In chemistry, a salt is described as a chemical compound that consists of an ionic assembly of cations and anions. In general, salts are composed of related numbers of cations (which are positively charged ions) and anions (which are negatively charged ions) so that the product is defined as electrically neutral (without any net charge). These component ions are organic, such as acetate (CH3CO−2) are inorganic, such as chloride (Cl−); and can be monatomic, such as polyatomic or fluoride (F−), such as sulfate (SO2−4).
Examples of salt are given as CuCl2, NaCl, and more.
Acid + Base → Salt + water
Sodium chloride is the best-known salt, and one salt is referred to by almost everyone due to its widespread use every day.
Types of Salts
Let us look at different types of salt as listed below.
Acidic Salt - The salt that is formed by the partial neutralization of a polyprotic or diprotic acid is called acidic salt. These salts contain ionizable H+ ions along with another cation. Mostly the ionizable H+ comes under the part of an anion. A few acid salts can be used in baking.
For example, KH2PO4, NaHSO4, and more.
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H2SO4 + NaOH → NaHSO4 + H2O
Alkali or Basic Salt - The salt that is formed by the partial neutralization of a strong base by the weak acid is called a basic salt. These salts hydrolyze to produce a basic solution. This happens because when the hydrolysis of a basic salt occurs, the conjugate base of the weak acid is produced in the solution.
For example, White lead (2PbCO3·Pb(OH)2).
Double Salt - The salts which contain more than one cation or one anion are called double salt. These salts are obtained by the combination of two different salts that are crystallized in a similar ionic lattice.
For example, Potassium sodium tartrate (KNaC4H4O6.4H2O) is also called Rochelle salt.
Mixed Salts - The salt which holds a fixed proportion of two salts and often shares either a common cation or anion is called mixed salt.
For example, CaOCl2.
Properties of Salt
Solid salts tend to be transparent, as represented by the sodium chloride compound. In most cases, the apparent transparency or opacity is only related to the difference in the size of the individual monocrystals. Since the light reflects from the grain boundaries (boundaries between the crystallites), the larger crystals tend to be as transparent, while the polycrystalline aggregates seem to be as white powders.
Salts of both strong acids and strong bases ("which are referred to as strong salts") are non-volatile and often odourless, whereas the salts of either weak acids or weak bases ("which are referred to as weak salts") can smell as the conjugate acid (for example, vinegar and almonds) or the conjugate base (for example, ammonium salts such as ammonia) of the component ions.
Various salts can elicit all 5 basic tastes, for example, sweet (lead diacetate, which causes lead poisoning when ingested), salty (sodium chloride), bitter (magnesium sulfate), sour (potassium bitartrate), and savoury (monosodium glutamate) or umami.
Characteristically, salts are insulators. Molten salts or salt solutions conduct electricity. Due to this reason, liquified (molten) salts and the solutions consisting of dissolved salts (for example, sodium chloride in water) are referred to as electrolytes.
Characteristically, salts contain high melting points. Suppose, sodium chloride melts at a temperature of 801 °C. A few salts having low lattice energies are liquid near or at room temperature. These are the molten salts, which are usually mixtures of ionic liquids, and salts, which usually hold organic cations. These liquids represent unusual properties like solvents.
Identification of Salts
By definition, if a compound is produced of either a cation and an anion, it is described as salt in chemistry.
The simplest salts are the compounds of a kind of metal cation having one kind of non-metal anion. If we look at the periodic chart, there is a dark and stair-step line over on the right. The atoms that exist to the left of it are said to be metals, and those to the right are said to be non-metals, and a few of those present on the steps (not aluminium) are called metalloids or semi-metals.
Compounds that hold a metal cation and a polyatomic anion are also called salts. At the same time, compounds that hold a polyatomic cation and an anion are also called salts.
Differentiation Between Acidic and Basic Salt
A basic salt holds the weak acid's conjugate base. Hence, acetate is described as the conjugate base of a weak acid's acetic acid. Thus, sodium acetate is basic.
An acidic salt contains the weak base's conjugate acid. Hence, ammonium ion is described as the weak base ammonia's conjugate acid. Thus, ammonium chloride would be the acidic salt.
The conjugate bases of strong acids (Cl- from HCl) and the conjugate acids from strong bases (Na+ from NaOH) are given as neutral and produce neutral salts such as NaCl.