Sulfur

Figure 1. Sulfur, atomic number of 16 and atomic weight of 32.065.

Sulfur (S) is the 16^th element on the periodic table. Sulfur is the tenth most abundant element in the universe, and it is fairly common on Earth as well. It is a pale yellow, odourless, and brittle material that has been known since ancient times. 25% of today's produced sulfur is recovered from the petroleum refining process or the process of extracting materials from ores containing sulfur. Most sulfur is produced from underground deposits.

Sulfur is used in a variety of ways in both gaseous and solid compounds, however sulfur is also a major component of the group of pollutants known collectively as sulfur oxides or SO_x.

Some properties of sulfur include:

Atomic weight	32.065
Density (at 0oC)	2.067 g/cm3
Boiling point	717.75 K
Melting point	388.36 K

Uses

Sulfur is commonly used to create sulfuric acid, which is used in a number of different industries. Specifically, sulfuric acid is used to make fertilizers and lead-acid batteries. As well, sulfur is used in the production or inorganic chemicals, matches, explosives, cement, and glass.

Along with sulfuric acid, sulfur forms compounds such as hydrogen sulfide and sulfur dioxide. Sulfur dioxide is used as a bleaching agent, solvent, disinfectant, and refrigerant. However, when combined with water it forms sulfurous acid, which is a major component of acid rain.

Sulfur Oxides

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Sulfur dioxide, SO₂ is the most common sulfur oxide in the lower atmosphere. It is colourless, but has a distinct smell and taste that can be detected if the gas has a high enough concentration. Sulfur oxides dissolve readily in water, and result in the atmospheric formation of sulfurous acid or sulfuric acid - a component of acid rain.

Most sulfur oxides are produced when fuels that contain sulfur undergo combustion. Coal burning power plants that burn high-sulfur coal are some of the main sources of SO_x. Vehicles can also be a source of sulfur oxides. Exposure to these oxides can be harmful to human health since they are irritants. Side effects of exposure include reduced lung function, increased incidence of respiratory diseases, irritation of the eyes, nose, and throat, and even death.

Hydrogen Sulfide

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Sulfur is also important as it is a component of hydrogen sulfide, or H₂S. Hydrogen sulfide is a dangerous, colourless gas that occurs naturally in many petroleum products but can make up significant amounts of natural gas. This hydrogen sulfide content is one of the main safety concerns associated with the use of natural gas. The health effects of inhalation depend on how much hydrogen sulfide a person is exposed to. Hydrogen sulfide is dangerous even at relatively small concentrations. At certain concentrations, exposure to hydrogen sulfide can result in unconsciousness in 1-2 breaths or even near instant death. Health effects of exposure include headaches, memory loss, and problems with the cardiovascular system. Additionally, hydrogen sulfide is dangerous as it is highly flammable and explosive.

Natural gas with especially high levels of hydrogen sulfide is referred to as sour gas. Some of this sulfur can be removed through a "sweetening" process, which is done mainly using amine solutions that remove this hydrogen sulfide. The process used is known as the "amine process" or more commonly the "Girdler process", and it is used in most gas sweetening operations.

Video

The video below is from the University of Nottingham's periodic videos project. They have created a complete suite of short videos on every element on the periodic table of elements.