {(aq)} + CO_ {2 (g)} + H_ {2} O}}$
Sodium hydrogen carbonate and hydrochloric acid react to form sodium chloride , carbon dioxide and water.

The ability to neutralize acids with HCO 3 - is vital for the body.

• In the stomach due to the active there must enzymes an acidic environment rule, this is done by production of hydrogen chloride (HCl) to give together with water of gastric juice (about 0.5 percent hydrochloric acid) forms, their pH (fasted) to can drop to 1–1.5. The epithelial cells of the stomach wall, which would perish immediately at such a low pH value, protect themselves by releasing mucus mixed with HCO 3 - . If H + ions in the hydrochloric acid penetrate the mucous layer, they are neutralized to form CO 2 and water. The CO 2 mostly escapes through the esophagus.
• In turn, an alkaline environment is required in the small intestine , as other enzymes take over the cleavage of the nutrients. The change of the pH value takes place in the duodenum ( the duodenum ) by feeding the secretion of the pancreas , which among other things also - as the output in the stomach mucus - HCO 3 - contains.
• Hydrogen carbonate HCO 3 - is the most important blood buffer for regulating the acid-base balance in humans.

Commons : Sodium Hydrogen Carbonate  - Collection of pictures, videos and audio files
Wiktionary: Sodium hydrogen carbonate  - explanations of meanings, word origins, synonyms, translations

Individual evidence

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