✪Salt in our daily life

Salt is a dietary mineral that contain sodium chloride that is essential for human life. It is a white crystalline solid, normally obtained from sea water or rock deposits. We use salt (table salt) as flavoring when we cuisine, salt make dish more delicious. Some people also use salt as preservative when they bloat meat, fish, vegetable and other food.

The main components of salt are chloride and sodium ions. Crystal of NaCl form cubical symmetry. In its crystal structure, chloride ion arranges becomes the cubic closest packing and sodium ion fills between the chloride ion octahedron interstice .Each ion is surrounded by six other ions. This kind of structure also exists in many other compounds, called sodium chloride structure or halite structure.

Character of NaCl:

· Outward appearance and shape: white crystal

· Alkalinity: 18.2-21.0

· Relative densities: 2.165(25℃)

· Melting point (℃): 801 ℃

· Boiling point (℃): 1413 ℃

· Solubility: different temperature, different solubility

Solubility of NaCl in various solvents(g NaCl / 100 g of solvent at 25 °C)
H2O	36
Liquid ammonia	3.02
Methanol	1.4
Formic acid	5.2
Acetone	0.000042
Acetonitrile	0.0003
Dimethylformamide	0.04

· Dissolves in the water and the glycerin, difficult to dissolve in the grain alcohol.

Salt can be classify as unrefined salt (such as sea salt), refined salt (table salt, and iodized salt. Different salts have different mineral ties. Some scholar asserts that unrefined salt is healthier than refined salts. Whereas, unrefined salt is rarely eaten as it is bitter because of magnesium and calcium compounds. It also does not contain enough iodine salts to prevent iodine deficiency diseases. Iodine deficiency leads to thyroid gland problem, usually resulting in a bulbous protrusion on the neck. A refined salt like iodized salt is table salt mixed with little potassium iodine, sodium iodide, or sodium iodated. Iodine salt can prevent the shortage production of thyroid hormones. Shortage thyroid hormones shall cause illness similarity cretinism in children and myxedema in adults.

Chloride and sodium ions are necessary for the survival of all known living creatures. Salt is involved in regulating the water content (fluid balance) of the body. Whereas，over consumption of salt increases the risk health problems.

Salt is important to normal body but too much will bring disadvantage.

Therefore, we must control amount of salt when we ingests it. One way to control sodium intake is to read label and then buy food with less salt. Also, we can control the amount of salt that we add while cooking. When we cook, limit sauce. It was because sauce usually provided with high sodium levels.