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A salt, in chemistry, is an electrically neutral chemical compound^[1] consists of the set of more ions (anions and cations),^[2] typically arranged within a crystalline reticle, united by an ionic bond of more or less elevated ionity.

Salts have different degree of solubility in the various solvents. In a saline solution we see a phenomenon called hebullioscopic rise (increasing the boiling point) and cryoscopic lowering (lowening of the freezing point) compared to pure solvent.

Salts can be obtained by replacing the hydrogen atoms of an acid with metal atoms or with a functional group that may show metallic or cationic behaviour (for example ammonium group, NH₄⁺). Being made up of ions, salts are "Ionic compounds"; they can be organic or inorganic, simple or complex, binary, ternary, etc. (consisting of a different number of chemical elements). They have variable and different external characteristics (colour, smell, flavour, transparency) depending on their composition.

They can be, depending on the characteristics of the ionic bond, and the polarity of the resulting hydrolyzed ions, very soluble or completely insoluble in water, where the two groups united by ion bond are dissociated. They are also soluble in other solvents, and typically the salts formed by strong electrolytes dissolve well into polar solvents such as water. Salts have a variable melting point, often low hardness, and low compressibility.

If fused or dissolved in water are called electrolytes and lead electricity proportionally to the electronegativeness of constituent atoms, acting as conductors of second species. The two elements of a binary salt (such as sodium chloride) can be obtained by electrolysis of molten salt. What is commonly called salt or kitchen rooms is actually one of the many possible salts, i.e. sodium chloride (NaCl).

Types of salts

In addition to the best known simple, binary and inorganic ternarian salts, there are numerous features of more complex molecules. Salts can be acidic or basic depending on the...Explore this chapter

In addition to the best known simple, binary and inorganic ternarian salts, there are numerous features of more complex molecules. Salts can be acidic or basic depending on the level of substitution of the anionic and cationic component of the compound (sodium acid carbonate, or bicarbonate, an example of the first case, cobalt chloride, basic barium chloride or barium hydroxychloride in the second), simple as sodium chloride or double, triple, etc. such as potassium or chromium alum. heteropoly acids), such as potassium ferrocyanide, ironic acid, sodium phosphomolydated by phosphorus acid, or be compounds that[ formally salts, assume characteristics similar to a alloy, like gallium arsenide semiconductors and indium phosphire. Organic acids such as carboxylic acids,]] sulphonic acids, phosphonics, etc. also form the corresponding salts (diidrossiazonaftalen-trisulphonate of sodium, phosphonate, and so on).

Some reactions that produce salts

NB: there are other ways to get salts starting from salts, including: salt + acid, salt + non-metal, salt + hydroxide, salt + salt.Explore this chapter

Reagent	Result	Example equation
hydroxide + acid	salt + water	${\displaystyle}2\,\mathrm {NaOH} {}+{}\mathrm {H} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {SO} {\vphantom {A}}_{\smash[{t}]{4}}{\mathrel {\longrightarrow}\mathrm {Na} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {SO} {\vphantom {A}}_{\smash[{t}]{4}}{}+{}2\,\mathrm {H} {\vphantom {A}}_{\smash[{t}]{2}}$ (sodium sulphate)
metal + acid	salt + hydrogen	${\mathrm {Zn}+{\mathrm {H} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {SO} {\vphantom {A}}_{\smash[{t}]{4}}{\mathrel {\longrightarrow}\mathrm {ZnSO} {\vphantom {A}}_{\smash[{t]}{4}}{\mathrm {H} {\vphantom {A}}_{\smash[{t}]{2}}}$ (zinc sulphate)
Dioxide + basic oxide	salt (ternary)	${\mathrm {CO} {\vphantom {A}}_{\smash[{t}]{2}}{\mathrm {CaO}}\mathrel {\longrightarrow }\mathrm {CaCO} {\vphantom {A}}_{\smash[{t]}{3}}}$ (calcium carbonate)
Basic oxide + acid	salt + water	${\mathrm {Fe} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {O} {\vphantom {A}}_{\smash[{t}]{3}}{}+{}6\,\mathrm {HNO} {\vphantom {A}}_{\smash[{t]{2}♪ I don't know what you mean ♪2\,\mathrm {Fe} (\mathrm {NO} {\vphantom {A}}_{\smash[{t]{2}}{\vphantom {A}}_{\smash[{t}]{3}}{}+{}3\,\mathrm {H} {\vphantom {A}}_{\smash[{t}]{2}$ (ferric nitrite)
metal + non-metal (of the VI or of the VII group B of the Periodic Table)	salt (not oxygenated)	${\mathrm {Zn}+{\mathrm {Cl} {\vphantom {A}}_{\smash[{t}]{2}}{\mathrel {\longrightarrow}\mathrm {ZnCl} {\vphantom {A}}_{\smash[{t]{2}}}$ (zinc chloride)
hydroxide + anhydride	salt (ternary) + water	${2\,\mathrm {NaOH}{}+{}\mathrm {SO} {\vphantom {A}}_{\smash[{t}]{2}}{\mathrel {\longrightarrow}\mathrm {Na} {\vphantom {A}}_{\smash[{t}]{2}}\mathrm {SO} {\vphantom {A}}_{\smash[{t}]{3}}{\mathrm {H} {\vphantom {A}}_{\smash[{t}]{2}$ (sodium sulfite)

NB: there are other ways to get salts starting from salts, including: salt + acid, salt + non-metal, salt + hydroxide, salt + salt.

Nomenclature

The nomenclature rules used in chemistry assign to the name salts from the ions that make them. Frequently names of cationic components, often metal ions...Explore this chapter

The nomenclature rules used in chemistry assign to the name salts from the ions that make them. Frequently names of the cationic components, often metallic ions or ammonia, are given first, followed by the names of the anionic component. Anions are often called according to their conjugated acid, replacing suffix - water with suffix -uro, the suffix -I dare with suffix -ito and the suffix -ico with suffix -ato; some examples:

vinegar salts are acetic acid salts
carbonates are salts of carbonic acid
cyanuri are salts of cyanide acid
nitrates are salts of nitric acid
nitrites are salts of nitrous acid
phosphates are salts of phosphoric acid
sulphates are sulphuric acid salts
fluorides are salts of hydrofluoric acid
chlorides are salts of hydrochloric acid
bromides are salts of bromidric acid
ioduri are salts of iodidric acid

Acid salts

In the preparation reactions of salts with acids with more than one atom of hydrogen can happen under certain conditions that to radical acid remain one or more atoms of...Explore this chapter

In the preparation reactions of salts with acids with more than one atom of hydrogen can happen under certain conditions that to radical acid remain one or more atoms of hydrogen, then by binding to metal you get an acidic salt. So a salt is acidic if it contains hydrogen residues from which it derives.

2H₂I'm sorry.₄ + 2Na → 2NaHSO₄ + H₂ (sodium acid sulphate or sodium bisulphate)

Basic salts

In the preparation reactions of salts starting from hydroxides with more than one hydroxide group under certain conditions it can happen that from hydroxide do not all stem...Explore this chapter

In the preparation reactions of salts starting from hydroxides with more than one hydroxide group under certain conditions it can happen that by hydroxide there are not all the aforementioned groups and one (or more than one) remains tied to salt. So you have a basic salt.

Es. Ca(OH)₂ + HCl → Ca(OH) Cl + H₂O (basic chloride or calcium hydroxychloride)

Taste of salts

Neutral inorganic salts can have two flavors: bitter or salty. If one or the other depends on the sum of diameters of the ionic species.Explore this chapter

Neutral inorganic salts can have two flavors: bitter or salty. If one or the other depends on the sum of diameters of the ionic species.^[3]

As reference is taken the potassium bromide that has an intermediate taste and the sum of ionic diameters is equal to 0.658 nm. Salts that have a value less than this sum are salty (sodium chloride has 0.556 nm); higher values (such as that of magnesium chloride, 0.850 nm) give the bitter taste.

In history

In ancient Rome, the legionaries and magistrates received an integration of salt-based pay at that time rare and precious substance. From this custom comes the...Explore this chapter

In ancient Rome, the legionaries and magistrates received an integration of salt-based pay, at that time rare and precious substance. From this custom comes the Italian word "salario" (in Latin) salary), with reference to the payment in rooms for the hours worked during the day.^[4]

Notes

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^ The electrical neutrality of the salt corresponds to the condition for which is nothing the algebraic sum of the charges associated with all ions of which the salt is composed.
^ The International Union of Pure and Applied Chemistry IUPAC - jumps (S05447), up goldbook.iupac.org. Retrieved 28 August 2022.
^ P.T. Coultate, Food chemistry, Zanichelli, page 209
^ Salary, up treccani.it. Retrieved 5 October 2021.