Sodium hydrosulfide

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Sodium hydrosulfide
Identifiers
CAS number16721-80-5 YesY
207683-19-0 (hydrate)
PubChem28015
ChemSpider26058 YesY
UNIIFWU2KQ177W YesY
EC number240-778-0
ChEMBLCHEMBL1644699 N
RTECS numberWE1900000
Jmol-3D imagesImage 1
Properties
Molecular formulaNaHS
Molar mass56.063 g/mol
Appearanceoff-white solid, deliquescent
Density1.79 g/cm3
Melting point350 ºC (anhydrous)
55 °C (dihydrate)
22 °C (trihydrate)
Solubility in water50 g/100 mL (22 °C)
Solubilitysoluble in alcohol, ether
Structure
Crystal structurerhombohedral
Hazards
MSDSTDC MSDS
EU IndexToxic
R-phrasesR17 R23 R24 R25
Main hazardsFlammable solid, stench, releases hydrogen sulfide
NFPA 704
NFPA 704.svg
2
3
0
Flash point90 °C; 194 °F; 363 K
Related compounds
Other anionsSodium hydroxide
Sodium amide
Other cationsAmmonium hydrosulfide
Related compoundsSodium sulfide
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references
 
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Sodium hydrosulfide
Identifiers
CAS number16721-80-5 YesY
207683-19-0 (hydrate)
PubChem28015
ChemSpider26058 YesY
UNIIFWU2KQ177W YesY
EC number240-778-0
ChEMBLCHEMBL1644699 N
RTECS numberWE1900000
Jmol-3D imagesImage 1
Properties
Molecular formulaNaHS
Molar mass56.063 g/mol
Appearanceoff-white solid, deliquescent
Density1.79 g/cm3
Melting point350 ºC (anhydrous)
55 °C (dihydrate)
22 °C (trihydrate)
Solubility in water50 g/100 mL (22 °C)
Solubilitysoluble in alcohol, ether
Structure
Crystal structurerhombohedral
Hazards
MSDSTDC MSDS
EU IndexToxic
R-phrasesR17 R23 R24 R25
Main hazardsFlammable solid, stench, releases hydrogen sulfide
NFPA 704
NFPA 704.svg
2
3
0
Flash point90 °C; 194 °F; 363 K
Related compounds
Other anionsSodium hydroxide
Sodium amide
Other cationsAmmonium hydrosulfide
Related compoundsSodium sulfide
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Sodium hydrosulfide is the chemical compound with the formula NaHS. This compound is the product of the half neutralization of hydrogen sulfide with sodium hydroxide. NaHS is a useful reagent for the synthesis of organic and inorganic sulfur compounds, sometimes as a solid reagent, and more often as an aqueous solution. Solid NaHS is colorless and typically smells like H2S due to hydrolysis by atmospheric moisture. In contrast with sodium sulfide, Na2S, which is insoluble in organic solvents, NaHS, being a 1:1 electrolyte, is more soluble. Alternatively, in place of NaHS, H2S can be treated with an organic amine to generate an ammonium salt. Solutions of HS are sensitive to oxygen, converting mainly to polysulfides, indicated by the appearance of yellow.

Structure and properties[edit]

Crystalline NaHS undergoes two phase transitions. At temperatures above 360 K, NaHS adopts the NaCl structure, which implies that the HS behaves as a spherical anion due to its rapid rotation leading to equal occupancy of eight equivalent positions. Below 360 K, a rhombohedral structure forms, and the HS sweeps out a discoidal shape. Below 114 K, the structure becomes monoclinic. The analogous rubidium and potassium compounds behave similarly.[1]

NaHS has a relatively low melting point of 350 °C. In addition to the aforementioned anhydrous forms, it can be obtained as two different hydrates, NaHS·2H2O and NaHS·3H2O. These three species are all colorless and behave similarly, but not identically.

Preparation[edit]

The usual laboratory synthesis entails treatment of sodium methoxide, NaOMe, with hydrogen sulfide:[2]

NaOMe + H2S → NaHS + MeOH

Industrially, NaOH is employed as the base. The quality of the NaHS can be assayed by iodometric titration, exploiting the ability of HS to reduce I2.

Applications[edit]

Thousands of tons of NaHS are produced annually. Its main uses are in paper manufacture as a makeup chemical for sulfur used in the Kraft process, as a flotation agent in copper mining where it is used to activate oxide mineral species, and in the leather industry for the removal of hair from hides.

References[edit]

  1. ^ Haarmann, F.; Jacobs, H.; Roessler, E.; Senker, J. (2002). "Dynamics of anions and cations in hydrogensulfides of alkali metals (NaHS, KHS, RbHS): A proton nuclear magnetic resonance study". J. Chem. Phys. 117 (3): 1269–1276. doi:10.1063/1.1483860. 
  2. ^ Eibeck, R. I.; Zingaro, Ralph A.; McGlothlin, Raymond E. (1963). "Sodium Hydrogen Sulfide". Inorg. Synth. Inorganic Syntheses 7: 128–31. doi:10.1002/9780470132388.ch35. ISBN 978-0-470-13238-8