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salt,chemical compound (other than water) formed by a chemical reaction between an acid and a base (see acids and basesacids and bases,
two related classes of chemicals; the members of each class have a number of common properties when dissolved in a solvent, usually water. Properties
..... Click the link for more information. ).
Characteristics and Classification of Salts
The most familiar salt is sodium chloridesodium chloride,
NaCl, common salt. Properties
Sodium chloride is readily soluble in water and insoluble or only slightly soluble in most other liquids. It forms small, transparent, colorless to white cubic crystals.
..... Click the link for more information. , the principal component of common table salt. Sodium chloride, NaCl, and water, H2O, are formed by neutralizationneutralization,
chemical reaction, according to the Arrhenius theory of acids and bases, in which a water solution of acid is mixed with a water solution of base to form a salt and water; this reaction is complete only if the resulting solution has neither acidic nor basic
..... Click the link for more information. of sodium hydroxide, NaOH, a base, with hydrogen chloride, HCl, an acid: HCl+NaOH→NaCl+H2O. Most salts are ionic compounds (see chemical bondchemical bond,
mechanism whereby atoms combine to form molecules. There is a chemical bond between two atoms or groups of atoms when the forces acting between them are strong enough to lead to the formation of an aggregate with sufficient stability to be regarded as an
..... Click the link for more information. ); they are made up of ionsion,
atom or group of atoms having a net electric charge. Positive and Negative Electric Charges
A neutral atom or group of atoms becomes an ion by gaining or losing one or more electrons or protons.
..... Click the link for more information. rather than molecules. The chemical formulaformula,
in chemistry, an expression showing the chemical composition of a compound. Formulas of compounds are used in writing the equations (see chemical equations) that represent chemical reactions. Compounds are combinations in fixed proportions of the chemical elements.
..... Click the link for more information. for an ionic salt is an empirical formula; it does not represent a molecule but shows the proportion of atoms of the elements that make up the salt. The formula for sodium chloride, NaCl, indicates that equal numbers of sodium and chlorine atoms combine to form the salt. In the reaction of sodium with chlorine, each sodium atom loses an electron, becoming positively charged, and each chlorine atom gains an electron, becoming negatively charged (see oxidation and reductionoxidation and reduction,
complementary chemical reactions characterized by the loss or gain, respectively, of one or more electrons by an atom or molecule. Originally the term oxidation
..... Click the link for more information. ); there are equal numbers of positively charged sodium ions and negatively charged chloride ions in sodium chloride. The ions in a solid salt are usually arranged in a definite crystalline structure, each positive ion being associated with a fixed number of negative ions, and vice versa.
A salt that has neither hydrogen (H) nor hydroxyl (OH) in its formula, e.g., sodium chloride (NaCl), is called a normal salt. A salt that has hydrogen in its formula, e.g., sodium bicarbonate (NaHCO3), is called an acid salt. A salt that has hydroxyl in its formula, e.g., basic lead nitrate (Pb[OH]NO3), is called a basic salt. Since a salt may react with a solvent to yield different ions than were present in the salt (see hydrolysishydrolysis
, chemical reaction of a compound with water, usually resulting in the formation of one or more new compounds. The most common hydrolysis occurs when a salt of a weak acid or weak base (or both) is dissolved in water.
..... Click the link for more information. ), a solution of a normal salt may be acidic or basic; e.g., trisodium phosphate, Na3PO4, dissolves in and reacts with water to form a basic solution.
In addition to being classified as normal, acid, or basic, salts are categorized as simple salts, double salts, or complex salts. Simple salts, e.g., sodium chloride, contain only one kind of positive ion (other than the hydrogen ion in acid salts). Double salts contain two different positive ions, e.g., the mineral dolomite, or calcium magnesium carbonate, CaMg(CO3)2. Alumsalum
, any one of a series of isomorphous double salts that are hydrated sulfates of a univalent cation (e.g., potassium, sodium, ammonium, cesium, or thallium) and a trivalent cation (e.g., aluminum, chromium, iron, manganese, cobalt, or titanium).
..... Click the link for more information. are a special kind of double salt. Complex salts, e.g., potassium ferricyanide, K3Fe(CN)6, contain a complex ion that does not dissociate in solution. A hydratehydrate
, chemical compound that contains water. A common hydrate is the familiar blue vitriol, a crystalline form of cupric sulfate. Chemically, it is cupric sulfate pentahydrate, CuSO4·5H2O.
..... Click the link for more information. is a salt that includes water in its solid crystalline form; Glauber's salt and Epsom salts are hydrates.
Salts are often grouped according to the negative ion they contain, e.g., bicarbonatebicarbonate
or hydrogen carbonate,
chemical compound containing the bicarbonate radical, -HCO3. The most familiar of such compounds is sodium bicarbonate (baking soda). See carbonate.
..... Click the link for more information. or carbonatecarbonate
, chemical compound containing the carbonate radical or ion, CO3−2. Most familiar carbonates are salts that are formed by reacting an inorganic base (e.g., a metal hydroxide) with carbonic acid.
..... Click the link for more information. , chloratechlorate
, salts of chloric acid, HClO3, and perchloric acid, HClO4, respectively. Chloric Acid and Its Salts
Chloric acid, HClO3·7H2
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, chemical compound containing chlorine. Most chlorides are salts that are formed either by direct union of chlorine with a metal or by reaction of hydrochloric acid (a water solution of hydrogen chloride) with a metal, a metal oxide, or an inorganic base.
..... Click the link for more information. , cyanidecyanide
, chemical compound containing the cyano group, -CN. Cyanides are salts or esters of hydrogen cyanide (hydrocyanic acid, HCN) formed by replacing the hydrogen with a metal (e.g., sodium or potassium) or a radical (e.g., ammonium or ethyl).
..... Click the link for more information. , fulminatefulminate
, any salt of fulminic acid, HONC, a highly unstable compound known only in solution. The term is most commonly applied to the explosive mercury (II) fulminate, also called fulminate of mercury, Hg(ONC)2. The pure compound forms white cubic crystals.
..... Click the link for more information. , nitratenitrate,
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).
..... Click the link for more information. , phosphatephosphate,
salt or ester of phosphoric acid, H3PO4. Because phosphoric acid is tribasic (having three replaceable hydrogen atoms), it forms monophosphate, diphosphate, and triphosphate salts in which one, two, or three of the hydrogens of the acid are
..... Click the link for more information. , silicatesilicate,
chemical compound containing silicon, oxygen, and one or more metals, e.g., aluminum, barium, beryllium, calcium, iron, magnesium, manganese, potassium, sodium, or zirconium. Silicates may be considered chemically as salts of the various silicic acids.
..... Click the link for more information. , sulfatesulfate,
chemical compound containing the sulfate (SO4) radical. Sulfates are salts or esters of sulfuric acid, H2SO4, formed by replacing one or both of the hydrogens with a metal (e.g., sodium) or a radical (e.g., ammonium or ethyl).
..... Click the link for more information. , or sulfidesulfide,
chemical compound containing sulfur and one other element or sulfur and a radical. Sulfides may be salts or esters of hydrogen sulfide, H2S, or may be formed directly, e.g., by heating a metal with sulfur.
..... Click the link for more information. .
Preparation of Salts
Salts are also prepared by methods other than neutralization. A metal can combine directly with a nonmetal to form a salt; e.g., sodium metal reacts with chlorine gas to form sodium chloride. A metal may react with a dilute acid to form a salt and release hydrogen gas; e.g., zinc reacts with dilute sulfuric acid to form zinc sulfate and hydrogen. A metal oxide may react with an acid to form a salt and water; e.g., calcium oxide reacts with carbonic acid to form calcium carbonate and water. A base can react with a nonmetallic oxide to form a salt and water; e.g., sodium hydroxide reacts with carbon dioxide to form sodium carbonate and water. Two salts may react with one another (in solution) to form two new salts; e.g., barium chloride and sodium sulfate react in solution to form barium sulfate (as an insoluble precipitate) and sodium chloride (which remains in solution). A salt may react with an acid to form a different salt and acid; e.g., sodium chloride and sulfuric acid react when heated to form sodium sulfate and release hydrogen chloride gas (which in solution forms hydrochloric acid). A salt undergoes dissociationdissociation,
in chemistry, separation of a substance into atoms or ions. Thermal dissociation occurs at high temperatures. For example, hydrogen molecules (H2
..... Click the link for more information. when it dissolves in a polar solvent, e.g., water, the extent of dissociation depending both on the salt and the solvent.
See M. Kurlansky, Salt: A World History (2002).
SALT,Strategic Arms Limitation Talks: see disarmament, nucleardisarmament, nuclear,
the reduction and limitation of the various nuclear weapons in the military forces of the world's nations. The atomic bombs dropped (1945) on Japan by the United States in World War II demonstrated the overwhelming destructive potential of nuclear weapons
..... Click the link for more information. .
SALTAbbrev. for Southern African Large Telescope.
Salt(religion, spiritualism, and occult)
Much like iron, salt was believed to have supernatural origins and has become an essential part of most religious and magical rituals. The very word "salary" comes from the Latin salarium meaning "salt allowance," showing it to have great worth. The habitual use of salt is connected with the advance from nomadic to agricultural life. The gods were worshiped as the givers of the foods necessary for life; so salt, frequently together with bread, was associated with offerings to the deities. This was especially prevalent among the Greeks and Romans.
Since it is so essential to life—both human and animal—salt symbolically represents life. It is added to baptismal water, to water used in exorcism, and to the holy water used on a Wiccan altar. Some traditions of Witchcraft mark their Circle with salt. Magically, it is considered a great defense against evil. For this reason, people in the Middle Ages believed it to be a tool for preventing witchcraft and for destroying a witch. Even today, in the Ozarks, it is believed that if a woman complains that her food tastes too salty, she may well be a witch. There is an old saying in the region: "The Devil hates salt."
Since salt represents life, to spill salt is a bad omen for it presages spilling blood. In alchemy it represents the principle of body, the female, and earth. On the Wiccan and ceremonial altars it represents the element of earth. In the old British custom of "first-footing" (being the first person of the new year to set foot across another's doorstep), salt is one of the gifts presented by the first-footer to the homeowner.
Salt used to mark the line at the meal table between family or close friends and those who were casual visitors or menials. The former sat at the head of the table, while the latter sat "below the salt"—below where the salt cellar stood on the table.
Salt and incense were both religious and economic necessities of the ancient world. Via Lalaria, as one of the oldest roads in Italy, was used for moving the salt of Ostia to the Sabine country. Herodotus mentions the caravan route connecting the many oases of the Libyan desert as a road for the transportation of salt.
In Wiccan rituals, sea salt is the preferred type, although any regular salt is acceptable. There are various ways of processing sea salt, the traditional and possibly the oldest and purest method being by allowing the wind and sun alone to dry ocean brine that is channeled from the open sea into pristine shallow clay ponds. In this manner, Celtic Brittany farmers produce some of the finest and purest sea salt in the world.
a mountain range in northern Pakistan, between the valleys of the Indus and Jhelum rivers. The range stretches for a length of approximately 300 km, with elevations to 1,522 m (Mount Sakesar). The Salt Range constitutes a cuesta-like ledge below the southern edge of the Potwar Plateau. It is composed of crystalline rocks overlain with limestones and dolomites. There are large deposits of rock salt at Khewra and Nurpur and other sites. On the slopes there are separate pine, acacia, and olive groves.
the name of a class of chemical compounds that are crystalline under ordinary conditions and for which an ionic structure is typical. According to the theory of electrolytic dissociation, salts are chemical compounds that in solution dissociate into positively charged ions, or cations (mainly, of metals), and negatively charged ions, or anions. The various types of salts include normal, acid, basic, double, mixed, and complex salts. The most common laboratory method for the preparation of salts is the reactions of acids with bases, as well as reactions of acids with metals and, in many cases (depending on the electromotive forces series), reactions of salts themselves with metals.
A characteristic property of salts is solubility in polar solvents, especially water. In nature, accumulations of salts are formed mainly by sedimentation from aqueous solutions in inland sea basins (Aral Sea, Dead Sea) or in inlets almost cut off from the sea (Kara-Bogaz-Gol), as well as in closed mainland lakes (El’ton, Baskunchak).
Salts were known in antiquity. In addition to their traditional use in foods and medicine, salts came to be used industrially with the development of the chemical, glassmaking, leather, textile, and metallurgical industries. Some salts are used as mineral fertilizers.
REFERENCENekrasov, B. V. Osnovy obshchei khimii, vols. [1–2], 3rd ed. Moscow, 1973.
What does it mean when you dream about salt?
Used as seasoning in food, salt symbolizes flavor or piquancy. As one of the three primary elements of matter in alchemy representing—in contrast to mercury and sulfur—the principle of fixity and solidity, salt symbolizes someone who is steadfast and dependable, “the salt of the earth.”
SALT(1) (Speech Application Language Tags) Extensions to HTML, XHTML and XML for voice recognition and synthesized speech and audio output. SALT is designed to support mixed modes including audio, video, text and graphics, depending on the device in the user's hands. For more information, visit the SALT Forum at www.saltforum.org.
(2) (salt) In cryptography, a random number that is added to the encryption key or to a password to protect them from disclosure. See cryptography.