Salt (chemistry)
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In
chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, properties ...
, a salt is a
chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A homonuclear molecule, molecule co ...
consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net
electric charge Electric charge is the physical property of matter that causes charged matter to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative'' (commonly carried by protons and electron ...
. A common example is
table salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistry), salts; salt in the form of a natural crystallinity, crystalline mineral is known as rock salt or halite. ...
, with positively charged
sodium Sodium is a chemical element with the Symbol (chemistry), symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the ...
ions and negatively charged
chloride The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the chemical element, element chlorine (a halogen) gains an electron or when a chemical compound, compound such as hydrogen chloride is dissolved in water or o ...
ions. The component ions in a salt compound can be either
inorganic In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistr ...
, such as
chloride The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the chemical element, element chlorine (a halogen) gains an electron or when a chemical compound, compound such as hydrogen chloride is dissolved in water or o ...
(Cl), or organic, such as
acetate An acetate is a salt (chemistry), salt formed by the combination of acetic acid with a base (e.g. Alkali metal, alkaline, Alkaline earth metal, earthy, Transition metal, metallic, nonmetallic or radical Radical (chemistry), base). "Acetate" als ...
(). Each ion can be either
monatomic In physics and chemistry, "monatomic" is a combination of the words "mono" and "atomic", and means "single atom". It is usually applied to gases: a monatomic gas is a gas in which atoms are not bound to each other. Examples at Standard temperature ...
, such as
fluoride Fluoride (). According to this source, is a possible pronunciation in British English. is an Inorganic chemistry, inorganic, Monatomic ion, monatomic Ion#Anions and cations, anion of fluorine, with the chemical formula (also written ), whose ...
(F), or polyatomic, such as
sulfate The sulfate or sulphate ion is a polyatomic ion, polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salt (chemistry), ...
().


Types of salt

Salts can be classified in a variety of ways. Salts that produce
hydroxide Hydroxide is a polyatomic ion, diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually Self-ionization ...
ions An ion () is an atom or molecule with a net electric charge, electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be po ...
when dissolved in
water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
are called '' alkali salts'' and salts that produce
hydrogen Hydrogen is the chemical element with the Symbol (chemistry), symbol H and atomic number 1. Hydrogen is the lightest element. At standard temperature and pressure, standard conditions hydrogen is a gas of diatomic molecules having the chemical ...
ions An ion () is an atom or molecule with a net electric charge, electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be po ...
when dissolved in
water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
are called ''
acid salt Acid salts are a class of salt (chemistry), salts that produce an acidic solution after being dissolved in a solvent. Its formation as a substance has a greater electrical conductivity than that of the pure solvent. An acidic solution formed by acid ...
s''. ''Neutral salts'' are those salts that are neither acidic nor basic.
Zwitterion In chemistry, a zwitterion ( ; ), also called an inner salt or dipolar ion, is a molecule that contains an equal number of positively- and negatively-charged functional groups. : With amino acids, for example, in solution a equilibrium chemistry, c ...
s contain an anionic and a cationic centre in the same
molecule A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...
, but are not considered salts. Examples of zwitterions are
amino acid Amino acids are organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon chemical bond, bonds. Due to carbon's ability to Catenation, catenate (form chains with ot ...
s, many
metabolite In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...
s,
peptide Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptide ...
s, and
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metabo ...
s.


Properties


Color

Solid salts tend to be transparent, as illustrated by
sodium chloride Sodium chloride , commonly known as salt (although sea salt also contains other chemical salt (chemistry), salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of ...
. In many cases, the apparent opacity or transparency are only related to the difference in size of the individual
monocrystal In materials science, a single crystal (or single-crystal solid or monocrystalline solid) is a material in which the crystal lattice of the entire sample is continuous and unbroken to the edges of the sample, with no Grain boundary, grain bound ...
s. Since light reflects from the
grain boundaries In materials science, a grain boundary is the interface between two grains, or crystallites, in a polycrystalline material. Grain boundaries are two-dimensional crystallographic defect, defects in the crystal structure, and tend to decrease the ...
(boundaries between crystallites), larger
crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macrosc ...
s tend to be transparent, while the
polycrystalline A crystallite is a small or even microscopic crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal latt ...
aggregates look like opaque powders or masses. Salts exist in many different
color Color (American English) or colour (British English) is the visual perception, visual perceptual Physical property, property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physica ...
s, which arise either from their constituent anions, cations or solvates. For example: * sodium chromate is made yellow by the
chromate ion Chromate salts contain the chromate anion, . Dichromate salts contain the dichromate anion, . They are oxyanions of chromium in the +6 oxidation state and are moderately strong oxidizing agents. In an aqueous Solution (chemistry), solution, chr ...
*
potassium dichromate Potassium dichromate, , is a common inorganic compound, inorganic chemical reagent, most commonly used as an oxidizing agent in various laboratory and industrial applications. As with all hexavalent chromium compounds, it is acutely and chronical ...
is made orange by the dichromate ion * cobalt nitrate is made red by the chromophore of hydrated cobalt(II) ( o(H2O)6sup>2+). *
copper sulfate Copper sulfate may refer to: * Copper(II) sulfate, CuSO4, a common compound used as a fungicide and herbicide * Copper(I) sulfate, Cu2SO4, which is uncommonly used * Copper(II) sulfate, CuSO4 is greenish blue Copper compounds {{Chem-stu ...
is made blue by the copper(II) chromophore *
potassium permanganate Potassium permanganate is an inorganic compound with the chemical formula KMnO4. It is a purplish-black crystalline salt, that dissolves in water as potassium ion, K+ and permanganate, , an intensely pink to purple solution. Potassium permangan ...
is made violet by the
permanganate A permanganate () is a chemical compound containing the manganate(VII) ion, , the conjugate base of permanganic acid. Because the manganese atom is in the +7 oxidation state, the permanganate(VII) ion is a strong oxidizing agent. The ion is a tra ...
anion. * nickel chloride is typically made green by the hydrated nickel(II) chloride iCl2(H2O)4*
sodium chloride Sodium chloride , commonly known as salt (although sea salt also contains other chemical salt (chemistry), salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of ...
, magnesium sulfate heptahydrate appear colorless or white because the constituent cations and anions do not absorb light in the part of the spectrum that is visible to humans. Few
minerals In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...
are salts, because they would be solubilized by water. Similarly, inorganic
pigment A pigment is a colored material that is completely or nearly Solubility, insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorg ...
s tend not to be salts, because insolubility is required for fastness. Some organic
dye A dye is a color Color (American English) or colour (British English) is the visual perception, visual perceptual Physical property, property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color c ...
s are salts, but they are virtually insoluble in water.


Taste

Different salts can elicit all five basic tastes, e.g., salty (
sodium chloride Sodium chloride , commonly known as salt (although sea salt also contains other chemical salt (chemistry), salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of ...
),
sweet Sweetness is a Taste#Basic tastes, basic taste most commonly Perception, perceived when eating foods rich in sugars. Sweet tastes are generally regarded as pleasure, pleasurable. In addition to sugars like sucrose, many other chemical compounds ...
( lead diacetate, which will cause
lead poisoning Lead poisoning, also known as plumbism and saturnism, is a type of metal poisoning caused by lead in the body. The brain is the most sensitive. Symptoms may include abdominal pain, constipation, headaches, irritability, memory problems, infertil ...
if ingested),
sour The gustatory system or sense of taste is the sensory system that is partially responsible for the perception of taste (flavor). Taste is the perception produced or stimulated when a substance in the mouth biochemistry, reacts chemically with ta ...
(
potassium bitartrate Potassium bitartrate, also known as potassium hydrogen tartrate, with formula potassium, KCarbon, C4hydrogen, H5oxygen, O6, is a byproduct of winemaking. In cooking, it is known as cream of tartar. It is processed from the potassium acid salt ...
), bitter (
magnesium sulfate Magnesium sulfate or magnesium sulphate (in English-speaking countries other than the US) is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) cont ...
), and
umami Umami ( from ja, 旨味 ), or savoriness, is one of the five Taste#Basic tastes, basic tastes. It has been described as savory and is characteristic of broths and cooked meats. People taste umami through taste receptors that typically respond ...
or savory (
monosodium glutamate Monosodium glutamate (MSG), also known as sodium glutamate, is the sodium Salt (chemistry), salt of glutamic acid. MSG is found naturally in some foods including tomatoes and cheese in this glutamic acid form. MSG is used in cooking as a fl ...
).


Odor

Salts of strong acids and strong bases (" strong salts") are non- volatile and often odorless, whereas salts of either weak acids or weak bases (" weak salts") may smell like the
conjugate acid A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid protonation, donates a proton () to a base (chemistry), base—in other words, it is a base with a hydrogen ion added to it, as in the ...
(e.g., acetates like acetic acid (
vinegar Vinegar is an aqueous solution of acetic acid and trace compounds that may include flavorings. Vinegar typically contains 5–8% acetic acid by volume. Usually, the acetic acid is produced by a double fermentation, converting simple sugars to eth ...
) and cyanides like
hydrogen cyanide Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on ...
(
almond The almond (''Prunus amygdalus'', Synonym (taxonomy)#Botany, syn. ''Prunus dulcis'') is a species of tree native to Iran and surrounding countries, including the Levant. The almond is also the name of the edible and widely cultivated seed of th ...
s) or the conjugate base (e.g., ammonium salts like
ammonia Ammonia is an inorganic chemical compound, compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a dis ...
) of the component ions. That slow, partial decomposition is usually accelerated by the presence of water, since
hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...
is the other half of the
reversible reaction A reversible reaction is a reaction in which the conversion of reactants to products and the conversion of products to reactants occur simultaneously. : \mathit aA + \mathit bB \mathit cC + \mathit dD A and B can react to form C and D or, in the ...
equation of formation of weak salts.


Solubility

Many ionic compounds exhibit significant
solubility In chemistry, solubility is the ability of a chemical substance, substance, the solute, to form a solution (chemistry), solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form su ...
in water or other polar solvents. Unlike molecular compounds, salts dissociate in solution into anionic and cationic components. The
lattice energy In chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, struct ...
, the cohesive forces between these ions within a solid, determines the solubility. The solubility is dependent on how well each ion interacts with the solvent, so certain patterns become apparent. For example, salts of
sodium Sodium is a chemical element with the Symbol (chemistry), symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the ...
,
potassium Potassium is the chemical element with the Symbol (chemistry), symbol K (from New Latin, Neo-Latin ''wikt:kalium#Latin, kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little fo ...
and ammonium are usually soluble in water. Notable exceptions include
ammonium hexachloroplatinate Ammonium hexachloroplatinate, also known as ammonium chloroplatinate, is the inorganic compound with the formula (NH4)2 tCl6 It is a rare example of a soluble platinum(IV) salt (chemistry), salt that is not hygroscopy, hygroscopic. It forms int ...
and potassium cobaltinitrite. Most
nitrates Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in wat ...
and many
sulfate The sulfate or sulphate ion is a polyatomic ion, polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salt (chemistry), ...
s are water-soluble. Exceptions include
barium sulfate Barium sulfate (or sulphate) is the inorganic compound with the chemical formula Barium, BaSulfate, SO4. It is a white crystalline solid that is odorless and Solubility, insoluble in water. It occurs as the mineral barite, which is the main comme ...
,
calcium sulfate Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO4 and related hydrates. In the form of γ-anhydrite (the anhydrous form), it is used as a desiccant. One particular hydrate is better known as plaster of Paris, ...
(sparingly soluble), and
lead(II) sulfate Lead(II) sulfate (PbSO4) is a white solid, which appears white in microcrystalline form. It is also known as ''fast white'', ''milk white'', ''sulfuric acid lead salt'' or ''anglesite''. It is often seen in the plates/electrodes of lead–acid ba ...
, where the 2+/2− pairing leads to high lattice energies. For similar reasons, most metal
carbonate A carbonate is a salt (chemistry), salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containin ...
s are not soluble in water. Some soluble carbonate salts are:
sodium carbonate Sodium carbonate, , (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield moderately alkaline solutions ...
,
potassium carbonate Potassium carbonate is the inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a sub ...
and
ammonium carbonate Ammonium carbonate is a salt with the chemical formula (NH4)2CO3. Since it readily degrades to gaseous ammonia and carbon dioxide upon heating, it is used as a leavening agent and also as smelling salt. It is also known as baker's ammonia and is ...
.


Conductivity

Salts are characteristically insulators. Molten salts or solutions of salts conduct electricity. For this reason, liquified (molten) salts and solutions containing dissolved salts (e.g., sodium chloride in water) can be used as
electrolyte An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electron The electron ( or ) is a subatomic particle with a negative one elementary charge, elementary electr ...
s.


Melting point

Salts characteristically have high melting points. For example,
sodium chloride Sodium chloride , commonly known as salt (although sea salt also contains other chemical salt (chemistry), salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of ...
melts at 801 °C. Some salts with low lattice energies are liquid at or near room temperature. These include
molten salt Molten salt is salt (chemistry), salt which is solid at standard temperature and pressure but enters the liquid phase due to elevated temperature. Regular Salt, table salt has a melting point of 801 °C (1474°F) and a heat of fusion of 520 J/ ...
s, which are usually mixtures of salts, and
ionic liquid An ionic liquid (IL) is a salt (chemistry), salt in the liquid state. In some contexts, the term has been restricted to salts whose melting point is below a specific temperature, such as . While ordinary liquids such as water and gasoline are pred ...
s, which usually contain organic cations. These liquids exhibit unusual properties as solvents.


Nomenclature

The name of a salt starts with the name of the cation (e.g., ''sodium'' or ''ammonium'') followed by the name of the anion (e.g., ''chloride'' or ''acetate''). Salts are often referred to only by the name of the cation (e.g., ''sodium salt'' or ''ammonium salt'') or by the name of the anion (e.g., ''chloride salt'' or ''acetate salt''). Common salt-forming cations include: *
Ammonium The ammonium cation is a positively-charged polyatomic ion with the chemical formula or . It is formed by the protonation of ammonia (). Ammonium is also a general name for positively charged or protonated substituted amines and quaternary amm ...
*
Calcium Calcium is a chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. Unlike chemica ...
*
Iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundance ...
and *
Magnesium Magnesium is a chemical element with the Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group ...
*
Potassium Potassium is the chemical element with the Symbol (chemistry), symbol K (from New Latin, Neo-Latin ''wikt:kalium#Latin, kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little fo ...
*
Pyridinium Pyridinium refers to the cation . It is the conjugate acid of pyridine. Many related cations are known involving substituted pyridines, e.g. picolines, lutidines, collidines. They are prepared by treating pyridine with acids. As pyridine is oft ...
*
Quaternary ammonium In chemistry, quaternary ammonium cations, also known as quats, are positively charged polyatomic ions of the structure , R being an alkyl group or an aryl group. Unlike the ammonium, ammonium ion () and the primary, secondary, or tertiary ammoni ...
, R being an
alkyl In organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that ...
group or an
aryl In organic chemistry, an aryl is any functional group or substituent derived from an aromaticity, aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar ...
group *
Sodium Sodium is a chemical element with the Symbol (chemistry), symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the ...
*
Copper Copper is a chemical element with the Symbol (chemistry), symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductility, ductile metal with very high thermal conductivity, thermal and electrical conductivity. A fre ...
Common salt-forming anions (parent acids in parentheses where available) include: *
Acetate An acetate is a salt (chemistry), salt formed by the combination of acetic acid with a base (e.g. Alkali metal, alkaline, Alkaline earth metal, earthy, Transition metal, metallic, nonmetallic or radical Radical (chemistry), base). "Acetate" als ...
(
acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon chemical bond, bond ...
) *
Carbonate A carbonate is a salt (chemistry), salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containin ...
( carbonic acid) *
Chloride The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the chemical element, element chlorine (a halogen) gains an electron or when a chemical compound, compound such as hydrogen chloride is dissolved in water or o ...
(
hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungency, pungent smell. It is classified as a acid strength, strong acid. It is a component of the gas ...
) *
Citrate Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a Transparency and translucency, colorless Weak acid, weak organic acid. It occurs naturally in Citrus, citrus fruits. In biochemistry, it is an intermedi ...
(
citric acid Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a Transparency and translucency, colorless Weak acid, weak organic acid. It occurs naturally in Citrus, citrus fruits. In biochemistry, it is an intermedi ...
) *
Cyanide Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms. In chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers th ...
( hydrocyanic acid) *
Fluoride Fluoride (). According to this source, is a possible pronunciation in British English. is an Inorganic chemistry, inorganic, Monatomic ion, monatomic Ion#Anions and cations, anion of fluorine, with the chemical formula (also written ), whose ...
(
hydrofluoric acid Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colourless, acidic and highly corrosive. It is used to make most fluorine-containing compounds; examples include the commonly used pharmaceutical antidep ...
) *
Nitrate Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in wat ...
(
nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available ni ...
) *
Nitrite The nitrite polyatomic ion, ion has the chemical formula . Nitrite (mostly sodium nitrite) is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name ...
(
nitrous acid Nitrous acid (molecular formula ) is a weak and monoprotic acid known only in solution, in the gas phase and in the form of nitrite () salts. Nitrous acid is used to make diazonium salts from amines. The resulting diazonium salts are reage ...
) *
Oxide An oxide () is a chemical compound that contains at least one oxygen atom and one other chemical element, element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of ...
(
water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
) *
Phosphate In chemistry, a phosphate is an anion, salt (chemistry), salt, functional group or ester derived from a phosphoric acids and phosphates, phosphoric acid. It most commonly means orthophosphate, a derivative of phosphoric acid, orthophosphoric a ...
(
phosphoric acid Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula . It is commonly encountered as an 85% aqueous solution, w ...
) *
Sulfate The sulfate or sulphate ion is a polyatomic ion, polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salt (chemistry), ...
(
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen ...
) Salts with varying number of hydrogen atoms replaced by cations as compared to their parent acid can be referred to as ''monobasic'', ''dibasic'', or ''tribasic'', identifying that one, two, or three hydrogen atoms have been replaced; ''polybasic'' salts refer to those with more than one hydrogen atom replaced. Examples include: * Sodium phosphate monobasic (NaH2PO4) * Sodium phosphate dibasic (Na2HPO4) * Sodium phosphate tribasic (Na3PO4)


Formation

Salts are formed by a
chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...
between: *A base and an
acid An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen ion, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid A Lewis acid (named for the American p ...
, e.g., NH3 + HClNH4Cl *A
metal A metal (from ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, e ...
and an
acid An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen ion, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid A Lewis acid (named for the American p ...
, e.g., Mg + H2SO4MgSO4 + H2 *A metal and a non-metal, e.g., Ca + Cl2CaCl2 *A base and an
acid anhydride An acid anhydride is a type of chemical compound derived by the removal of water molecules from an acid (chemistry), acid. In organic chemistry, organic acid anhydrides contain the functional group R(CO)O(CO)R'. Organic acid anhydrides often form w ...
, e.g., 2  NaOH + Cl2O → 2  NaClO + H2O *An
acid An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen ion, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid A Lewis acid (named for the American p ...
and a base anhydride, e.g., 2  HNO3 + Na2O → 2  NaNO3 + H2O *In the
salt metathesis reaction A salt metathesis reaction, sometimes called a double displacement reaction, is a chemical process involving the exchange of chemical bond, bonds between two reacting chemical species which results in the creation of products with similar or ident ...
where two different salts are mixed in water, their ions recombine, and the new salt is insoluble and precipitates. For example: *: Pb(NO3)2 + Na2SO4 → PbSO4↓ + 2 NaNO3


Strong salt

Strong salts or strong
electrolyte An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electron The electron ( or ) is a subatomic particle with a negative one elementary charge, elementary electr ...
salts are chemical salts composed of strong electrolytes. These
ionic compound In chemistry, an ionic compound is a chemical compound composed of ions held together by Coulomb's law, electrostatic forces termed ionic bonding. The compound is neutral overall, but consists of positively charged ions called cations and negativ ...
s dissociate completely in
water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
. They are generally odorless and nonvolatile. Strong salts start with Na__, K__, NH4__, or they end with __NO3, __ClO4, or __CH3COO. Most group 1 and 2 metals form strong salts. Strong salts are especially useful when creating conductive compounds as their constituent ions allow for greater conductivity.


Weak salt

Weak salts or "weak electrolyte salts" are, as the name suggests, composed of weak
electrolyte An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electron The electron ( or ) is a subatomic particle with a negative one elementary charge, elementary electr ...
s. They are generally more volatile than strong salts. They may be similar in
odor An odor (American English American English, sometimes called United States English or U.S. English, is the set of variety (linguistics), varieties of the English language native to the United States. English is the Languages of the Uni ...
to the
acid An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen ion, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid A Lewis acid (named for the American p ...
or base they are derived from. For example,
sodium acetate Sodium acetate, CH3COONa, also abbreviated Na O Ac, is the sodium salt of acetic acid. This colorless deliquescent Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption (chemistry), absorption or ad ...
, CH3COONa, smells similar to
acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon chemical bond, bond ...
CH3COOH.


See also

* Bresle method (the method used to test for salt presence during coating applications) *
Carboxylate In organic chemistry, a carboxylate is the conjugate base of a carboxylic acid, (or ). It is an ion with negative charge. Carboxylate salts are salt (chemistry), salts that have the general formula , where M is a metal and ''n'' is 1, 2, ...
* Fireworks/pyrotechnics (salts are what give color to fireworks) *
Halide In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom Every atom is composed of a atomic nucleus, nucleus and one or more electrons bound to the nucleus. The nucleus is made of o ...
*
Ionic bond Ionic bonding is a type of chemical bonding that involves the Coulomb's law, electrostatic attraction between oppositely charged ions, or between two atoms with sharply different electronegativities, and is the primary interaction occurring in ion ...
s *
Natron Natron is a naturally occurring mixture of sodium carbonate decahydrate (sodium carbonate, Na2CO3·10H2O, a kind of soda ash) and around 17% sodium bicarbonate (also called baking soda, NaHCO3) along with small quantities of sodium chloride and ...
*
Salinity Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...


References

* Mark Kurlansky (2002). ''Salt: A World History''. Walker Publishing Company. . {{Authority control Chemical compounds Alchemical substances