Generally, elemental salt is more reactive than lithium, and also it reacts with water to type a solid base, salt hydroxide (NaOH). That is chemistry is well explored.

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Reaction with air, water, and hydrogen

Sodium is ordinarily rather reactive with air, and also the reactivity is a role of the loved one humidity, or water-vapour content of the air. The corrosion the solid sodium by oxygen also is sped up by the existence of tiny amounts the impurities in the sodium. In plain air, sodium metal reacts to form a sodium hydroxide film, which can rapidly absorb carbon dioxide native the air, creating sodium bicarbonate. Salt does no react through nitrogen, so salt is usually preserved immersed in a nitrogen atmosphere (or in inert liquids such as kerosene or naphtha). That is significantly more reactive in air as a liquid 보다 as a solid, and the liquid deserve to ignite at around 125 °C (257 °F). In a comparatively dried atmosphere, sodium burns quietly, offering off a thick white caustic smoke, i m sorry can reason choking and also coughing. The temperature of burn sodium boosts rapidly to more than 800 °C (1,500 °F), and under these problems the fire is extremely difficult to extinguish. Special dry-powder fire extinguishers are required, due to the fact that sodium reacts through carbon dioxide, a common propellant in continual fire extinguishers.

Sodium monoxide (Na2O) is ordinarily formed upon oxidation of sodium in dry air. The superoxide (NaO2) can be prepared by heater metallic salt to 300 °C (570 °F) in an autoclave (a heated pressure vessel) include oxygen in ~ high pressure. One more route come the superoxide is oxidation of salt peroxide, Na2O2, treated to have a huge surface area.

Sodium the is heavily contaminated v the monoxide may be readily purified through filtration, because the solubility of the oxide in molten sodium is low. This low solubility is used to a significant extent in continuous purification processes of the salt in huge liquid-metal reactor systems. A second method for removed the oxide, dubbed cold trapping, entails running the molten sodium through a cooled pack bed that material, top top which the oxide deserve to precipitate. Filtration and also cold trapping also are efficient in removal of gross amounts of carbonate, hydroxide, and also hydride.

The reaction with water of fluid sodium having actually a high surface area deserve to be explosive. The sodium-water reaction is highly exothermic (that is, warmth is given off):


Tests have actually indicated, however, that sodium and water can not be combined fast enough to create the shock tide characteristic that high explosives. The explosive risks of the reaction are associated primarily v the hydrogen gas that is formed.

Pure sodium begins to absorb hydrogen appreciably at around 100 °C (212 °F); the rate of absorption increases with temperature. Pure salt hydride deserve to be formed at temperatures above 350 °C (660 °F) by exposing sodium to hydrogen gas at a high flow rate. At higher temperatures the dissociation of sodium hydride to create hydrogen and molten sodium is substantially greater 보다 that of lithium hydride but slightly much less than that of potassium hydride.

Reaction with nonmetals

Generally, alkali steels react through halogen gases, the level of reactivity decreasing with boosting atomic load of the halogen. Salt is no exemption to this statement. Under specific conditions of reaction, sodium and also halogen vapours react to create light (chemiluminescence). Halogen acids, such as hydrochloric acid, reaction vigorously through sodium, yielding the salt halides. The reaction are highly exothermic, through heats of reaction (energy offered off) that −71.8 and also −76.2 kcal, respectively, because that the reactions through hydrofluoric and hydrochloric acids. Sodium is struck by other strong mineral acids to type the corresponding salts. That reacts through the fumes of nitric acid at 15 °C (59 °F) to kind sodium nitrate and with acetic and also sulfuric mountain to type sodium acetate and also sodium sulfate. V molten sulfur the reacts violently to produce polysulfides; under an ext controlled conditions it reacts through organic remedies of sulfur. Liquid selenium and tellurium both react vigorously v solid salt to type selenides and tellurides.

Sodium shows relatively little reactivity with carbon, return lamellar (layerlike) materials can be prepared in which salt is present between graphite layers. At 625 °C (1,157 °F) carbon monoxide reacts v sodium to kind sodium carbide and also sodium carbonate.

With the exemption of the oxides the the group 4 (IVb) metals (titanium, zirconium, and also hafnium), the oxides that the transition metals are all decreased to the respective metals with elemental sodium. Sodium additionally reacts with a big number the metallic halides, displacing the metal from the salt and also forming a salt halide in the process. This reaction is used in the ready of several of the transition metals themselves, including titanium and also tantalum.

Sodium and also all the various other alkali metals dissolve in fluid ammonia to offer intense blue solutions, and also at plain temperatures a sluggish reaction in between sodium and ammonia wake up to form sodamide, NaNH2, and hydrogen, comparable to the reaction of sodium with water to offer NaOH and also hydrogen. The reaction are

Na + NH3 → NaNH2+ 1/2 H2

Na + H2O → NaOH + 1/2 H2

The reaction that alkali metal-ammonia solutions to kind the amide and hydrogen can be catalyzed by the addition of many metals and also metal oxides.

Liquid ammonia is frequently used together a solvent because that sodium, permitting a number of reactions to happen at simple temperatures that would otherwise need heat. Sodium superoxide (NaO2), because that example, deserve to be created by pass oxygen v ammonia options of salt at −77 °C (−107 °F). Ammonia also serves as a solvent because that reactions of sodium with arsenic, tellurium, antimony, bismuth, and a number of other low-melting metals. Sodium-ammonia services are used to blacken polytetrafluoroethylene (Teflon) to prepare its surface for cementing to other materials. The high reducing power of sodium-ammonia solutions provides them helpful in a variety of organic reactions well-known as Birch reductions.

Organic reactions

The organic reaction of sodium have been learned to a greater level than those of any of the other alkali metals. Salt reacts with anhydrous alcohols to kind the particular alcoholates (or alkoxides) according to

Na + ROH → RONa + 1/2 H2,

in i m sorry R is the organic section of the alcohol (R = CH3 for methanol, CH3CH2 because that ethanol, etc.). The reaction is many vigorous with methanol and decreases with increasing molecular weight of the alcohol. Salt methoxide is developed on an commercial scale by reaction that sodium with excess methanol. Organic acids react v sodium to type sodium salts.

The huge negative free energy of development of sodium halides patent the dehalogenation of a variety of organic halides, the development of the sodium halide gift energetically favoured. The so-called Wurtz reaction—based on this principle—is supplied in organic synthetic to a substantial extent:

2RCl + 2Na → R―R + 2NaCl.

By this reaction, octane can be made from bromobutane and also sodium. Organosodium compounds incorporate a number in which the sodium atom is bonded directly to a carbon atom; an example is methylsodium, Na―CH3. Together compounds deserve to be prepared by the action of sodium on mercury dialkyls or diaryls, as in the following equation:

Hg(CH3)2 + 2Na → 2NaCH3 + Hg.

Sodium reaction violently through a number of halogenated hydrocarbons. Because that example, a violent to explode occurs as soon as a mixture of carbon tetrachloride and also sodium is subjected to shock. Also when the salt is diluted come a substantial extent—as in sodium amalgam—a brisk reaction v carbon tetrachloride occurs.

Reaction with metals

Sodium is fully miscible v the alkali metals below it in the periodic table (potassium, rubidium, and cesium). A eutectic (that is, one alloy that melts lower than that components) melting at −10 °C (14 °F) is created in the sodium-potassium system and is well-known commercially as NaK. Its composition is approximately 78 percent potassium, and also it is supplied as a heat-transfer fluid and also as an organic reactant. The eutectics created in the sodium-rubidium and sodium-cesium binary equipment melt, respectively, in ~ −4.5 and −30 °C (24 and −22 °F). Salt is the boy component through potassium and also cesium the the ternary alloy NaKCs, melting at −78 °C (−108 °F). This liquid is the lowest-melting fluid alloy yet isolated.

Sodium also forms alloys through the alkaline-earth metals. Beryllium is dissolve in sodium only to the extent of a few atomic percent at around 800 °C (1,500 °F). Fluid sodium and magnesium are just partially miscible. The degree of solubility in sodium of the alkaline-earth metals boosts with raising atomic weight, through the result that the solubility of calcium is 10 percent by load at 700 °C (1,300 °F). In the sodium-strontium system, there is a considerable degree of miscibility. Sodium forms a number of compounds with barium, and also several eutectics exist in the system.

The precious metals, such as silver, gold, platinum, palladium, and also iridium, and also the white metals, such as lead, tin, bismuth, and also antimony, alloy come an appreciable extent with liquid sodium. Cadmium and also mercury also react through sodium, and also a variety of compounds exist in both binary systems. 7 sodium-mercury compounds, or amalgams, exist, with Hg2Na having actually the highest melting allude (354 °C, or 669 °F). Salt amalgams are offered chiefly for carrying out reaction in situations in i beg your pardon pure element sodium would certainly be violently reactive and challenging to control. The solubility of change metals in alkali metals is generally an extremely low, often in the 1–10-parts every million range even at temperature in overabundance of 500 °C (930 °F).

Nuclear properties

Natural salt is the secure isotope of mass 23. The the radioactive synthetic isotopes, sodium-22 (2.6-year half-life, the longest half-life the a sodium isotope) is supplied as a radiation tracer for natural sodium. Sodium-24 (15-hour half-life) is minimal in use by its short life and is developed by irradiation in a nuclear reactor. Therefore reaction, a sodium-cooled reactor must have a second heat-transfer loop so that radioactive salt does not come in call with the environment. Other isotopes have half-lives the a minute or less.

Biological properties

Sodium salts, particularly sodium chloride, are found virtually everywhere in biological material. Sodium is an important element because that life, as is potassium, and also the two aspects maintain a definite balance within the cell structure. Electrolyte balance in between the inside of the cell and also the outside is maintained by “active transport” that potassium ions right into the cell and also sodium ions out of the cell. Many of the biological effects of sodium salts space the result of the cation (Na+), with the an adverse counter-ion supposedly not playing a leading role.

The existence of salinity in soils is regularly detrimental to plant growth. Salt ions change calcium and other ions in clay complexes, transforming the clay come a difficult mass; water percolation is then drastically reduced, and the basicity the the soil rises markedly.

The tolerance of fish to alters in salinity is often quite remarkable. Numerous marine bacteria and diatoms room able to tolerate salt concentrations as good as 25 percent. The minimum sodium necessity for mammals shows up to it is in 0.05 percent the the diet, equivalent in a typical adult come a requirement of 1–2 grams (0.04–0.07 ounce) of salt every day, which results in an mean sodium contents of body tissues of 0.24 percent. There is a broad variation of sodium content in the different tissues, with totality blood containing about 0.62 percent salt chloride, whereas skin has a salt content of much less than 0.1 percent. There is a relationship in between salt content and also water balance of the body; a short salt intake causes loss that water. Significant quantities of sodium are shed through the skin by perspiration, and also considerable quantities can be excreted in the urine.

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This short article was many recently revised and also updated by Melissa Petruzzello, associate Editor.