Sulphur: obtaining, properties, uses and characteristics

We explain what sulfur is, where it is found, and how this mineral is obtained. In addition, its characteristics, properties, uses, and more.

Sulfur is yellow in color and is insoluble in water.

What is sulfur?

Sulfur is a chemical element, classified within the group of non-metals, which is found abundantly in nature. It has a characteristic rotten egg odor, it comes in a strong lemon yellow, brownish or orange color. It is insoluble in water but soluble in carbon disulfide (CS ₂ ), and burns with a blue flame emitting sulfur dioxide (SO ₂ ).

Its atomic number is 16, its chemical symbol is S. It belongs to group 16, period 3, block p of the Periodic Table. Its atomic mass is 32.065(5) u, its electronic configuration [Ne] 3s ² 3p ⁴ , the electrons per level 2,8,6; it is multivalent and common oxidation states are -2, +2, +4, +6.

Origin of the word Sulfur

Etymologically it comes from the Latin sulphurium, this in turn from the Sanskrit śulbāri, a term that means “ copper loses value when joined to sulphur”. It was also called "flammable stone".

history of sulfur

Sulfur was believed to be the missing piece in the philosopher's stone for making gold.

Sulfur has been known since ancient times. In the Greek and Roman cultures, medicinal properties were attributed to it and it was used in the whitening of fabrics; the Egyptians used it for the purification of the temples.

It played a leading role in the doctrines of the ancient alchemists, who considered this element as the missing component in the philosopher's stone to be able to manufacture artificial gold.

Sulfur has been known since time immemorial, but as an element, it was discovered by Henning Brand. A merchant and amateur alchemist from Hamburg (who also discovered phosphorus (P)). However, it was the French chemist Antoine Lavoisier who, through a series of experiments carried out in 1777, discovered that sulfur is an element rather than a compound and was the first to classify it as a chemical element.

Where is sulfur found?

Sulfur can be found in underground deposits, hot springs, and volcanoes.

Free sulfur is found in volcanic deposits, hot springs, and also in underground deposits, mainly in the USA (Texas, Louisiana), Russia, Japan, Canada, France, Mexico, Poland, and Sicily.

In a combined state it appears in the form of sulfides (pyrite and galena) and sulfates (gypsum), in numerous minerals. It is also found in a wide variety of organic compounds such as animal proteins and some vegetables.

How is sulfur obtained?

Sulfur can be collected in deposits where it is found combined with volcanic ash.

Obtaining sulfur is carried out mainly through the Frash Process, a method to extract the element from the depths of the earth, melting the sulfur contained in underground deposits (it is a system similar to that of oil exploration).

Sulfur is also obtained from the separation of natural gas containing hydrogen sulfide (H ₂ S), through the oxidation process. It is also extracted from oil, from the smelting of rocks that contain it, and from manual collection in deposits of pure sulfur combined with volcanic ashes.

Characteristics of sulfur

Sulfur is a poor conductor of heat and an insulator of electricity.

• As a non-metal, it is characterized as having no shine or luster.
• It does not reflect light and, in its natural state, appears lemon yellow.
• Its consistency is solid but soft and brittle.
• It is a poor conductor of heat and an insulator of electricity.
• Its melting point is relatively low.
• It has four natural isotopes: ^32S (95.02%), ^33S (0.75%), ^34S (4.21%) and ^36S (0.02%); twenty unstable with a half-life ranging from 21 milliseconds, in addition to ³⁵ S (whose half-life is 87.32 days).

Structural forms of sulfur

Sulfur has a misshapen eight-atom ring structure.

Sulfur occurs in different forms or allotropes in the solid, liquid, and gas phases:

• Solid sulfur is made up of a molecular structure of eight-atom misshapen rings and adopts one of two crystalline forms: the orthorhombic octahedron (Sα) and the monoclinic prism (Sβ). The arrangement of the molecules determines the enunciated forms, whose transition temperature from one to another is 96 °C. At room temperature, the shape transition is slower.
• By raising the temperature, it becomes a fluid and transparent yellow liquid, which presents changes in its properties and structure. The color turns brown and thick and clears again when it reaches the boiling point, becoming a red and viscous liquid. These shape changes occur when the sulfur rings separate and break due to combustion. Cooling the viscous liquid results in a rubbery mass called plastic sulfur. Once it cools down, it crystallizes adopting the rhombic structure.
• In the gas phase at 780 °C, it adopts a balanced form of mixture with diatomic molecules. Above 1800 °C the molecular separation is complete and sulfur atoms are found.

Atomic Properties of Sulfur

• Medium radius: 100 pm
• Electronegativity: 2.58 (Pauling scale)
• Atomic radius (calc): 88 pm (Bohr radius)
• Covalent radius: 102 pm
• van der Waals radius: 180 pm
• Oxidation state(s): ±2, 4.6 (strong acid)
• 1st Ionization Energy: 999.6 kJ/mol
• 2nd Ionization Energy: 2252 kJ/mol
• 3rd Ionization Energy: 3357 kJ/mol
• 4th Ionization energy: 4556 kJ/mol
• 5th Ionization energy: 7004.3 kJ/mol
• 6th Ionization energy: 8495.8 kJ/mol

Physical Properties of Sulfur

• Ordinary State: Solid
• Density: 1960kg/ ^m3
• Melting point: 388.36K (115°C)
• Boiling point: 717.87K (445°C)
• Vaporization enthalpy: 5 kJ/mol
• Fusion enthalpy: 1.7175 kJ/mol
• Vapor pressure: 2.65 × 10 ^-20 Pa at 388 K
• Critical point: 1314 K (1041 °C) (20.7 MPa)

uses of sulfur

Sulfur is used for the manufacture of plastics, paints, among others.

Most of it goes to the production of sulfuric acid (H ₂ SO ₄ ), one of the most important chemical products, used in turn in the production of fertilizers from phosphates and ammonia.

It is also used in the vulcanization of rubber, soap making, detergents, cement, electrical insulators, plastics, explosives, bleaches, dyes, drugs, paints, paper, and oil refining.

In addition, it calms the symptoms of skin diseases, it is ideal for treating eczema and allergic skin reactions. It eliminates toxins, which is why it is often incorporated into anti-acne and anti-fat products.

Sulfur nutritional properties

Sulfur can be found in vegetables such as broccoli, cabbage, and turnips.

The consumption of foods rich in sulfur benefits health and provides nutrients to the body. Its presence is recognized by the spicy taste. Some of the foods richest in sulfur are:

• Vegetables. Broccoli, cabbage, turnip; garlic and onion; cucumber, bell pepper, eggplants; soybeans, lentils, beans; mango, grapefruit, orange, plum, pear, banana, apple; sunflower seeds, oats.
• Meats. Fish and shellfish.

Sulfur Cycle

Sulfur circulates through the biosphere in the following ways:

• From soil, air, or water to plants by absorption.
• From plants to animals by ingestion.
• The atmosphere arrives in the form of gases emitted by the decomposition of organic matter (hydrogen sulfide – H ₂ S and sulfur dioxide – SO ₂ ) or volcanoes.
• It returns to the soil and water by deposition, rain or decomposition of living beings and by penetration of the atmosphere by gases.
• Acid rain: the SO ₂ accumulated in the atmosphere can combine with another oxygen atom forming sulfur trioxide (SO ₃ ) which, in contact with atmospheric humidity, becomes sulfuric acid (H ₂ SO ₄ ), harmful to life. It precipitates to the surface in the form of “acid rain”. To combat acid rain, it is necessary to reduce polluting gas emissions, save energy and reduce the consumption of fossil fuels that contain sulfur.

World production and reserves of sulfur

The world's leading producer of sulfur is the United States.

The natural reserves of sulfur are 5,000 million tons. Half of the sulfur used in industry is obtained by desulfurizing natural gas and oil, converting sulfur compounds into hydrogen sulfide. Recovery from nature reserves is expensive and there are more regulations on environmental contamination.

It is estimated that the sulfur present in fossil fuels dates back to 600 million tons. The annual production is 63 million tons. The main world producer is the United States (10 million tons) followed by Canada (8.5 million tons) and Russia (6.8 million tons).

Negative effects of sulfur on health

Sulfur can cause stomach problems in the body.

Natural sulfides and sulfur oxides obtained in industrial processes can have harmful effects on human health. To avoid them, safe handling practices must be followed. Can produce:

• Neurological and cardiac damage
• behavior changes
• Altered circulation and breathing
• Affection of the senses: sight and hearing
• Reproductive and immune system involvement and hormone metabolism
• Stomach and gastrointestinal disorders
• Damage to liver and kidney function
• skin irritation on contact
• Irritation of the lungs and mucous membranes by inhalation

Sulfur toxicity

Sulfur is not poisonous in small concentrations, although it is irritating to the mucous membranes and can be metabolized, but in high concentrations, it can cause respiratory arrest.

Sulfur dioxide (SO _{2 ) is an} atmospheric polluting gas, it produces acid rain by transforming into sulfur oxide SO ₃ . Carbon disulfide CS ₂ is highly flammable, its ingestion in small quantities can cause paralysis.

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