Sulfur hexafluoride

Sulfur hexafluoride

Overview
Sulfur hexafluoride is an inorganic
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...

, colorless, odorless, and non-flammable greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

. has an octahedral geometry, consisting of six fluorine
Fluorine
Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...

 atoms attached to a central sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

 atom. It is a hypervalent molecule
Hypervalent molecule
A hypervalent molecule is a molecule that contains one or more main group elements formally bearing more than eight electrons in their valence shells...

. Typical for a nonpolar gas, it is poorly soluble in water but soluble in nonpolar organic solvents. It is generally transported as a liquefied compressed gas
Liquid gas
Due to the age of this content, you may be looking for:*Liquefaction of gases*liquid oxygen*liquid nitrogen*Liquid hydrogen*Liquid helium*paramagnetism *superconducting metals*ferromagnetism *liquified petroleum gas...

. It has a density of 6.12 g/L at sea level conditions, which is considerably higher than the density of air
Density of air
The density of air, ρ , is the mass per unit volume of Earth's atmosphere, and is a useful value in aeronautics and other sciences. Air density decreases with increasing altitude, as does air pressure. It also changes with variances in temperature or humidity...

.

can be prepared from the elements through exposure of
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

 to
Fluorine
Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...

.
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Encyclopedia
Sulfur hexafluoride is an inorganic
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...

, colorless, odorless, and non-flammable greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

. has an octahedral geometry, consisting of six fluorine
Fluorine
Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...

 atoms attached to a central sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

 atom. It is a hypervalent molecule
Hypervalent molecule
A hypervalent molecule is a molecule that contains one or more main group elements formally bearing more than eight electrons in their valence shells...

. Typical for a nonpolar gas, it is poorly soluble in water but soluble in nonpolar organic solvents. It is generally transported as a liquefied compressed gas
Liquid gas
Due to the age of this content, you may be looking for:*Liquefaction of gases*liquid oxygen*liquid nitrogen*Liquid hydrogen*Liquid helium*paramagnetism *superconducting metals*ferromagnetism *liquified petroleum gas...

. It has a density of 6.12 g/L at sea level conditions, which is considerably higher than the density of air
Density of air
The density of air, ρ , is the mass per unit volume of Earth's atmosphere, and is a useful value in aeronautics and other sciences. Air density decreases with increasing altitude, as does air pressure. It also changes with variances in temperature or humidity...

.

Synthesis and reactions


can be prepared from the elements through exposure of
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

 to
Fluorine
Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...

. This was also the method used by the discoverers Henri Moissan
Henri Moissan
Ferdinand Frederick Henri Moissan was a French chemist who won the 1906 Nobel Prize in Chemistry for his work in isolating fluorine from its compounds.-Biography:...

 and Paul Lebeau in 1901. Some other sulfur fluorides are cogenerated, but these are removed by heating the mixture to disproportionate
Disproportionation
Disproportionation, also known as dismutation is used to describe a specific type of redox reaction in which a species is simultaneously reduced and oxidized so as to form two different products....

 any
Disulfur decafluoride
Disulfur decafluoride is a gas discovered in 1934 by Denbigh and Whytlaw-Gray. Each S of the S2F10 molecule is octahedral, and surrounded by 5 fluorines. S2F10 is highly toxic, with toxicity similar to phosgene...

 (which is highly toxic) and then scrubbing the product with NaOH to destroy remaining
Sulfur tetrafluoride
Sulfur tetrafluoride is the chemical compound with the formula SF4. This species exists as a gas at standard conditions. It is a corrosive species that releases dangerous HF upon exposure to water or moisture...

.

There is virtually no reaction chemistry for . It does not react with molten sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...

, but reacts exothermic
Exothermic
In thermodynamics, the term exothermic describes a process or reaction that releases energy from the system, usually in the form of heat, but also in the form of light , electricity , or sound...

ally with lithium
Lithium
Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...

.

Applications


Of the 8,000 tons of produced per year, most (6,000 tons) is used as a gaseous dielectric medium
Dielectric gas
A dielectric gas, or insulating gas, is a dielectric material in gaseous state. Its main purpose is to prevent or rapidly quench electric discharges. Dielectric gases are used as electrical insulators in high voltage applications, e.g...

 in the electrical industry
Electric company
Electric company can mean:*Electrical power industry*Electric Company *The Electric Company *The Electric Company...

, an inert gas
Inert gas
An inert gas is a non-reactive gas used during chemical synthesis, chemical analysis, or preservation of reactive materials. Inert gases are selected for specific settings for which they are functionally inert since the cost of the gas and the cost of purifying the gas are usually a consideration...

 for the casting of magnesium, and as an inert filling for insulated glazing
Insulated glazing
Insulated glazing also known as double glazing are double or triple glass window panes separated by an air or other gas filled space to reduce heat transfer across a part of the building envelope....

 windows.

Dielectric medium


is used in the electrical industry
Electric company
Electric company can mean:*Electrical power industry*Electric Company *The Electric Company *The Electric Company...

 as a gaseous dielectric medium
Dielectric gas
A dielectric gas, or insulating gas, is a dielectric material in gaseous state. Its main purpose is to prevent or rapidly quench electric discharges. Dielectric gases are used as electrical insulators in high voltage applications, e.g...

 for high-voltage circuit breaker
Sulfur hexafluoride circuit breaker
High-voltage circuit-breakers have greatly changed since they were first introduced in the mid-1950s, and several interrupting principles have been developed that have contributed successively to a large reduction of the operating energy...

s, switchgear
Switchgear
The term switchgear, used in association with the electric power system, or grid, refers to the combination of electrical disconnects, fuses and/or circuit breakers used to isolate electrical equipment. Switchgear is used both to de-energize equipment to allow work to be done and to clear faults...

, and other electrical
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

 equipment, often replacing oil filled circuit breakers (OCBs) that can contain harmful PCBs. gas under pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

 is used as an insulator in gas insulated switchgear
Switchgear
The term switchgear, used in association with the electric power system, or grid, refers to the combination of electrical disconnects, fuses and/or circuit breakers used to isolate electrical equipment. Switchgear is used both to de-energize equipment to allow work to be done and to clear faults...

 (GIS) because it has a much higher dielectric strength
Dielectric strength
In physics, the term dielectric strength has the following meanings:*Of an insulating material, the maximum electric field strength that it can withstand intrinsically without breaking down, i.e., without experiencing failure of its insulating properties....

 than air or dry nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

. This property makes it possible to significantly reduce the size of electrical gear. This makes GIS more suitable for certain purposes such as indoor placement, as opposed to air-insulated electrical gear, which takes up considerably more room. Gas-insulated electrical gear is also more resistant to the effects of pollution and climate, as well as being more reliable in long-term operation because of its controlled operating environment. Although most of the decomposition products tend to quickly re-form , arcing or corona
Corona discharge
In electricity, a corona discharge is an electrical discharge brought on by the ionization of a fluid surrounding a conductor that is electrically energized...

 can produce disulfur decafluoride
Disulfur decafluoride
Disulfur decafluoride is a gas discovered in 1934 by Denbigh and Whytlaw-Gray. Each S of the S2F10 molecule is octahedral, and surrounded by 5 fluorines. S2F10 is highly toxic, with toxicity similar to phosgene...

 (
Disulfur decafluoride
Disulfur decafluoride is a gas discovered in 1934 by Denbigh and Whytlaw-Gray. Each S of the S2F10 molecule is octahedral, and surrounded by 5 fluorines. S2F10 is highly toxic, with toxicity similar to phosgene...

), a highly toxic gas, with toxicity similar to phosgene
Phosgene
Phosgene is the chemical compound with the formula COCl2. This colorless gas gained infamy as a chemical weapon during World War I. It is also a valued industrial reagent and building block in synthesis of pharmaceuticals and other organic compounds. In low concentrations, its odor resembles...

. was considered a potential chemical warfare
Chemical warfare
Chemical warfare involves using the toxic properties of chemical substances as weapons. This type of warfare is distinct from Nuclear warfare and Biological warfare, which together make up NBC, the military acronym for Nuclear, Biological, and Chemical...

 agent in World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 because it does not produce lacrimation or skin irritation, thus providing little warning of exposure.

is also commonly encountered as a high voltage dielectric in the high voltage supplies of particle accelerator
Particle accelerator
A particle accelerator is a device that uses electromagnetic fields to propel charged particles to high speeds and to contain them in well-defined beams. An ordinary CRT television set is a simple form of accelerator. There are two basic types: electrostatic and oscillating field accelerators.In...

s, such as Van de Graaff generator
Van de Graaff generator
A Van de Graaff generator is an electrostatic generator which uses a moving belt to accumulate very high voltages on a hollow metal globe on the top of the stand. It was invented in 1929 by American physicist Robert J. Van de Graaff. The potential differences achieved in modern Van de Graaff...

s and Pelletron
Pelletron
A pelletron is a type of electrostatic particle accelerator similar to a Van de Graaff generator. Pelletrons have been built in many sizes, from small units producing voltages up to 500 kilovolts and beam energies up to 1 megaelectronvolt of kinetic energy, to the largest system, which has...

s and high voltage transmission electron microscope
Electron microscope
An electron microscope is a type of microscope that uses a beam of electrons to illuminate the specimen and produce a magnified image. Electron microscopes have a greater resolving power than a light-powered optical microscope, because electrons have wavelengths about 100,000 times shorter than...

s.

Medical use


is used to provide a tamponade
Tamponade
Tamponade is the closure or blockage as if by a tampon especially to stop bleeding.Tamponade is a useful method of stopping a hemorrhage...

 or plug of a retinal hole in retinal detachment
Retinal detachment
Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blindness. It is a medical emergency.The retina is a...

 repair operations. It is inert in the vitreous chamber
Vitreous chamber
The vitreous chamber or postremal chamber occupies posterior 4/5ths of the eyeball. This chamber of consists of the space between the lens and the retina, and is filled with a transparent gel called the vitreous humor....


and initially doubles its volume in 36 hours before being absorbed in the blood in 10–14 days.

is used as a contrast agent for ultrasound
Medical ultrasonography
Diagnostic sonography is an ultrasound-based diagnostic imaging technique used for visualizing subcutaneous body structures including tendons, muscles, joints, vessels and internal organs for possible pathology or lesions...

 imaging. Sulfur hexafluoride microbubbles are administered in solution through injection into a peripheral vein. These microbubbles enhance the visibility of blood vessels to ultrasound. This application has been utilized to examine the vascularity of tumours.

Tracer compound


Sulfur hexafluoride was the tracer gas used in the first roadway air dispersion model calibration; this research program was sponsored by the U.S. Environmental Protection Agency and conducted in Sunnyvale, California
Sunnyvale, California
Sunnyvale is a city in Santa Clara County, California, United States. It is one of the major cities that make up the Silicon Valley located in the San Francisco Bay Area...

 on U.S. Highway 101. Gaseous is used as a tracer gas in short-term experiments of ventilation
Ventilation (architecture)
Ventilating is the process of "changing" or replacing air in any space to provide high indoor air quality...

 efficiency in buildings and indoor enclosures, and for determining infiltration
Infiltration (HVAC)
Infiltration is the unintentional or accidental introduction of outside air into a building, typically through cracks in the building envelope and through use of doors for passage. Infiltration is sometimes called air leakage. The leakage of room air out of a building, intentionally or not, is...

 rates. Two major factors recommend its use: its concentration can be measured with satisfactory accuracy at very low concentrations, and the Earth's atmosphere
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...

 has a negligible concentration of .

Sulfur hexafluoride was used as a non-toxic test gas in an experiment at St John's Wood tube station
St John's Wood tube station
St John's Wood tube station is a London Underground station at St John's Wood. It is on the Jubilee Line, between Swiss Cottage and Baker Street. It is in Travelcard Zone 2...

 in London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

, United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 on 25 March 2007. The gas was released throughout the station, and monitored as it drifted around. The purpose of the experiment, which had been announced earlier in March by the Secretary of State for Transport
Secretary of State for Transport
The Secretary of State for Transport is the member of the cabinet responsible for the British Department for Transport. The role has had a high turnover as new appointments are blamed for the failures of decades of their predecessors...

 Douglas Alexander
Douglas Alexander
Douglas Garven Alexander is a British Labour Party politician, who is currently the Shadow Secretary of State for Foreign and Commonwealth Affairs in the shadow cabinet of Ed Miliband. He has held cabinet posts under Tony Blair and Gordon Brown, including Secretary of State for Scotland and...

, was to investigate how toxic gas might spread throughout London Underground
London Underground
The London Underground is a rapid transit system serving a large part of Greater London and some parts of Buckinghamshire, Hertfordshire and Essex in England...

 stations and buildings during a terrorist attack.

It has been used successfully as a tracer in oceanography
Oceanography
Oceanography , also called oceanology or marine science, is the branch of Earth science that studies the ocean...

 to study diapycnal mixing and air-sea gas exchange.

Other uses


Sulfur hexafluoride is also used as a reagent
Reagent
A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...

 for creating thrust in a closed Rankine-cycle
Rankine cycle
The Rankine cycle is a cycle that converts heat into work. The heat is supplied externally to a closed loop, which usually uses water. This cycle generates about 90% of all electric power used throughout the world, including virtually all solar thermal, biomass, coal and nuclear power plants. It is...

 propulsion system, reacting with solid
Solid
Solid is one of the three classical states of matter . It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a...

 lithium
Lithium
Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...

 as used in the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

's Mark 50 torpedo
Mark 50 torpedo
The Mark 50 torpedo is a U.S. Navy advanced lightweight torpedo for use against fast, deep-diving submarines. The Mk-50 can be launched from all anti-submarine aircraft and from torpedo tubes aboard surface combatant ships. The Mk-50 was intended to replace the Mk-46 as the fleet's lightweight...

.

plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...

 is also used in the semiconductor
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...

 industry as an etchant
Etching (microfabrication)
Etching is used in microfabrication to chemically remove layers from the surface of a wafer during manufacturing. Etching is a critically important process module, and every wafer undergoes many etching steps before it is complete....

. breaks down in the plasma into sulfur and fluorine, the fluorine plasma performing the etching.

The magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

 industry uses large amounts of as inert gas to fill casting forms.

Sulfur hexafluoride is also used to pressurize waveguide
Waveguide
A waveguide is a structure which guides waves, such as electromagnetic waves or sound waves. There are different types of waveguides for each type of wave...

s in radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 systems. The gas insulates the waveguide preventing internal arcing. The same use of sulfur hexafluoride is applied in transmission waveguides of medical linear accelerators, which are used for delivery of external beam radiotherapy.

Sulfur hexafluoride has been used in electrostatic loudspeakers because of its high dielectric strength and high molecular weight.

Greenhouse gas



According to the Intergovernmental Panel on Climate Change
Intergovernmental Panel on Climate Change
The Intergovernmental Panel on Climate Change is a scientific intergovernmental body which provides comprehensive assessments of current scientific, technical and socio-economic information worldwide about the risk of climate change caused by human activity, its potential environmental and...

, is the most potent greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...

 that it has evaluated, with a global warming potential
Global warming potential
Global-warming potential is a relative measure of how much heat a greenhouse gas traps in the atmosphere. It compares the amount of heat trapped by a certain mass of the gas in question to the amount of heat trapped by a similar mass of carbon dioxide. A GWP is calculated over a specific time...

 of 22,800 times that of
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 when compared over a 100-year period. Measurements of SF6 show that its global average mixing ratio has increased by about 0.2 ppt per year to over 7 ppt. Sulfur hexafluoride is also extremely long-lived, is inert in the troposphere and stratosphere and has an estimated atmospheric lifetime of 800–3200 years. is very stable (for countries reporting their emissions to the UNFCCC, a GWP of 23,900 for was suggested at the third Conference of the Parties: GWP used in Kyoto protocol). Average global SF6 concentrations increased by about seven percent per year during the 1980s and 1990s, mostly as the result of its use in the magnesium production industry, and by electrical utilities and electronics manufacturers. Given the low amounts of SF6 released compared to carbon dioxide, its overall contribution to global warming is estimated to be less than 0.2 percent.

In Europe, falls under the F-Gas directive which ban or control its usage for several applications. Since 1 January 2006, is banned as a tracer gas and in all applications except high-voltage switchgear.

Physiological effects and precautions


Another effect is the gas's ability to alter vocal sound waves. This is due to the gas's large molar mass
Molar mass
Molar mass, symbol M, is a physical property of a given substance , namely its mass per amount of substance. The base SI unit for mass is the kilogram and that for amount of substance is the mole. Thus, the derived unit for molar mass is kg/mol...

. Unlike helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...

, which has a molar mass of about 4 grams/mol, has a molar mass of about 146 g/mol, and the velocity of sound through the gas is 0.44 times the speed of sound in air due to the large inertia
Inertia
Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...

 of a molecule. For comparison, the molar mass of air, which is about 80% nitrogen and 20% oxygen, is approximately 30 g/mol. Inhalation of causes a lowering of the timbre
Timbre
In music, timbre is the quality of a musical note or sound or tone that distinguishes different types of sound production, such as voices and musical instruments, such as string instruments, wind instruments, and percussion instruments. The physical characteristics of sound that determine the...

, or frequency of the formants, of the vocal tract, by contrast with inhalation of helium, which raises it.

Other properties


Thermal conductivity at STP (101.3 kPa and 0 °C) = 12.058 mW/(m.K)

Heat capacity at constant pressure (Cp) (101.3 kPa and 21 °C) = 0.097 kJ/(mol.K)

See also

  • Selenium hexafluoride
    Selenium hexafluoride
    Selenium hexafluoride is the inorganic compound with the formula SeF6. It is a colourless gas described as having a "repulsive" odor. It is not widely encountered and has no commercial applications.-Structure, preparation, and reactions:...

  • Tellurium hexafluoride
    Tellurium hexafluoride
    Tellurium hexafluoride is the oldest known fluoride of tellurium. It is a colorless, highly toxic gas with an extremely unpleasant smell.-Preparation:...

  • Hypervalent molecule
    Hypervalent molecule
    A hypervalent molecule is a molecule that contains one or more main group elements formally bearing more than eight electrons in their valence shells...

  • Process for Measuring the Degradation of Sulfur Hexafluoride in High-voltage Systems
    Isidor Sauers
    Isidor Sauers is an Austrian-born American who is a physicist at the Oak Ridge National Laboratory in Tennessee. He is a specialist on the properties of Sulfur hexafluoride , with an important patent and over 60 peer-reviewed academic papers....

     
  • Halocarbon
    Halocarbon
    Halocarbon compounds are chemicals in which one or more carbon atoms are linked by covalent bonds with one or more halogen atoms resulting in the formation of organofluorine compounds, organochlorine compounds, organobromine compounds, and organoiodine compounds...

    —another group of major greenhouse gases

Further reading


External links