The sodium chloride, Also called common salt or table salt, it is a binary inorganic salt of the alkali metal sodium and the halogen chlorine. It is the largest component of edible salt and its mineral form is known as halite. Its molecular formula is NaCl, and it describes the stoichiometric ratio of its ions (Na+ Cl-) and not that of a discrete molecule (Na-Cl)
Sodium chloride is a white crystalline solid that is formed by the combination of sodium, a silvery white metal, which reacts violently with water, and the element chlorine, a poisonous, corrosive and pale green gas..
A portion of NaCl crystals is shown in the upper image. How is it possible that two elements as dangerous as Na and Cltwo, an edible salt can be formed? First, the chemical equation for its formation is:
2Na (s) + Cltwo(g) => 2NaCl (s)
The answer lies in the nature of the bond in NaCl. Being ionic, the properties of Na+ and Cl- are diagonally different from their neutral atoms.
Sodium is a vital element, but in its ionic form. The Na+ is the main extracellular cation with a concentration of approximately 140 mEq / l, and together with its accompanying anions, Cl- and the HCO3- (bicarbonate), are mainly responsible for the value of osmolarity and extracellular volume.
Furthermore, the Na+ it is responsible for the generation and conduction of the nerve impulse in the neuronal axons, as well as for initiating muscle contraction.
NaCl has been used since ancient times to flavor food and to preserve meat, due to its ability to kill bacteria and prevent spoilage..
It is also necessary for the production of sodium hydroxide (NaOH) and molecular chlorine (Cltwo), reacting NaCl with water under hydrolysis:
2HtwoO (l) + 2 NaCl (s) => 2NaOH (aq) + Cltwo(g) + Htwo(g)
In the cathode (-) accumulate the Htwo (g) and NaOH. Meanwhile, in the anode (+) the Cl accumulatestwo (g). Sodium hydroxide is used in the manufacture of soaps and chlorine in the manufacture of PVC plastic.
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The upper image represents the compact cubic structure of sodium chloride. The voluminous green spheres correspond to the Cl anions-, while the white ones, to the Na cations+. Note how the NaCl crystal consists of a network of ions arranged by their electrostatic interactions in a 1: 1 ratio..
Although bars are shown in the image, the bonds are not covalent but ionic. The use of bars is useful when showing the coordination geometry around an ion. For example, in the case of NaCl each Na+ is surrounded by six Cl- (white octahedron), and each Cl- of six Na+ (green octahedron).
Therefore, it has a coordination (6,6) whose numbers indicate how many neighbors surround each ion. The number on the right indicates the neighbors of the Na+, while the one on the left, those of the Cl-.
Other representations omit the use of bars to highlight the octahedral holes in the structure, which result from the interstitial space between six Cl anions.- (or Na cations+) packaged. This arrangement is observed in other mono (MX) or polyatomic inorganic salts, and is called the gem salt.
The unit cell of rock salt is cubic, but which cubes exactly represent it in the image above? The octahedrons give the answer. Both cover a total cell made up of four small cubes.
These cubes have portions of the ions at their vertices, edges, and faces. Looking closely, a Na ion+ it is located in the center and twelve of them on the edges. An ion on an edge can be shared by four cubes. So there are 4 Na ions+ (12 × 1/4 + 1 = 4).
For Cl ions-, eight are located at the vertices and six at the edges. As the ions positioned at the vertices share space with eight other cubes, and at the edges with six, we have 4 Cl ions- (8 × 1/8 + 6 × 1/2 = 4).
The above result is interpreted as follows: in the unit cell of NaCl there are four Na cations+ and four Cl anions-; proportion that agrees with the chemical formula (a Na+ for each Cl-).
NaCl.
58.44 g / mol.
A crystalline solid.
Transparent colorless crystals or white crystalline powder.
Salty.
2,575ºF to 760 mmHg.
1,465 ºC.
1,474 ºF (800.7 ºC).
Both the boiling point and the melting point reflect the heat necessary to overcome the crystalline lattice energy. Therefore, these measurements confirm the ionic character of NaCl..
Greater than or equal to 100 mg / ml at 68ºF.
36.0 g / 100 ml at 25 ° C.
It is in fact a hygroscopic salt, which retains moisture from the environment.
0.065 g / 100 mL of ethanol at 25 ° C; 10 g / 100 g of glycerol at 25 ° C; 2.15 g / 100 mL of liquid ammonia at 40 ° C; 1.4 g / 100 mL of methanol at 25 ° C; 7.15 g / 100 of ethylene glycol at 25 ° C and 5.21 g / 100 g of formic acid at 25 ° C.
2.165 g / cm3 at 77 ºC.
1 mmHg at 1,589ºF.
Stable under recommended storage conditions.
When heated to high temperatures, it decomposes, emitting hydrochloric acid and disodium oxide vapors..
Viscosity of saturated solutions 1.93 mPa-s.
It is corrosive to many metals.
6.7 to 7.3 in aqueous solution.
-Sodium chloride has been used since ancient times to improve the taste of food and to preserve it. Salting meat is a way to preserve it from bacterial action, as it delays protein breakdown.
-On the other hand, salt increases the osmolarity around the meat, which causes the absorption by osmosis of the water of the bacteria, causing their elimination..
-In the food industry, salt is used as a flavor enhancer, fermentation control additive, texture control agent, and color developer. For example, salt is added to bring out the color in bacon, ham, and other meat products..
-Salt serves as a binder in making sausages. Contributes to the formation of a binder gel composed of meat, fat and moisture.
-In flour processing for bread making, salt is added during baking to control the rate of leavening of bread dough. It is also used to strengthen gluten and as a flavor enhancer, as well as a filling in baked goods.
-It is used in the manufacture of breakfast cereals, mixed or prepared flours, French fries, dog and cat foods, etc..
-Sodium chloride is used as a raw material in the production of sodium hydroxide and chlorine, which, in turn, are useful in many chemical industries.
-Salt is used in the processing of various metals, for example aluminum, copper, steel, and vanadium. It is also used to make sodium chlorate, which is later used in the synthesis of chlorine dioxide, an oxygen-based bleach. Chlorine dioxide is less harmful to the environment than other bleaches.
-The salt is used to inhibit the bacterial action inside the skin, as well as to help in its rehydration.
-Salt is used as a mordant in the dyeing of fabrics. It is used as a brine rinse to remove organic contaminants and to create a positive charge on the surface of fabrics that allows negatively charged dyes to bind.
-In oil and gas exploration, salt is an important component of well drilling fluids. It is used to flocculate and increase the density of drilling liquids, which allows to overcome the high gas pressures in the wells to be reached. In addition, the salt maintains the saturation of the drilling liquid.
-Salt helps compact the soil on which roads are built. Reduces underground displacement caused by humidity changes and automotive traffic.
Salt has been used by rubbing in cleaning surfaces, pots and pans. Also in the prevention of mold and as a stain remover. It is also used in many brands of shampoo and toothpaste..
-In anticipation of snowfall, roads are covered with brine, which prevents ice from binding to the road surface. For thawing, a mixture of brine and salt is used, and sometimes other chemical components such as magnesium or calcium chloride are added. The use of salt and brine is not effective at temperatures below -10 ºC.
When adding salt, a decrease in the cryoscopic point is produced, a colligative property of the solutions, thus hindering the formation of ice in a certain way..
-Due to its hygroscopic condition, salt is used as a cheap desiccant.
Hard water contains calcium and magnesium ions that hinder the action of soap and produce alkaline material deposits on various equipment and pipes. In water softening, ion exchange resins are used. Salt is used in the preparation and regeneration of resins.
Sodium chloride is used in fire extinguishers to fight fires in which combustible metals are present, such as magnesium, potassium, sodium, and NK alloys..
Salt acts as a heat sink and also forms a crust that restricts oxygen access to the fire..
Sodium chloride crystals are used in optical components such as windows and prisms, especially for infrared light. However, since the salt is very hygroscopic, a kind of frost is produced that covers the lenses. For this reason, sodium chloride lenses have been replaced by zinc selenide (ZnSe) lenses..
-When there is a bodily depletion of Na+, must be replaced to maintain extracellular osmolarity, nerve conduction, and muscle contraction.
-NaCl is used in the treatment and prevention of sodium and chlorine deficiency, resulting from excessive sweating during exposure to high temperatures. It is also used in an excessive diuresis or an excessive restriction of saline intake.
-Parenteral delivery of a 045% NaCl solution is used in the management of hyperosmolar diabetes. It fulfills a rehydrating function and is used to assess the status of kidney function.
-Injections of hypertonic solutions, with a NaCl concentration greater than 0.9% w / v,
-They are used when there is a severe Na depletion+, being a restoration of the essential ion. This hyponatremia can be the consequence of a treatment with free electrolytes or with a concentration of Na+.
Hyponatremia can also be caused by excessive water intake, not controlled by inadequate kidney function..
-NaCl inhalation solutions are used to dilute the drugs used during the nebulization process. It is also used for tracheal lavage and irrigation. 0.9% saline solution used in nasal sprays.
-20% NaCl solutions are used for its intra-amniotic transabdominal installation, thereby inducing a late abortion during the second trimester of pregnancy..
-Sodium chloride can be used as a local antiseptic. Thanks to its osmotic capacity, it is capable of dehydrating a wide spectrum of viruses and bacteria in a non-spurated state; therefore, it is used as a painful antiseptic to disinfect wounds.
It only has a harmful effect on health if the intake is high and for a long time. Under these circumstances, hypernatremia would occur with the consequent increase in extracellular volume that would lead to arterial hypertension..
It has a toxic effect only if the inhalation is very high. Excessive contact with the skin can cause it to be dry. Finally, it causes a momentary irritation on contact with the eyes.
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