sodium nitrate, chemical compound, NaNO₃, a colorless, odorless crystalline compound that closely resembles potassium nitrate (saltpeter or niter) in appearance and chemical properties. It is soluble in water, alcohol, and liquid ammonia. Sodium nitrate is also called soda niter or Chile saltpeter. It is found naturally in large deposits in arid regions of Chile, Peru, Argentina, and Bolivia as caliche, a crude, impure nitrate rock or gravel. Natural deposits are the major source of sodium nitrate; it is also obtained in small amounts as a byproduct of chlorine production by the nitrosyl chloride process, in which sodium chloride (common salt) is reacted with nitric acid. Sodium nitrate is used in making potassium nitrate, fertilizers, and explosives. It was formerly an important raw material for the production of nitric acid.

silver nitrate, chemical compound, AgNO₃, a colorless crystalline material that is very soluble in water. The most important compound of silver, it is used in the preparation of silver salts for photography, in chemical analysis, in silver plating, in inks and hair dyes, and to silver mirrors. It is used in medicine in the treatment of eye infections and gonorrhea. Fused silver nitrate is also called lunar caustic. Taken internally silver nitrate is a poison. It is prepared by reaction of nitric acid with silver, and purified by recrystallization. It is darkened by sunlight or contact with organic matter such as the skin.

potassium nitrate, chemical compound, KNO₃, occurring as colorless, prismatic crystals or as a white powder; it is found pure in nature as the mineral saltpeter, or niter. (The name saltpeter is also applied to sodium nitrate, although less frequently.) It is slightly soluble in cold water and very soluble in hot water. Potassium nitrate is prepared commercially by the reaction of potassium chloride with sodium nitrate. When potassium nitrate decomposes (on heating) it releases oxygen; it has been used extensively as the oxygen-supplying component of gunpowder since about the 12th cent. It is also used in explosives, fireworks, model rocket propellants, matches, and fertilizers, as a preservative in foods (especially meats), and in the manufacture of nitric acid and of glass.

nitrate, chemical compound containing the nitrate (NO₃) radical. Nitrates are salts or esters of nitric acid, HNO₃, formed by replacing the hydrogen with a metal (e.g., sodium or potassium) or a radical (e.g., ammonium or ethyl). Some important inorganic nitrates are potassium nitrate (KNO₃), sodium nitrate (NaNO₃), silver nitrate (AgNO₃), and ammonium nitrate (NH₄NO₃). Calcium nitrate is used in fertilizers; barium and strontium nitrates are used to color fireworks and signal flares; bismuth nitrate is used in making pharmaceuticals. Saltpeter (potassium nitrate), a diuretic, was once believed to be an anaphrodesiac. Nearly all metal nitrates are readily soluble in water; for this reason they are often used when a water soluble salt of a metal is needed. The presence of nitrates in the soil is of great importance, since it is from these compounds that plants obtain the nitrogen necessary for their growth. Nitrogen-fixing bacteria are important in keeping the soil supplied with nitrates. Because of the widespread use of artificial fertilizers containing nitrates, nitrates have contaminated both ground and surface waters in some agricultural areas. Organic nitrates are esters formed by reaction of nitric acid with the hydroxyl (-OH) group in an alcohol. Nitroglycerin is the trinitrate of glycerol; guncotton is a nitrate of cellulose. In chemical analysis, a test for nitrates involves the addition of a solution of ferrous sulfate to the substance to be tested, followed by the addition (without mixing) of a few drops of concentrated sulfuric acid; the presence of a nitrate is indicated by the formation of a brown ring—of Fe(NO)⁺² complex ion—where the sulfuric acid contacts the test mixture.

ammonium nitrate, chemical compound, NH₄NO₃, that exists as colorless, rhombohedral crystals at room temperature but changes to monoclinic crystals when heated above 32°C;. It is extremely soluble in water and soluble in alcohol and liquid ammonia. It is prepared commercially by reaction of nitric acid and ammonia. Major uses are in fertilizers and explosives. For fertilizers it is in the form of small clay-coated pellets. For explosives it is sometimes mixed with other substances, e.g., TNT, so that it is more easily detonated. It is also used in solid-fuel rocket propellants, in pyrotechnics, and in the production of nitrous oxide.

Inorganic compound (AgNO₃), colourless, transparent crystals with a bitter, caustic, metallic taste. The most important silver compound, it is used to prepare other silver salts, to silver mirrors, and as a reagent in analysis. It is very soluble in water; dilute solutions are effective against gonococcal bacteria and may be applied to newborns' eyes to prevent blindness from gonorrhea. Ingesting silver nitrate causes violent abdominal pain and gastroenteritis.

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Any salt or ester of nitric acid (HNO₃). The salts are inorganic compounds with ionic bonds, containing the nitrate ion (NO₃⁻) and any cation. Many, particularly ammonium nitrate, are used as agricultural fertilizers (see saltpeter). Their runoff in surface water and groundwater can cause serious illness in humans. The esters are organic compounds with covalent bonds, having the structure RsinglehorzbondOsinglehorzbondNO₂, in which R represents an organic combining group such as methyl, ethyl, or phenyl.

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