Hydrogen Sulfide

34.08

33.988

3535004

231-977-3

TSCA listed

colorless gas; flammable

2830909000

1

H2S is soluble in carbon disulfide, methanol, acetone and alkanolamines. A solution of hydrogen sulfide in water is initially clear but over time turns cloudy. This is due to the slow reaction of hydrogen sulfide with the oxygen dissolved in water, yielding elemental sulfur, which precipitates out.

0.5

Hydrogen sulfide appears as a colorless gas having a strong odor of rotten eggs. Boiling point -60.2°C. Shipped as a liquid confined under its own vapor pressure. Density (liquid) 8.3 lb / gal. Contact with the unconfined liquid can cause frostbite by evaporative cooling. Gas is very toxic by inhalation. Fatigues the sense of smell which cannot be counted on to warn of the continued presence of the gas. Prolonged exposure of closed containers to heat may result in their violent rupturing and rocketing. Rate of onset: Immediate & Delayed Persistence: Minutes to hours Odor threshold: 0.1 ppm Source/use/other hazard: Disinfectant lubricant/oils; interm for HC manufacture; deadens sense of smell.

dgas 1.19 (air = 1.00)

−85 °C(lit.)

−60 °C(lit.)

-17℃

1g dissolves in H2O: 187mL (10°C), 242mL (20°C), 314 (30°C) [MER06]

2-8°C

252 psi ( 21 °C)

1.19 (15 °C, vs air)

Toxicity of hydrogen sulfide is most likely related to inhibition of metal-containing enzymes such as cytochrome oxidase, the final enzyme of the mitochondrial respiratory chain, and carbonic anhydrase. Therefore, hydrogen sulfide affects cellular energy production and respiration. Mucous membranes and tissues with a high oxygen demand, like nervous and cardiac tissues are most susceptible tissues in exposure to hydrogen sulfide. In addition, sulfide also seems to act on the respiratory drive through other mechanisms such as suppression of synaptic activity, inhibition of monoamine oxidase, a direct action on respiratory centers in the brain, and stimulation of the glutamate receptors in the brain. The hydrosulfide anion also forms a complex with methemoglobin and creates sulfmethemoglobin. On the other hand, hydrosulfide can be produced endogenously, particularly in mammalian cells, through an enzymatic pathway and in a smaller part via a nonenzymatic pathway. Among enzymes involved in hydrosulfide production, cystathionine- synthase and cystathionine-lyase have been investigated extensively; both use vitamin B6 as a cofactor. Captopyruvate sulfurtransferase along with cysteine aminotransferase are involved in transsulfuration and reverse transsulfuration pathways in different capacities and utilize specific substrates. Of course, the regulation mechanisms for the expression and activities of these hydrosulfide-generating enzymes under physiological or pathophysiological conditions needs more research. These enzymes are differentially expressed in neuronal, immune, cardiovascular, renal, gastrointestinal, reproductive, respiratory, liver, and endocrine systems and affect the functions of these systems through production of hydrosulfide. Meanwhile, different molecular targets, such as different ion channels and signaling proteins, mediate physiological functions of hydrogen sulfide. Alternations of hydrosulfide metabolism lead to an array of pathological disturbances in the form of hypertension, diabetes, cirrhosis, atherosclerosis, heart failure, inflammation, sepsis, erectile dysfunction, asthma, and neurodegenerative disease.

Hydrogen sulfide is flammable in air in the range of 4.3 to 45.5% (NFPA rating = 4). Combustion products (sulfur oxides) are also toxic by inhalation. In the event of a hydrogen sulfide fire, stop the flow of gas if possible without risk of harmful exposure and let the fire burn itself out.

6%

Strong rotten egg odor detectable at 0.001 to 0.1 ppm (mean = 0.0094 ppm); olfactory fatigue occurs quickly at high concentrations

Sweetish taste

pKa1= 6.90, pKa2 = 13.48(25℃)

7(at 25℃)

1.0×10-3mol/(m3Pa) at 25℃, Burkholder et al. (2019)

Highly flammable; a flame can very easily flash back to the source of leak. Soluble in water to a maximum of 0.4% by mass at room temperature .

HYDROGEN SULFIDE reacts as an acid and as a reducing agent. Explodes on contact with oxygen difluoride, bromine pentafluoride, chlorine trifluoride, dichlorine oxide, silver fulminate. May ignite and explode when exposed to powdered copper in oxygen [Mertz, V. et al., Ber., 1880, 13, p. 722]. May react similarly with other powdered metals. Ignites on contact with metal oxides and peroxides (barium peroxide, chromium trioxide, copper oxide, lead dioxide, manganese dioxide, nickel oxide, silver oxide, silver dioxide, thallium trioxide, sodium peroxide, mercury oxide, calcium oxide) [Mellor, 1947, vol. 10, p. 129, 141]. Ignites with silver bromate, lead(II) hypochlorite, copper chromate, nitric acid, lead(IV) oxide and rust. May ignite if passed through rusty iron pipes [Mee, A. J., School Sci. Rev., 1940, 22(85), p. 95]. Reacts exothermically with bases. The heat of the reaction with soda lime, sodium hydroxide, potassium hydroxide, barium hydroxide may lead to ignition or explosion of the unreacted portion in the presence of air / oxygen [Mellor, 1947, vol. 10, p. 140].

260 °C

2-8°C

2.3

UN 1053 2.3

2

F+,T+,N,F

9-16-36-38-45-61-28-26

MX1225000

F+,T+,N,F

cylinders of hydrogen sulfide should be stored and used in a continuously ventilated gas cabinet or fume hood. Local fire codes should be reviewed for limitations on quantity and storage requirements.

Explosive when mixed with air

Stable. Highly flammable. May form explosive mixture with air. Note wide explosive limits. Incompatible with strong oxidizing agents, many metals. May react violently with metal oxides, copper, fluorine, sodium, ethanal.

P210, P260, P271, P273, P284, P304+P340, P310, P320, P377, P381, P391, P403, P403+P233, P405, P501

Highly flammable, dangerous fire risk, explosive limits in air 4.3–46%. Toxic by inhalation, strong irritant to eyes and mucous membranes.

Hydrogen sulfide is incompatible with strong oxidizers. It will attack many metals, forming sulfides. Liquid hydrogen sulfide will attack some forms of plastics, rubber, and coatings. H2S reacts violently with a variety of metal oxides, including the oxides of chromium, mercury, silver, lead, nickel, and iron.

UN 1053

Compound is heavier than air and may travel a considerable distance to source of ignition and flash back. HYDROGEN SULFIDE forms explosive mixtures with air over a wide range. Also reacts explosively with bromine pentafluoride, chlorine trifluoride, nitrogen triiodide, nitrogen trichloride, oxygen difluoride, and phenyl diazonium chloride. When heated to decomposition, HYDROGEN SULFIDE emits highly toxic fumes of oxides of sulfur. Incompatible with many materials including strong oxidizers, metals, strong nitric acid, bromine pentafluoride, chlorine trifluoride, nitrogen triiodide, nitrogen trichloride, oxygen difluoride and phenyl diazonium chloride. Avoid physical damage to containers; sources of ignition; storage near nitric acid, strong oxidizing materials, and corrosive liquids or gases.

moderately

Hydrogen sulfide is a colorless, flammable compressed liquid gas with a characteristic odor of rotten eggs. The solubility of hydrogen sulfide in water is 3980 mg l-1at 20 ℃ and it is soluble in certain polar organic solvents, notably methanol, acetone, propylene carbonate, sulfolane, tributyl phosphate, various glycols and glycol ethers, gasoline, kerosene, crude oil, and carbon disulfide. The calculated vapor pressure at 21.9 ℃ is 1929 Pa. Boiling point and melting point of the substance are-60.33 ℃ and-85.49 ℃, respectively. Based on the estimated Henry’s law constant of 468 atm mol-1for hydrogen sulfide, volatilization from water and soil is high.

The acute toxicity of hydrogen sulfide by inhalation is moderate. A 5-min exposure to 800 ppm has resulted in death. Inhalation of 1000 to 2000 ppm may cause coma after a single breath. Exposure to lower concentrations may cause headache, dizziness, and upset stomach. Low concentrations of H2S (20 to 150 ppm) can cause eye irritation, which may be delayed in onset. Although the odor of hydrogen sulfide is detectable at very low concentrations, it rapidly causes olfactory fatigue at higher levels, and therefore is not considered to have adequate warning properties. Hydrogen sulfide has not been shown to be carcinogenic or to have reproductive or developmental effects in humans

Hydrogen sulphide (H2S) is a colorless, poisonous, flammable gas with an odor of rotting eggs. It is found in cesspools and mines and is a by-product of decomposed substances containing sulphur. It is one of the gaseous end-products of the reduction of sulphate in highly degraded paddy fields. Hydrogen sulphide is also produced in the laboratory for use as an analytical reagent.