User:Milton Beychok/Sandbox: Difference between revisions

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<u>'''Hydrogen Sulfide'''</u>
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'''Hydrogen sulfide''' ([[British English]]: ''hydrogen sulphide'') is a [[chemical compound]] with the [[chemical formula|formula]] [[Hydrogen|H]]<sub>2</sub>[[Sulfur|S]]. It is a colorless, highly toxic,  flammable [[gas]] with a characteristic foul odor.
It often results from the [[bacterial]] breakdown of [[organic matter]] in the absence of [[oxygen]], such as in [[swamp]]s and sewers ([[anaerobic digestion]]). It also occurs in [[volcano|volcanic]] gases, [[natural gas]], [[petroleum crude oil]] and some well waters.
==Chemical properties==
==Chemical properties==


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| '''Liquid [[Density (chemistry)|density]]''' || 914.9 kg/m<sup>3</sup> at -60.35 °C and 1 atm
| '''Liquid [[Density (chemistry)|density]]''' || 914.9 kg/m<sup>3</sup> at -60.35 °C and 1 atm
|- align=left
| '''Liquid [[Viscosity]]'''||0.076 centipoise at 25 °C
|- align=left
|- align=left
| '''Gas [[Density (chemistry)|density]]'''||1.93 kg/m<sup>3</sup> at -60.35 °C and 1 atm,<br/>1.411kg/m<sup>3</sup> at 20°C and 1 atm  
| '''Gas [[Density (chemistry)|density]]'''||1.93 kg/m<sup>3</sup> at -60.35 °C and 1 atm,<br/>1.411kg/m<sup>3</sup> at 20°C and 1 atm  
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| ''' Gas [[specific heat ratio]], c<sub>p</sub>/c<sub>v</sub>''' || 1.32 at 25 °C and 1 atm
| ''' Gas [[specific heat ratio]], c<sub>p</sub>/c<sub>v</sub>''' || 1.32 at 25 °C and 1 atm
|- align=left
|- align=left
| '''[[Viscosity]]'''||
| '''Gas [[Viscosity]]'''||126.02 micropoise at 25 °C
|- align="left"
|- align="left"
| '''[[Refractive index]]'''||
| '''[[Refractive index]]'''||
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Hydrogen sulfide reacts with alcohols to form [[thiol]]s.
Hydrogen sulfide reacts with alcohols to form [[thiol]]s.
==Toxicity==
Hydrogen sulfide is considered a broad-spectrum poison, meaning that it can poison several different systems in the body, although the [[nervous system]] is most affected.
* 0.00047 [[parts-per notation|ppm]] is the recognition threshold, the concentration at which 50% of humans can detect the characteristic foul odor of hydrogen sulfide.<ref>[http://www.extension.iastate.edu/Publications/PM1963A.pdf Odor perception and physiological  response]</ref>
* At 100–150 ppm the [[olfactory nerve]] is paralyzed after a few inhalations, and the sense of smell disappears, often together with awareness of danger.<ref>USEPA; Health and Environmental Effects Profile for Hydrogen Sulfide p.118-8 (1980) ECAO-CIN-026A  ???</ref><ref>Zenz, C., O.B. Dickerson, E.P. Horvath. ''Occupational Medicine.'' 3rd ed. St. Louis, MO., 1994, p.886 /publisher.ISBN???</ref>
* 320–530 ppm leads to [[pulmonary edema]] with the possibility of death.
* 530–1000 ppm causes strong stimulation of the [[central nervous system]] and rapid breathing, leading to loss of breathing.
* 800 ppm is the lethal concentration for 50% of humans for 5 minutes exposure ([[LC50]]).
* Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.
==Occurrence==
Small amounts of hydrogen sulfide occur in [[crude petroleum]], but [[natural gas]] can contain up to XX %. [[Volcano]]es and some [[hot spring]]s emit some H<sub>2</sub>S, where it probably arises via the [[hydrolysis]] of sulfide minerals
About 10%  (???) of total global emissions of H<sub>2</sub>S is due to human activity. By far the largest industrial route to H<sub>2</sub>S occurs in [[oil refinery|petroleum refineries]]: The [[hydrodesulfurization]] process liberates sulfur from [[petroleum]] by the action of hydrogen. The resulting H<sub>2</sub>S is converted to elemental sulfur by partial combustion via the [[Claus process]], which is a major source of elemental sulfur.
==References==
{{reflist}}

Revision as of 02:13, 2 March 2011

Chemical properties

Properties
Property Value
Common name hydrogen sulfide
Other names hydrogen sulphide, dihydrogen sulfide, sulfur hydride, hydrosulfuric acid, sewer gas
IUPAC name hydrogen sulfide
CAS number 7783-06-04
Molecular formula H2S
Molecular mass 34.082 g/mol
Melting point -85.47 °C
Normal boiling point -60.35 °C and 1 atm
Critical point 100.38 °C at 88.46 atm
Heat of fusion 69.74 kJ/kg at -85.47 °C and 1 atm
Heat of vaporization 517.87 kJ/kg at -60.35 °C and 1 atm
413.15 kJ/kg at 25 °C and 1 atm
Liquid density 914.9 kg/m3 at -60.35 °C and 1 atm
Liquid Viscosity 0.076 centipoise at 25 °C
Gas density 1.93 kg/m3 at -60.35 °C and 1 atm,
1.411kg/m3 at 20°C and 1 atm
Gas specific heat, cp 1.005 kJ/(kg·K) at 25 °C and 1 atm
Gas specific heat, cv 0.761 kJ/(kg·K) at 25 °C and 1 atm
Gas specific heat ratio, cp/cv 1.32 at 25 °C and 1 atm
Gas Viscosity 126.02 micropoise at 25 °C
Refractive index

Hydrogen sulfide is a highly toxic and flammable gas (Flammability range: 4.3 % - 46 % volume % in air). Being heavier than air, it tends to accumulate at the bottom of poorly ventilated spaces. Although very pungent at first, it quickly deadens the sense of smell, so potential victims may be unaware of its presence until it is too late. For safe handling procedures, a hydrogen sulfide material safety data sheet (MSDS) should be consulted.[1]

Hydrogen sulfide and oxygen burn with a blue flame to form sulfur dioxide (SO2) and [|water]]. In general, hydrogen sulfide acts as a reducing agent.

At high temperature and in the presence of catalysts, sulfur dioxide can be made to react with hydrogen sulfide to form elemental sulfur and water. This is exploited in the Claus process, the main way to convert hydrogen sulfide into elemental sulfur.

Hydrogen sulfide is slightly soluble in water and acts as a weak acid, giving the hydrosulfide ion HS− (pKa=6.9 in 0.01-0.1 mol/litre solutions at 18°C) and the sulfide ion S2− (pKa=11.96).

Hydrogen sulfide reacts with metal ions to form metal sulfides, which may be considered the salts of hydrogen sulfide. Some ores are sulfides. Metal sulfides often have a dark color.

If gaseous hydrogen sulfide is put into contact with concentrated nitric acid, it explodes.

Hydrogen sulfide reacts with alcohols to form thiols.

  1. ↑ Hydrogen Sulfide Material Safety Data Sheet (MSDS) Iowa State University, Department of Chemistry
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