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We explain what salts are, the properties they have and how they are classified. Also, what are its characteristics and some examples.

What are salts?

Salts are called chemical compounds that are the result of an ionic bond between chemical particles with a positive charge (cations) and others with a negative charge (anions). They are the typical result of the chemical reaction between an acid and a base, also known as a neutralization reaction.

There are different types of salts, depending on their chemical composition, their usefulness for human industries and their nomenclature. The best known is perhaps sodium chloride (NaCl).which is common salt or table salt, used in cooking.

Physical properties of salts

The properties of salts They can be very varieddepending on its composition.

Generally speaking, they are crystalline compounds with an ionic structure.
Their structure gives them high melting points and dielectric (insulating) properties in the solid state.
Many are soluble in water and salt solutions conduct electric current.
They usually have different colors (from the white of common salt to red, black, blue and mauve, depending on their components). Their flavors range from salty, sweet, sour and bitter. They give off little or no odor.

Chemical properties of salts

Types of salts according to their composition

Salts can be classified according to the quantity and type of ions (H+ and OH-) that compose them:

Basic salts or hydroxysaltsThey are formed when in a neutralization reaction the hydroxide is in excess with respect to the acid. The solutions of these salts have a basic pH. For example: basic magnesium nitrate (MgNO3OH) and basic mercury nitrite (HgNO2OH).
acid salts. They are formed when the hydrogen (not all the hydrogens, but at least one of them) in an acid is partially replaced by a metal cation. Solutions of these salts have an acidic pH. For example: lithium bicarbonate (LiHCO3), in this case a hydrogen of the carbonic acid (H2CO3) was replaced by the lithium cation.
Neutral salts. They are the product of the total neutralization of an acid and a base, and lack H+ and OH- ions. In this case, all the hydrogen atoms of an acid are replaced by a metal cation. For example: sodium chloride (NaCl), in this case the hydrogen of hydrochloric acid (HCl) was replaced by the sodium cation.
mixed salts. They are composed of two cations or two different anions. For example: potassium calcium phosphate (KCaPO4).
Hydrated salts. They are salts in whose crystalline composition water molecules appear. For example: sodium sulfate decahydrate (Na2SO4 * 10H2O).

Classification of salts by their quantity of elements

Another way of classifying salts is based on the number of elements present in their formula, as follows:

Binary salts. They present two elements: a metal and a non-metal. For example: sodium chloride (NaCl).
Ternary salts. They present three elements: a metal, a non-metal and oxygen. For example: lead(II) selenite (PbSeO3).
Quaternary salts. They present four different elements, between metals and non-metals. For example: sodium bicarbonate (NaHCO3).

How are salts formed?

Nomenclature of salts

The salts are named as follows:

binary saltsThey are named by writing the name of the non-metal with the suffix -ide, followed by the preposition ‘of’, followed by the name of the metal. If the metal has more than one oxidation number, this number is written in Roman numerals and in parentheses at the end. For example: sodium chloride (NaCl), iron (II) chloride (FeCl2) and iron (III) chloride (FeCl3).
Oxacid salts.
- Stock Nomenclature. They are named by writing the name of the ion, followed by the preposition ‘de’, followed by the name of the metal. If the metal has more than one oxidation number, this number is put in Roman numerals and in parentheses at the end. For example: magnesium sulfate (MgSO4), calcium carbonate (CaCO3) and iron (II) nitrate (Fe(NO3)2).
- Traditional Nomenclature. It starts from the completion of the acid from which the salt comes. If the name of the acid ends in ‘-oso’, the name of the anion of the salt is given with the suffix ‘ito’, and if it ends in ‘ico’, it is given ‘-ato’.
  On the other hand, the ending of the name of the metal will depend on the number of oxidation numbers it has. If it has two oxidation numbers, the one with the lowest oxidation number ends in ‘-oso’ and the one with the highest oxidation number ends in ‘-ico’.
  For example: in magnesium sulfate (MgSO4), the sulfate ion (-ate) comes from sulfuric acid (H2SO4) (-ic). In ferrous sulfate (Fe(SO4)2) iron has oxidation number 2+ and in ferric sulfate (Fe(SO4)3) it has 3+.
acid salts. They are named indicating the number of unsubstituted hydrogens in the molecule, using the corresponding prefix. For example, the NaHS salt is called sodium hydrogen sulfide, since the HS- anion comes from hydrogen sulfide (H2S). Lithium hydrogen carbonate (LiHCO3), whose anion comes from carbonic acid (H2CO3).
Basic salts. They are named indicating the number of hydroxyls followed by the central anion and finally the metal cation. For example, MgCl(OH) is called magnesium hydroxychloride or it can also be named as basic magnesium chloride.
Hydrated salts. They are named by indicating the name of the corresponding salt followed by the prefix corresponding to the quantity of water molecules, followed by the word ‘hydrated’. For example: MgSO4 * 5H2O is called magnesium sulphate pentahydrate.

Where are salts found?

Salts can be found as part of underground and rock minerals, such as halite, or also dissolved in water, such as in oceans and seas. These are abundant and necessary compounds for organic life as we know it, so they are not difficult to acquire through food.

Biological importance of salts

Salts are part of numerous organic compounds. Furthermore, they occupy a central place in biological processes such as:

Muscle contraction.
Transmission of nervous impulses.
Chlorophyll synthesis.
Transport of oxygen in hemoglobin.
Functioning of enzymes.
Generation of insoluble solid structures such as bones, shells, etc.

What are salts used for?

Salts have different uses in human industries. In gastronomy they are used as ingredients (as is the case with common salt or baking soda). In the pharmaceutical industry they are used as laxatives and bases for medical supplies.

Its industrial use is widespread. For example, they are the base of fire extinguishers and various construction materials. They can also be desiccants and fertilizers. Some more specific salts are used to make explosives or for the photographic industry.

Mineral salts

Mineral salts are ionic compounds, of entirely inorganic origin (hence the name “mineral”). However, they can also be found in the body of living beings, which must consume them through food since they carry out various functions of regulation, metabolism and nervous excitability.

They are particularly abundant on our planet, are part of subsoil minerals or dissolved in marine waters. In principle, they are not distinguishable from organic salts, except for the type of elements present in their molecular constitution.

Examples of salts

Some commonly used salts are the following:

Sodium Nitrate (NaNO3)It is used for the treatment of botulism (a disease caused by neurotoxins of bacterial origin).
Sodium Nitrite (NaNO2)It is used in the food industry as a preservative and also as a color fixative.
Lithium bicarbonate (LiHCO3). It is used as a CO2 capture agent in space missions.
Sodium hydrogen sulfide (NaHS). It is a dangerous salt that requires delicate handling, is highly corrosive, combustible and toxic.
Dicalcium phosphate (CaHPO4). Known as calcium monohydrogen phosphate, it is used as an additive in foods and toothpastes.

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