Sodium chloride (table salt)

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O sodium chloride (table salt) is the salt we use in our daily lives to salt handcrafted or processed (industrialized) foods. It is a substance that is also present in various natural foods consumed by us on a daily basis, such as fruits, vegetables, legumes, seeds, etc.

In this text you will know everything about this important substance for the human being's daily life:

the definition

Sodium chloride belongs to the inorganic function of salts and is composed by the association of the sodium cation (Na+) it's the anion cthereoreto (Cl-) through a ionic bond.

b) Chemical characteristics

Sodium chloride is formed by two chemical elements:

→ Sodium (Na):

  • belongs to the family of metals (capable of forming cations easily) alkaline (AI);

  • has an electron in the valence shell;

  • has atomic number equal to 11;

  • has high electropositivity (ability to lose electrons).

→ Chlorine (Cl)

  • belongs to the family of halogens (VIIA);

  • it's a nonmetal (that's why it becomes an anion so easily);

  • has seven electrons in the valence shell;

  • has atomic number equal to 17;

  • has high electronegativity (ability to gain electrons).

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As the two chemical elements that form sodium chloride present, respectively, high electropositivity and high electronegativity, between them there is an ionic bond (established between atoms with a tendency to lose and gain electrons).

The chemical structure of sodium chloride is composed of a single chloride anion (green sphere), which interacts with six sodium cations (blue spheres), as can be seen in the structure below:

Representation of the crystal structure of sodium chloride
Representation of the crystal structure of sodium chloride

c) Physical characteristics

  • Fusion point:

Sodium chloride can be transformed from solid state to liquid state at a temperature of 801 OÇ.

  • Boiling point:

Sodium chloride can be transformed from a liquid to a gaseous state at a temperature of 1465 OÇ.

  • Polarity

As it is a substance originated by an ionic bond, that is, because it is an ionic compound, sodium chloride is polar.

  • Solubility in water

We can dissolve in 1 L of water, at 25 OC, up to 359 grams of sodium chloride.

  • Solubility in other solvents:

As sodium chloride is a polar compound, it cannot be dissolved in any solvent of a non-polar nature, such as oil.

  • Density:

The density of sodium chloride is 2.165 g/mL, therefore, it is denser than water, which has a density equal to 1 g/mL.

  • Electrical conductivity:

As it is an ionic compound, sodium chloride is capable of conducting an electric current only when:

  • It is in its molten state, that is, liquid;

  • Dissolved in water.

d) Methods of obtaining

Sodium chloride can be obtained physically or chemically:

1O) Getting physical:

  • fractional crystallization

Sodium chloride is obtained by evaporating water from oceans.

  • underground mines

It is extracted in mines using mining techniques.

  • underground deposits

It is extracted from deep underground deposits by dissolving in water (the salt present in the deposit dissolves) and subsequently pumping.

2O) Obtaining chemically

  • synthesis reaction

Sodium chloride can be obtained from the chemical reaction of synthesis (simple substances give rise to a compound substance) between chlorine gas and metallic sodium:

2 In(s) + Cl2(g) → 2 NaCl(s)

  • Neutralization reaction:

Another way to obtain sodium chloride chemically is through the neutralization reaction between hydrochloric acid and sodium hydroxide, in which we have the formation of salt and water:

HCl(1) + NaOH(here) → NaCl(here) + H2O(1)

e) Importance for human beings

Sodium chloride by itself has no function in the human body, but when it dissociates into sodium cations (Na+) and chloride anions (Cl-), each of these two ions has several important functions for our body. See some of these functions:

→ Functions of the sodium cation (Na+)

  • Prevents blood clotting;

  • Fights the formation of kidney and gallstones;

  • Participates in the regulation of body fluids;

  • Participates in the regulation of blood pressure.

→ Functions of the chloride anion (Cl-)

  • Participation in the formation and constitution of gastric juice (hydrochloric acid – HCl);

  • Participation in the formation of pancreatic juice.

f) Damage to the human body

Excessive consumption of sodium chloride can cause the following harm to humans:

→ Damage caused by excess sodium cations in the body:

  • Increased wound healing time;

  • Increased incidence of cramps;

  • Increased blood pressure;

  • Kidney overload;

  • Increased fluid retention in the body.

→ Damage caused by excess chloride anions in the body:

  • destruction of vitamin E;

  • Decrease in iodine production in the body.

g) Other applications

In addition to being used to salt food, sodium chloride can also be used in the following situations:

  • Shampoo production;

  • Paper production;

  • Production of Sodium hydroxide (NaOH);

  • Detergent production;

  • Soap production;

  • Snow melting in places that suffer from blizzards;

  • Production of metallic sodium;

  • Chlorine gas production;

  • In isotonics for body electrolyte replacement;

  • In nasal decongestant solutions;

  • Production of saline solution; among other applications.

By Me. Diogo Lopes Dias

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