Chemical properties of salts and methods for their preparation

Salts are substances belonging to the class of inorganic compounds, which consist of an anion (acid residue) and a cation (metal atom). In most cases, these are crystalline substances of various colors and with different solubilities in water. The simplest representative of this class of compounds is sodium chloride (NaCl).

Salts are divided into sour, normal and basic.

Normal (average) are formed in cases when in an acid all the hydrogen atoms are replaced by metal atoms or when all the hydroxyl groups of the base are replaced by acidic acid residues (for example, MgSO4, Mg (CH3COO) 2). During electrolytic dissociation, they decompose into positively charged metal anions and negatively charged acid residues.

Chemical properties of salts of this group:

• decompose when exposed to high temperatures;

• undergo hydrolysis (interaction with water);

• enter into an exchange reaction with acids, other salts and bases. It should be remembered some features of these reactions:

- the reaction with the acid passes only when this acid is stronger than that from which the salt occurs;

- the reaction with the base passes in the case when an insoluble substance is formed;

- the salt solution reacts with the metal if it is in the electrochemical stress range to the left of the metal that is part of the salt;

- Saline compounds in solutions interact with each other, if an insoluble exchange product is formed;

• Redox, which can be related to the properties of a cation or anion.

Acidic salts are obtained in cases where only part of the hydrogen atoms in the acid are replaced by metal atoms (for example, NaHSO4, CaHPO4). During electrolytic dissociation they form hydrogen and metal cations, anions of acid residue, therefore the chemical properties of salts of this group include the following features of both salt and acid compounds:

• are thermally decomposed to form an average salt;

• interact with alkali, forming a normal salt.

Basic salts are obtained in cases where only part of the hydroxyl groups of the bases are replaced by acidic acid residues (for example, Cu (OH) or Cl, Fe (OH) CO3). Such compounds dissociate into metal cations and anions of hydroxyl and acid residue. The chemical properties of the salts of this group include the characteristic chemical features of both salt substances and bases simultaneously:

• Characteristic thermal decomposition;

• interact with acid.

There is also the concept of complex and double salts.

Complex contains a complex anion or cation. The chemical properties of salts of this type include the reactions of the destruction of complexes, accompanied by the formation of sparingly soluble compounds. In addition, they are able to exchange ligands between the inner and outer spheres.

The double ones have two different cations and can react with alkali solutions (the reduction reaction).

Methods of obtaining salts

These substances can be obtained by the following methods:

• the interaction of acids with metals that are able to displace hydrogen atoms;

• Reaction of bases and acids, when hydroxyl groups of bases are exchanged with acidic acid residues;

• the effect of acids on amphoteric and basic oxides, salts or metals;

• the action of bases on acid oxides;

• reaction between acidic and basic oxides;

• interaction of salts with each other or with metals (substitution reaction) ;

• the preparation of salts in the reactions of metals with nonmetals;

• acidic salt compounds are obtained by the reaction of the middle salt with the same acid;

• basic salt substances are obtained by the interaction of salt with a small amount of alkali.

So, salts can be obtained in many ways, since they are formed as a result of many chemical reactions between various inorganic substances and compounds.