Sodium hydrosulfide Names IUPAC name Other names Identifiers ChEMBL ChemSpider ECHA InfoCard 100.037.056 EC Number RTECS number UNII UN number 2922 2318 Properties NaSH Molar mass 56.063 g/mol Appearance off-white solid, deliquescent Density 1.79 g/cm3 Melting point 350.1 °C (662.2 °F; 623.2 K) (anhydrous) 55 °C (dihydrate) 22 °C (trihydrate) 50 g/100 mL (22 °C) Solubility Soluble in alcohol, ether Structure rhombohedral Hazards Occupational safety and health (OHS/OSH): Flammable solid, stench, reacts with acids to release hydrogen sulfide GHS labelling: Danger H226, H251, H290, H301, H314, H400 P210, P233, P234, P235+P410, P240, P241, P242, P243, P260, P264, P270, P273, P280, P301+P310, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P330, P363, P370+P378, P390, P391, P403+P235, P404, P405, P407, P413, P420, P501 NFPA 704 (fire diamond) Flash point 90 °C (194 °F; 363 K) Safety data sheet (SDS) TDC MSDS Related compounds Sodium hydroxideSodium amide Ammonium hydrosulfide Sodium sulfide
Sodium hydrosulfide is the chemical compound with the formula NaSH. This compound is the product of the half-neutralization of hydrogen sulfide (H2S) with sodium hydroxide (NaOH). NaSH and sodium sulfide are used industrially, often for similar purposes. Solid NaSH is colorless. The solid has an odor of H2S owing to hydrolysis by atmospheric moisture. In contrast with sodium sulfide (Na2S), which is insoluble in organic solvents, NaSH, being a 1:1 electrolyte, is more soluble.
Crystalline NaSH undergoes two phase transitions. At temperatures above 360 K, NaSH adopts the NaCl structure, which implies that the HS− behaves as a spherical anion owing 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]
NaSH has a relatively low melting point of 350 °C. In addition to the aforementioned anhydrous forms, it can be obtained as two hydrates, NaSH·2H2O and NaSH·3H2O.[2] These three species are all colorless and behave similarly but not identically.
A laboratory synthesis entails treatment of sodium ethoxide (NaOEt) with hydrogen sulfide:[2]
NaOCH2CH3 + H2S → NaSH + CH3CH2OH
An alternative method involves reaction of sodium with hydrogen sulfide.[3]
Thousands of tons of NaSH are produced annually. Its main uses are in cloth and 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.[4]
