Hydrogen selenide
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| Names | |||
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IUPAC name
Hydrogen selenide
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| Other names
Hydroselenic acid
selane selenium hydride |
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| Identifiers | |||
7783-07-5 
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| 3D model (Jmol) | Interactive image | ||
| ChEBI |
CHEBI:16503
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| ChemSpider |
518
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| ECHA InfoCard | 100.029.071 | ||
| KEGG |
C01528
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| PubChem | 533 | ||
| RTECS number | X1050000 | ||
| UNII |
V91P54KPAM 
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| UN number | 2202 | ||
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| Properties | |||
| H2Se | |||
| Molar mass | 80.98 g/mol | ||
| Appearance | Colorless gas | ||
| Odor | decayed horseradish | ||
| Density | 3.553 g/cm3 | ||
| Melting point | −65.73 °C (−86.31 °F; 207.42 K) | ||
| Boiling point | −41.25 °C (−42.25 °F; 231.90 K) | ||
| 0.70 g/100 mL | |||
| Solubility | soluble in CS2, phosgene | ||
| Vapor pressure | 9.5 atm (21°C) | ||
| Acidity (pKa) | 3.89 | ||
| Structure | |||
| Bent | |||
| Hazards | |||
| Safety data sheet | ICSC 0284 | ||
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EU classification (DSD)
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 F+  T  N
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| R-phrases | R23/25, R33, R50/53 | ||
| S-phrases | (S1/2), S20/21, S28, S45, S60, S61 | ||
| NFPA 704 | |||
| Flash point | flammable gas | ||
| Lethal dose or concentration (LD, LC): | |||
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LCLo (lowest published)
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0.3 ppm (guinea pig, 8 hr) 5.9 ppm (rat, 1 hr) |
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| US health exposure limits (NIOSH): | |||
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PEL (Permissible)
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TWA 0.05 ppm (0.2 mg/m3) | ||
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REL (Recommended)
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TWA 0.05 ppm (0.2 mg/m3) | ||
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IDLH (Immediate danger)
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1 ppm | ||
| Related compounds | |||
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Other anions
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H2O H2S H2Te H2Po |
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Other cations
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Na2Se Ag2Se |
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Related compounds
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Arsine | ||
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is ?) |
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| Infobox references | |||
Hydrogen selenide is an inorganic compound with the formula H2Se. This hydrogen chalcogenide is the simplest and most commonly encountered hydride of selenium. H2Se is a colorless, flammable gas under standard conditions. It is the most toxic selenium compound with an exposure limit of 0.05 ppm over an 8-hour period. Even at extremely low concentrations, this compound has a very irritating smell resembling that of decayed horseradish or 'leaking gas', but smells of rotten eggs at higher concentrations.
H2Se adopts a "bent" structure with a H-Se-H bond angle of 91°. Consistent with this structure, three IR-active vibrational bands are observed: 2358, 2345, and 1034 cm−1.
The properties of H2S and H2Se are similar, although the selenide is more acidic with pKa = 3.89, and the second pKa = 11.0 at 25 °C. Reflecting its acidity, H2Se is soluble in water.
Industrially, it is produced by treating elemental selenium at T > 300 °C with hydrogen gas. A number of routes to H2Se have been reported, which are suitable for both large and small scale preparations. In the laboratory, H2Se is usually prepared by the action of water on Al2Se3, concomitant with formation of hydrated alumina. A related reaction involves the acid hydrolysis of FeSe.
H2Se can also be prepared by means of different methods based on the in situ generation in aqueous solution using boron hydride, Marsh test and Devarda's alloy. According to the Sonoda method, H2Se is generated from the reaction of H2O and CO on Se in the presence of Et3N. H2Se can be purchased in cylinders.
Elemental selenium can be recovered from H2Se through a reaction with aqueous sulfur dioxide (SO2).
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