What are inorganic salts?

inorganic salts they are formed by the ionic association of at least one cation (formed by any metal or by ammonium) and an anion (simple or compound).

General molecular formula of a salt

When added to water, the salts dissociate, releasing at least one cation other than hydronium (H⁺) and an anion other than hydroxide (OH^-).

Dissociation equation for any salt

Classification of salts

Salts, in general, can have the following classifications:

• simple salt: salt formed by just one cation and one anion. Examples: NaCl, CaSO₄, KCN, NH₄CO₃ etc.

• Hydrogenated salt: it has two cations (one of which must be hydronium) and an anion. Examples: NaHCO₃, CaHBO₃ etc.

• Hydroxyl salt: it has a cation and two anions (one of which must be the hydroxide). Examples: MgOHCl, Al(OH)₂ClO₃ etc.

• Hydrated salt: presents water molecules associated with its crystalline structure. Examples: CaCl₂.2H₂O, CuSO₄.6H₂The etc.

• Double salt: it has two cations (all different from hydronium) and one anion or one cation and two anions (all different from hydroxide). Examples: Type₄CN, AgFeBO₃ etc.

• Alum: is the salt formed by two sulfates with NOx cations equal to +1 and +3, plus 24 molecules of water. Examples: Ag₂ONLY₄.Al₂(ONLY₄)₃.24H₂o, na₂ONLY₄.Sb₂(ONLY₄)₃.24H₂O

Salt naming rule

Anion name + de + cation name

→ K₃DUST₄

Salt has the phosphate anion (PO₄^-3) and the potassium cation (K⁺¹), hence its name is potassium phosphate.

→ Case₃

The salt has the sulfite anion (SO₃^-2) and the calcium cation (Ca⁺²), hence its name is calcium sulphite.

NOTE: If the cation is not silver, zinc or an element that belongs to the IA, IIA and IIIA families, we must indicate its NOX with a roman numeral in front of the cation's name.

→ Cu₂ONLY₄

The salt has the sulfate anion (SO₄^-2) and the calcium cation (Cu⁺¹), hence its name is copper sulfate I.

• Hydrogenated salt: For this salt, before the anion name, we must write the prefix referring to the amount of hydrogen in the formula. This prefix must be separate from the word hydrogen by a hyphen.

→ NaHCO₃

Salt has a hydrogen, carbonate anion and sodium cation, so its name is sodium monohydrogen carbonate.

• Hydroxyl salt: For this salt, before the anion name, we must write the prefix referring to the amount of hydroxyls in the formula. This prefix must be separate from the word hydroxy by a hyphen.

→ Al(OH)₂ClO₃

The salt has two hydroxyls, the chlorate anion and the aluminum cation, so its name is aluminum dihydroxy-chlorate.

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• Hydrated salt: For this salt, after the name of the cation, we must write the prefix referring to the amount of water molecules in the formula. This prefix must be separate from the word hydrated by a hyphen.

→ CaCl₂.2H₂O

Salt has two water molecules, the chloride anion and the calcium cation, so its name is calcium chloride dihydrate.

• Double salt with two cations: For this salt, we must write the double word in parentheses after the anion name and then the most electropositive cation name and the other cation.

→ AgFeBO₃

This salt has silver (more electropositive cation) and iron II cation, in addition to the borate anion. Its name is borate (double) of silver and iron II.

• Double salt with two anions:

  Name of most electronegative anion + hyphen + name of least electronegative anion + de + cation name

→ Type₄CN

This salt contains the titanium IV cation, in addition to the phosphate (more electronegative anion) and the cyanide anion. Its name is titanium cyanide phosphate IV.

• Alum salt: For this salt, we ignore the general rule. Just write the term alum followed by the +3 charge cation name and the +1 charge cation name, respectively, separated by the conjunction e.

→ In₂ONLY₄.Sb₂(ONLY₄)₃.24H₂O

The alum salt has the +3 antimony cation and the +1 sodium cation, so its name is antimony III alum and sodium.

Physical characteristics of salts

• They are solid at room temperature;

• They have high melting and boiling points;

• They are formed from ionic bonds;

• They conduct an electric current in the liquid state (after undergoing fusion) or when dissolved in water;

• Generally speaking, they are soluble in water, but there are salts that are considered practically insoluble.

Chemical properties of salts

Salts are compounds that have the ability to chemically react (provided they do not have the same cation or the same anion as another substance) with several groups of substances, namely:

• In a double exchange reaction with an acid: they form a new salt and a new acid.

• In a double exchange reaction with a base: they form a new salt and a new base.

• In a double exchange reaction with another salt: form two new salts.

Some salts have the ability to suffer decomposition when subjected to heat, forming two or more new substances. If we heat the sodium bicarbonate (NaHCO₃), for example, it will decompose, forming sodium carbonate (Na₂CO₃), water (H₂O) and carbon dioxide (CO₂).

By Me. Diogo Lopes Dias

Would you like to reference this text in a school or academic work? Look:

DAYS, Diogo Lopes. "What are inorganic salts?"; Brazil School. Available in: https://brasilescola.uol.com.br/o-que-e/quimica/o-que-sao-sais-inorganicos.htm. Accessed on June 28, 2021.