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Sodium hydrosulfide
IUPAC name	Sodium hydrosulfide
Other names	Sodium bisulfide; Sodium sulfhydrate; Sodium hydrogen sulfide
Identifiers
CAS number	16721-80-5 ,; 207683-19-0 (hydrate)
PubChem	28015
EC number	240-778-0
RTECS number	WE1900000
InChI	1/Na.H2S/h;1H2/q+1;/p-1
InChI key	HYHCSLBZRBJJCH-REWHXWOFAV
ChemSpider ID	26058
Properties
Molecular formula	NaHS
Molar mass	56.063 g/mol
Appearance	off-white solid, deliquescent
Density	1.79 g/cm3
Melting point	52–54 ºC (hydrate); 350 ºC (anhydrous)
Hazards
MSDS	TDC MSDS
EU Index	Not listed
Main hazards	Flammable solid, stench, releases hydrogen sulfide
NFPA 704	2 3 0
Flash point	90 ºC
Related compounds
Other anions	Sodium hydroxide; Sodium amide
Other cations	Ammonium hydrosulfide
Related compounds	Sodium sulfide
	(what is this?) (verify); Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 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 a sodium-derived base. NaHS is a useful reagent for the synthesis of organic and inorganic sulfur compounds. It is a colorless solid that typically smells like H₂S due to hydrolysis by atmospheric moisture. In contrast with 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 SH^- are sensitive to oxygen, converting mainly to polysulfides, indicated by the appearance of yellow.

[edit] Structure and properties

Crystalline NaHS undergoes two phase transitions. At temperatures above 360K, 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 360K, a rhombohedral structure forms, and the HS^- sweeps out a discoidal shape. Below 114K, 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.

[edit] Preparation

The usual laboratory synthesis entails treatment of 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.

[edit] Applications

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.

[edit] References

^ 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: 1269–1276. doi:10.1063/1.1483860.
^ Eibeck, R. I. (1963), "Sodium Hydrogen Sulfide", Inorg. Synth. 7: 128–31, doi:10.1002/9780470132388.ch35

[0] 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: 1269–1276. doi:10.1063/1.1483860.

[1] Eibeck, R. I. (1963), "Sodium Hydrogen Sulfide", Inorg. Synth. 7: 128–31, doi:10.1002/9780470132388.ch35

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Contents

[edit] Structure and properties

[edit] Preparation

[edit] Applications

[edit] References