Chemical Fact Sheet
Sodium
| Chemical Abstract Number (CAS #) | 7440-23-5 |
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| Synonyms | Natrium; Sodium-(Liquidalloy); Sodium-metal; Sodium-23; Sodio-(Spanish) |
| Analytical Methods | 200.7 - 6010 |
| Molecular Formula | Na |
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Synopsis
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Sodium - (English, soda; Medieval Latin, sodanum, headache remedy), Na (L. natrium); at. wt. 22.989768(6); at. no. 11; m.p. 97.72 +/- 0.03 deg C; b.p. 883 deg C; sp. gr. 0.971 (20 deg C); valence 1. Long recognized in compounds, sodium was first isolated by Davy in 1807 by electrolysis of caustic soda. Sodium is present in fair abundance in the sun and stars. The D lines of sodium are among the most prominent in the solar spectrum. Sodium is the sixth most abundant element on earth, comprising about 2.6% of the earth's crust; it is the most abundant of the alkali group of metals of which it is a member. The most common compound is sodium chloride, but it occurs in many other minerals, such as soda niter, cryolite, amphibole, zeolite, sodalite, etc. It is a very reactive element and is never found free in nature. It is now obtained commercially by the electrolysis of absolutely dry fused sodium chloride. This method is much cheaper than that of electrolyzing sodium hydroxide, as was used several years ago. Sodium is a soft, bright, silvery metal which floats on water, decomposing it with the evolution of hydrogen and the formation of the hydroxide. It may or may not ignite spontaneously on water, depending on the amount of oxide and metal exposed to the water. It normally does not ignite in air at temperatures below 115 deg C. Sodium should be handled with respect, as it can be dangerous when improperly handled. Metallic sodium is vital in the manufacture of sodamide and esters, and in the preparation of organic compounds. The metal may be used to improve the structure of certain alloys, to descale metal, to purify molten metals, and as a heat transfer agent. An alloy of sodium with potassium, NaK, is also an important heat transfer agent. Sodium compounds are important to the paper, glass, soap, textile, petroleum, chemical, and metal industries. Soap is generally a sodium salt of certain fatty acids. The importance of common salt to animal nutrition has been recognized since prehistoric times. Among the many compounds that are of the greatest industrial importance are common salt (NaCl), soda ash (Na2CO3), baking soda (NaHCO3), caustic soda (NaOH), Chile saltpeter (NaNO3), di- and tri-sodium phosphates, sodium thiosulfate (hypo, Na2S2O3 - 5H2O), and borax (Na2B4O7 - 10H2O)- Seventeen isotopes of sodium are recognized. Metallic sodium is priced at about $250/kg (99.95%). On a volume basis, it is the cheapest of all metals. Sodium metal should be handled with great care. It should be kept in an inert atmosphere and contact with water and other substances with which sodium reacts should be avoided. |
| Use | Mfr of sodium cmpd, such as cyanide, azide, peroxide, itc; in mfr of tetraethyl lead; in org syntheses; for photoelectric cells; in sodium lamps; allpyed with potassium in heat transfer media. Improve structure of certain alloys, to descale metal, to purify molten metals, in reduction of org esters. Chem int for sodium hydride; chemical int & catalyst in numerous misc applications; reducing agent for metals. Laboratory reagent; coolant in nuclear reactors; electric power cable(encased in polyethylene); radioactive forms in tracer studies & medicine; heat transfer agent in solar-powered electric generators. |
| Consumption Patterns | 80% as a chemical intermediate for tetraalkyl lead gasoline additives; 7% as a reducing agent for metals; 13% in other applications (1974) Lead antiknocks (tetraethyl and tetramethyl lead), 30%; Titanium reduction, 27%; Misc, including catalysts, pulp bleaching metal descaling, dyes, pharmaceuticals, perfumes, and herbicide, 23%; exports, 20% (1985) |
| Apparent Color | Light, silvery-white metal; body-centered cubic structure; lustrous when freshly cut. |
| Boiling Point | 881.4 deg C |
| Melting Point | 97.82 deg C |
| Molecular Weight | 22.98977 |
| Density | SP GR: 0.968 @ 20 deg C/4 deg C |
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Sensitivity Data |
Fumes from burning sodium are highly irritating to skin, eyes & mucous membranes. |
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Chemical and Physical Properties |
Alkali metal Heat capacity of solid: 0.292 cal/g deg; Heat capacity of liquid @ MP: 0.331 cal/g deg; Soft at ordinary temp, fairly hard @ -20 deg C; Heat of fusion: 27.05 cal/g; Thernal conductivity (cal/sec deg C CM): 0.205 (97.82 deg C) 0.170 (400 deg C); Atomic number 11; Valence 1. Ccombines directly with halogens, with phosphorus; reduces most oxides to elemental state, reduces metallic chlorides; when heated in ammonia gas yeilds sodamide; dissolves in mercury, forming sodium amalgam; dissolves in liq ammonia to give blue soln; natural isotope: 23 (100%). Pure metallic sodium burns in air to form sodium oxide which readily takes up water to form sodium hydroxide; combined with chlorine, it forms sodium chloride (common salt), & with nitric acid, it forms sodium nitrate. Has excellent electrical conductivity & high heat absorbing capacity. Violently decomposes water, forming sodium hydroxide & hdrogen which may ignite spontaneously. Dangerous, when exposed to heat or flame, or by chemical reaction with moisture, air, ir any oxidizing material; reacts exothermally with halogens, acids & halogenated hyrdocarbons. Heated sodium is spontaneously flammable in air. Sodium, reduced to fine state of subdivision, when mixed with lead oxide ignites spontaneously. |
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Environmental Fate |
Occurrence in earth's crust: 2.83% by wt; Principal cation in hydrosphere. Found in form of its cmpd, halides, silicates, carbonates; does not occur free. Sodium is present in fair abundance in sun & stars. D-lines of sodium are among most prominent in solar spectrum. 6th most abundant element on earth most abundant of alkali group of metals most common cmpd is sodium chloride other minerals soda niter, cryolite, amphibole, zeolite, sodalite. |
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