Salt in our life...

When acids and bases react with each other, they can form a salt and water. This is called a neutralization reaction and takes the following form:
HA + BOH --> BA + H2O

In chemistry, salt is a general term used for ionic compounds composed of cations (positively charged ions) and anions (negative ions), so that the product is neutral and without a net charge. These ions can be inorganic (Cl-) as well as organic (CH3-COO-) and monoatomic (F-) as well as polyatomic ions (SO42-).

Zwitterions are salts,which contain an anionic center and a cationic center in the same molecule, examples are the amino acids, many metabolites, peptides, and proteins.

The reverse of the neutralization reaction is called hydrolysis. In a hydrolysis reaction a salt reacts with water to yield the acid or base:
BA + H2O --> HA + BOH

Properties of salts

1. High melting point
Salts are usually solid crystals with a relatively high melting point. However, there exist salts that are liquid at room temperature, so-called ionic liquids. Inorganic salts usually have a low hardness and a low compressibility, similar to table salt.

2. Solubility
Salts are mostly soluble in water. During the salvation or hydration process the packed ions are separated by water molecules. However, there is some salts are insoluble in water, e.g. silver chloride, calcium sulfate, and many metal sulfides.

3.Odor
Pure salts are usually odorless, while impure salts may smell after the acid (e.g. acetates like acetic acid (vinegar), or the base (e.g. ammonium salts like ammonia).

4.Colour
Salts can be clear and transparet(e.g.sodium chloride), opaque (e.g.titanium dioxide), and even metallic and lustrous (e.g.iron disulfide). However,there are salts that exist in different colors, e.g. yellow (sodium chromate), orange (sodium dichromate), red (mercury sulfide), mauve (cobalt dichloride hexahydrate), blue (copper sulfate pentahydrate, ferric hexacyanoferrate), green (nickel oxide), colorless (magnesium sulfate), white (titanium dioxide), and black (manganese dioxide). Most minerals and inorganic pigments as well as many synthetic organic dyes are salts.

5.Nomenclature

The name of a salt starts with the name of the cation (e.g. sodium or ammonium) followed by the name of the anion (e.g. chloride or acetate). Salts are often referred to only by the name of the cation (e.g. sodium salt or ammonium salt) or by the name of the anion (e.g. chloride or acetate).

Common salt-forming cations are:
~ammonium NH4+
~calcium Ca2+
~iron Fe2+ and Fe3+
~magnesium Mg2+
~potassium K+
~pyridinium C5H5NH+
~quaternary ammonium NR4+
~sodium Na+

Common salt-forming anions (and the name of the parent acids in parentheses) are:
~acetate CH3-COO- (acetic acid)
~carbonate CO32- (carbonic acid)
~chloride Cl- (hydrochloric acid)
~citrate HO-C(COO-)(CH2-COO-)2 (citric acid)
~cyanide C≡N- (hydrogen cyanide)
~hydroxide OH- (water)
~nitrate NO3- (nitric acid)
~nitrite NO2- (nitrous acid)
~oxide O2- (water)
~phosphate PO43- (phosphoric acid)
~sulfate SO42- (sulfuric acid)

Uses of salts(examples)
~ammonium chloride(NH4Cl) use in soldering, as electrolyte in dry cells ~sodium bicarbonate(NaHCO3) use in baking powder and manufacture of glass
~sodium chloride(NaCl) use for seasoning and preserving food, essential in life processes ~calcium chloride(CaCl2) use as a drying agent to absorb moisture, in freezing mixtures
~silver bromide(AgBr) use in making photographic film ~potassium nitrate(KNO3) use in manufacture of explosives and fertilizer ~sodium nitrate(NaNO3 ) use as fertilizer and a source of nitric acid