The hydrogen sulfide or hydrogen sulfide is a gas formed by the union of a sulfur atom (S) and two hydrogen atoms (H). Its chemical formula is HtwoS. Also known as hydrogen sulfide gas. It is a colorless gas whose odor is evident in rotten eggs.
It is present in volcanoes and sulphurous hot springs, in natural gas and in crude oil. It is also formed during the anaerobic decomposition (without oxygen) of plant and animal organic matter. It occurs naturally in the mammalian body, through the action of certain enzymes on cysteine, a non-essential amino acid.
Aqueous solutions of HtwoS are corrosive to metals such as steel. The HtwoS is a reducing compound that, when reacting with SOtwo , oxidizes to elemental sulfur while reducing to SOtwo also sulfur.
Despite being a highly toxic and fatal compound for humans and animals, its importance in a series of important processes in the body has been studied for some years..
Regulates a series of mechanisms related to the generation of new blood vessels and the functioning of the heart.
Protects neurons and has been thought to act against diseases such as Parkinson's and Alzheimer's.
Due to its chemical reducing capacity, it can combat oxidant species, thus acting against cellular aging. Due to these reasons, the possibility of producing drugs that when given to patients can be released slowly into the body is being studied..
This would serve to treat pathologies such as ischemia, diabetes and neurodegenerative diseases. However, its mechanism of action and its safety have yet to be thoroughly investigated..
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The H moleculetwoS is analogous to that of water, that is, they are similar in shape since the hydrogens are located at an angle with the sulfur.
Sulfur in the HtwoS has the following electronic configuration:
1stwo, 2stwo 2 P6, 3stwo 3p6,
Well, it borrows one electron from each hydrogen to complete its valence shell..
- Hydrogen sulfide
- Hydrogen sulfide
- Sulfur hydride.
Colorless gas with a very unpleasant odor.
34.08 g / mol.
-85.60 ºC.
-60.75 ºC.
1.1906 g / L.
Moderately soluble in water: 2.77 volumes in 1 of water at 20ºC. Can be dislodged from aqueous solution completely by boiling.
When hydrogen sulfide is in aqueous solution, it is called hydrogen sulfide. It is a weak acid. It has two ionizable protons:
HtwoS + HtwoO ⇔ H3OR+ + HS-, Ka1 = 8.9 x 10-8
HS- + HtwoO ⇔ H3OR+ + Stwo-, Ka2 ∼ 10-14
The first proton ionizes slightly, as can be deduced from its first ionization constant. The second proton ionizes very little, but solutions of HtwoS contain some of the sulfide anion Stwo-.
If the solution of HtwoS is exposed to air, Otwo oxidizes to the sulfide anion and precipitates sulfur:
2 Stwo- + 4 h+ + ORtwo → 2 HtwoO + 2 S0↓ (1)
In the presence of chlorine Cltwo, bromine Brtwo and iodine Itwo the corresponding hydrogen halide and sulfur are formed:
HtwoS + Brtwo → 2 HBr + S0↓ (2)
Aqueous solutions of HtwoS are corrosive, produce sulfide stress cracking in high hardness steels. Corrosion products are iron sulfide and hydrogen.
The HtwoS reacts with oxygen in the air and the following reactions can occur:
2 htwoS + 3 Otwo → 2 HtwoO + 2 SOtwo (3)
2 htwoS + Otwo → 2 HtwoO + 2 S0↓ (4)
It reacts with various metals that displace hydrogen and forms the metal sulfide:
HtwoS + Pb → PbS + Htwo↑ (5)
In volcanic gases, HtwoS and SOtwo, which react with each other and solid sulfur is formed:
HtwoS + SOtwo → 2 HtwoO + 3 S0↓ (6)
Hydrogen sulfide is not very stable, it decomposes easily when heated:
HtwoS → Htwo↑ + S0↓ (7)
This gas is found naturally in sulphurous or sulphurous hot springs, in volcanic gases, in crude oil and in natural gas..
When oil (or gas) contains significant traces of HtwoS is said to be "sour", in contrast to "sweet", which is when it does not contain it.
Small amounts of HtwoS in oil or gas are economically detrimental because a scrubbing plant must be installed to remove it, both to prevent corrosion and to make the waste gas safe for domestic use as a fuel.
It is produced whenever organic matter containing sulfur decomposes under anaerobic conditions (absence of air), such as human, animal and plant waste.
Bacteria present in the mouth and in the gastrointestinal tract produce it from the degradable materials contained in plants or animal proteins..
Its characteristic smell makes it noticeable in rotten eggs.
The HtwoS is also produced in certain industrial activities, such as oil refineries, coke ovens, paper mills, tanneries, and in food processing.
The HtwoEndogenous S can be produced in mammalian tissues, including humans, by two pathways, one enzymatic and one non-enzymatic.
The non-enzymatic pathway consists of the reduction of elemental sulfur S0 to HtwoS by oxidation of glucose:
2 C6H12OR6 (glucose) + 6 S0 (sulfur) + 3 HtwoO → 3 C3H6OR3 + 6 htwoS + 3 COtwo (8)
The enzymatic pathway consists of the production of HtwoS from L-cysteine, which is an amino acid synthesized by the body. The process is ensured by several enzymes, such as cystathionine-β-synthase and cystathionine-γ-lyase, among others..
Hydrogen gas (Htwo) and the element sulfur (S) do not react at normal ambient temperatures, but above these they begin to combine, with 310 ºC being the optimum temperature.
However, the process is too slow, so other methods are used to obtain it, including the following.
Metal sulfides (such as ferrous sulfide) are reacted with acids (such as hydrochloric) in dilute solution.
FeS + 2 HCl → FeCltwo + HtwoS ↑ (9)
In this way, the gas HtwoS which, given its toxicity, must be collected safely.
Storage and transportation in large quantities of HtwoS separating from natural gas by amine scrubbing is difficult, so the Claus process is used to convert it into sulfur.
In this process two reactions occur. In the first the HtwoS reacts with oxygen to give SOtwo, as mentioned above (see reaction 3).
The second is an iron oxide catalyzed reaction where SOtwo is reduced and the HtwoS oxidizes, and both produce sulfur S (see reaction 6).
In this way, sulfur is obtained which can be easily stored and transported, as well as destined for multiple uses..
The HtwoEndogenous S is the one that occurs naturally in the body as part of normal metabolism in humans, mammals and other living beings.
Despite its longstanding reputation as a toxic and poisonous gas associated with the decomposition of organic matter, several recent studies from the 2000s to the present have determined that HtwoEndogenous S is an important regulator of certain mechanisms and processes in the living being.
The HtwoS has high lipophilicity or affinity towards fats, so it crosses cell membranes easily, penetrating all types of cells.
In mammals, hydrogen sulfide promotes or regulates a series of signals that regulate metabolism, cardiac function, and cell survival..
It has a powerful effect on the heart, blood vessels and circulating elements of the blood. Modulates cell metabolism and mitochondrial function.
Defends the kidneys from damage caused by ischemia.
It plays an important role as a protective factor against damage to the gastric mucosa. It is estimated that it may be an important mediator of gastrointestinal motility.
It is likely involved in the control of insulin secretion.
It also acts in important functions of the central nervous system and protects neurons from oxidative stress.
It is estimated that it can protect against neurodegenerative diseases such as Parkinson's, Alzheimer's and Hungtinton's disease.
Protects photoreceptor cells in the retina from light-induced degeneration.
The HtwoSince it is a reducing species, it can be consumed by a variety of oxidizing agents that circulate in the body. Combats oxidizing species such as reactive oxygen species and reactive nitrogen species in the body.
Limits free radical reactions through the activation of antioxidant enzymes that protect against the effects of aging.
The bioavailability of HtwoEndogenous S depends on certain enzymes involved in cysteine biosynthesis in mammals.
Some studies suggest that H-donor drug therapytwoS could be beneficial for certain pathologies.
For example, it could be useful in diabetic patients, since it has been observed that the blood vessels of diabetic animals improve with drugs that supply HtwoS exogenous.
The HtwoS supplied exogenously increases angiogenesis or blood vessel formation, so it could be used for the treatment of chronic ischemic diseases.
Drugs are being devised that can release HtwoS slowly to be able to act beneficially on various diseases. However, the efficacy, safety and mechanisms of its action have yet to be investigated..
The HtwoS is a fatal poison if inhaled neat or even diluted 1 part of gas in 200 parts of air. Birds are very sensitive to HtwoS and die even in dilution of 1 in 1500 parts of air.
The HtwoS is a potent inhibitor of certain enzymes and oxidative phosphorylation processes, leading to cell suffocation. Most people smell it at concentrations greater than 5 ppb (parts per billion). Concentrations of 20-50 ppm (parts per million) are irritating to the eyes and respiratory tract.
An inhalation of 100-250 ppm for a few minutes can cause incoordination, memory disorders and motor disorders. When the concentration is around 150-200 ppm, olfactory fatigue or anosmia occurs, which means that afterwards the characteristic smell of H cannot be detected.twoS. If a concentration of 500 ppm is inhaled for 30 minutes, pulmonary edema and pneumonia can occur..
Concentrations of more than 600 ppm can be fatal within the first 30 minutes, as the respiratory system is paralyzed. And 800 ppm is the concentration that is immediately lethal to humans..
It should therefore be avoided that there are leaks of HtwoS in laboratories, premises or in any place or situation.
It is important to note that many deaths occur because people enter confined spaces to rescue co-workers or family members who have collapsed due to H poisoning.twoYes, passing them too.
It is a flammable gas.
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