Sulfur is one of the substances known to mankind from time immemorial. Even the ancient Greeks and Romans found various uses for it. Pieces of native sulfur were used to perform the ritual of expelling evil spirits. So, according to legend, Odysseus, returning to his home after long wanderings, first ordered it to be fumigated with sulfur. There are many references to this substance in the Bible.
In the Middle Ages, sulfur occupied an important place in the arsenal of alchemists. As they believed, all metals consist of mercury and sulfur: the less sulfur, the more noble. Practical interest in this substance in Europe increased in the 13th – 14th centuries, after the advent of gunpowder and firearms. The main supplier of sulfur was Italy.
Today, sulfur is used as a raw material for the production of sulfuric acid, gunpowder, in the vulcanization of rubber, in organic synthesis, and also for controlling agricultural pests. Sulfur powder is used in medicine as an external disinfectant.
Interaction of sulfur with simple substances
Sulfur reacts like oxidizer :
2Na + S = Na 2 S
How reducing agent :
Interaction of sulfur with complex substances
a) sulfur does not dissolve in water and is not even wetted by water;
b) how the reducing agent sulfur interacts with ( , ) when heated:
S + 2H 2 SO 4 = 3SO 2 + 2H 2 O
S + 2HNO3 = H2SO4 + 2NO
S + 6HNO 3 = H 2 SO 4 + 6NO 2 + 2H 2 O
c) exhibiting the properties of both an oxidizing agent and a reducing agent, sulfur enters into disproportionation reactions (self-oxidation-self-reduction) with solutions when heated:
3S + 6NaOH = 2Na2S + Na2SO3 + 3H2O
Hydrogen sulfide and hydrogen sulfide acid
a) H 2 S + CaO = CaS + H 2 O
b) H 2 S + NaOH = NaHS + H 2 O
c) CuSO 4 + H 2 S = CuS↓ + H 2 SO 4
d) Ca + H 2 S = CaS + H 2
A qualitative reaction to hydrosulfide acid and its soluble salts (i.e., to the sulfide ion S 2-) is their interaction with soluble salts. In this case, a black precipitate of lead (II) sulfide PbS is released:
Na 2 S + Pb(NO 3) 2 = PbS↓ + 2NaNO 3
Redox properties
In redox reactions, both gaseous hydrogen sulfide and hydrosulfide acid exhibit strong reducing properties, since the sulfur atom in H2S has the lowest oxidation state - 2, and therefore can only be oxidized. It oxidizes easily:
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What is hydrogen sulfide?
HYDROGEN SULPHIDE, H 2 S, (hydrogen sulfide, hydrogen sulfide) is a colorless flammable gas with a pungent odor, boiling point 60.35 °C. Aqueous solution - hydrosulfide acid. Hydrogen sulfide is often found in oil and gas fields.
Hydrogen sulfide H 2 S is toxic: acute human poisoning occurs at concentrations of 0.2–0.3 mg/m 3 , concentrations above 1 mg/m 3 are fatal. Hydrogen sulfide H 2 S is an aggressive gas that provokes acid corrosion, which in this case is called hydrogen sulfide corrosion. When dissolved in water, it forms a weak acid which can cause pitting in the presence of oxygen or carbon dioxide.
In this regard, without modern gas treatment stations and desulfurization modules, hydrogen sulfide can cause severe damage to people. The maximum permissible concentration of hydrogen sulfide in the air of the working area is 10 mg/m3, and in a mixture with C1–C3 hydrocarbons it is equal to 3 mg/m3.
Without hydrogen sulfide treatment stations, a variety of equipment in the oil, energy, transport and gas processing industries seriously suffers and fails.
What happens to metals if hydrogen sulfide is not removed?
Hydrogen sulfide - H 2 S - total metal corrosion
Hydrogen sulfide reacts with almost all metals, forming sulfides, which act as a cathode in relation to iron and form a galvanic couple with it. The potential difference of this pair reaches 0.2–0.48 V. The ability of sulfides to form microgalvanic pairs with steel leads to rapid destruction of process equipment and pipelines.
It is extremely difficult to combat hydrogen sulfide corrosion: despite the addition of acid corrosion inhibitors, pipes made from special grades of stainless steel quickly fail. And even sulfur obtained from hydrogen sulfide can be transported in metal tanks for a limited period of time, since the tanks are prematurely destroyed due to hydrogen sulfide dissolved in sulfur. In this case, the formation of polysulfanes HS n H occurs. Polysulfanes are more corrosive elements than hydrogen sulfide.
Hydrogen sulfide, when added to unsaturated compounds, forms mercaptans, which are an aggressive and toxic part of sulfur compounds - chemical poisons. It is they that significantly worsen the properties of catalysts: their thermal stability, intensify the processes of resin formation, loss and deposition of slag, sludge, and sediment, which causes passivation of the surface of the catalysts, and also enhance the corrosive activity of the material of technological devices.
H 2 S significantly enhances the process of hydrogen penetration into steel. If during corrosion in acidic environments the maximum proportion of hydrogen diffusing into steel is 4% of the total amount of reduced hydrogen, then in hydrogen sulfide-containing solutions this value reaches 40%.
The presence of oxygen in the gas significantly accelerates corrosion processes. It was experimentally found that the most corrosive gas is the one in which the ratio of oxygen to hydrogen sulfide is 114:1. This attitude is called critical.
The presence of moisture in the gas leads to corrosion of the metal, but the simultaneous presence of H 2 S, O 2 and H 2 O is the most unfavorable from the point of view of corrosion.
The corrosive effect of these impurities on metal increases sharply with increasing pressure.
The rate of corrosion of gas pipelines is directly proportional to the pressure of the gas passing through this gas pipeline. At pressures up to 20 atm. and wet gas, even traces of hydrogen sulfide 0.002–0.0002% vol. are enough to cause significant corrosion damage to the pipe metal, limiting the service life of the gas pipeline to 5–6 years.
Due to the corrosive effects of hydrogen sulfide present in gases, the service life of power generation equipment (GPES - GTU) and equipment during gas production, transportation, processing and use is significantly reduced.
In field conditions, pipes, valves, combustion chambers and pistons of power plants, gas meters, compressors, and refrigerators are subject to particularly high levels of corrosion.
A significant portion of hydrogen sulfide reacts with metal and can be deposited in the form of corrosion products on the valves of power plants, compressors, on the internal walls of equipment, communications and main gas pipelines.
Relevance of the problem of gas purification from hydrogen sulfide
The urgency of the problem of purifying gas from hydrogen sulfide is enhanced by the requirements to ensure environmental safety when developing sulfur deposits and reducing harmful emissions into the atmosphere.
At the same time, special attention is paid to improving existing and developing new desulfurization technologies that eliminate emissions of toxic hydrogen sulfide and its combustion products into the environment.
Despite all the listed disadvantages, hydrogen sulfide is a valuable chemical raw material, since a huge amount of inorganic and organic compounds can be obtained from it.
If they say that he is weak, it means that illness or hunger has come, in general, adversity. In chemistry everything is different. Let's consider weak hydrogen sulfide. It is weak not because it is ready to disintegrate or die, but, on the contrary, because of its unwillingness to dissociate.
This is the name given to the process of dissolution in water, separation into hydronium ion and anion. Hydrogen sulfide dissociates by only 0.011%, and in two stages. In the first of them, the degree of decay does not exceed 0.005%.
So, it is quite resistant, “takes a hit.” However, this is by human standards. In chemistry everything is different. Let's dive into its world by continuing to study the properties of hydrogen sulfide.
Properties of hydrogen sulfide acid
The heroine's resilience is relative. Not wanting to completely dissolve in water, the compound disintegrates under the influence of oxygen. It oxidizes hydrosulfide acid. Formula it looks like this: - Н 2 S. Н in it - , S - . So, the latter “breaks out” of the formula during oxidation. The connection breaks down.
In fact, hydrosulfide acid is an aqueous solution of gas. Hydrogen sulfide is known to smell like rotten eggs and is toxic. the substance does not. Neither do indicator papers that have been in hydrosulfide acid. Property this is another indicator of a weak connection. Strong ones color litmus in tones.
Characteristics of hydrogen sulfide acid comes down not only to slow dissolution in water. Other reactions with the heroine of the article also take place slowly. In relation to human character, this is rather laziness than weakness.
For example, hydrogen sulfide solution reacts reluctantly with metals. The explanation for this is the low concentration of positive hydrogen ions. Their deficiency is associated with a low degree of dissociation.
Of the metals, the heroine of the article interacts only with those in the voltage series up to H2. Such elements are capable of displacing hydrogen from solution. Interaction can lead to the formation hydrosulfide salts.
It is completely insoluble in water. The replica concerns sulfides. This is one of the types formed with the participation of hydrogen sulfide compounds. The second type is hydrosulfides. They are formed during the reaction with alkaline and alkaline earth compounds and are soluble.
When interacting with alkaline earth metals, hydrogen sulfide also reacts with alkalis. The heroine of the article acts as a reducing agent, that is, she donates electrons. It turns out that the properties of the connection are typical for the weak type.
The other thing is ambiguous. Being a solution of poisonous hydrogen sulfide, the heroine of the article is only relatively dangerous. Due to the low concentration of the original substance, it becomes a medicine. We will tell you where and how it is used in the next chapter.
Application of hydrogen sulfide acid
Dissociation of hydrosulfide acid to a solution with a saturation of thousandths of a percent allows the compound to be used for medicinal purposes. They are usually organized in areas where groundwater containing hydrogen sulfide emerges. The smell of rotten eggs is tolerated for the sake of getting rid of skin ailments, rehabilitation of the system, and treatment of insomnia.
Hydrogen sulfide baths improve blood flow, which means they have a beneficial effect on the entire body. Moving faster through the vessels, the blood does not stagnate and more quickly supplies the organs with the elements they need. Metabolism accelerates, leading to cleansing of toxins. For the overall effect of rejuvenation.
“On the face” is used in its literal meaning. Cosmetologists use hydrogen sulfide solution for lifting procedures. In addition to tightening, you can get rid of cellulite and acne. Local application of the solution has fewer contraindications than baths.
Doctors note that baths with hydrogen sulfide are not taken at home or, in general, in enclosed spaces. The concentration of vapors emanating from water may exceed permissible limits.
In sanatoriums, they try to place pools in the open air. Hot springs. Therefore, it is pleasant to swim in them even in winter. There are a number of hydrogen sulfide resorts, for example, near the city of Severobaikalsk.
Doctors supervising the guests also recommend the heroine of the article as a cure for ailments of the genitourinary system. True, the procedures are contraindicated for pregnant and lactating women. But for those who want to become a parent, baths with hydrogen sulfide will not harm.
In the west of the country, hydrogen sulfide is formed along the Black Sea shelf. True, there the compound forms at a depth of about 150 meters, emerging as bubbles into the shallow water.
If temporary procedures in a gas atmosphere are acceptable, then prolonged inhalation of hydrogen sulfide leads to a loss of the ability to smell. This is the result of paralysis of the olfactory nerve.
How to recognize hydrogen sulfide acid in the air at low concentrations, in the absence of obvious odor? Only it will help. She is also poisonous, but there is no other way. It is moistened in the reagent. In an atmosphere containing at least 0.0000001% hydrogen sulfide, the leaf will become coated.
Preparation of hydrogen sulfide acid
Since it is a solution of hydrogen sulfide, it is worth asking about its production. A popular way to use sulfide. Natural minerals are used as the latter. There are several sulfides in the interior of the planet. The most famous is perhaps. Its formula: - FeS 2.
The reaction between sulfide and is violent, with active gas evolution. Accordingly, interaction is carried out in isolated rooms, using protective clothing.
Industrialists often go the other way. Hydrogen sulfide is a by-product of many industries. All that remains is to extract the substance from industrial gases, the purification of which, anyway, is the direct responsibility of enterprises.
Then, hydrogen sulfide is dissolved in water. The liquid is heated. This makes dissociation more successful. The heroine of the article is ready for use or sale. Let's find out the price tags.
Hydrosulfide acid price
Since in everyday life the heroine of the article is needed only for water procedures, the form of sale of the compound is reduced to hydrogen sulfide baths. Example: - “Matsesta” product. It is sold in pharmacies, like other drugs in the group.
“Matsesta” is sold in bags and added to a bath of water at a temperature of 37-38 degrees Celsius. The drug is thoroughly stirred and immersed for 5-15 minutes. The pleasure costs about 300 per package, that is, one procedure.
The remark about the dangers of taking hydrogen sulfide baths at home has not been canceled. But manufacturers play it safe by choosing the optimal, safe concentration. With it, do not apply it within 15 minutes.
For laboratory needs and industrial production, it makes no sense to pay for water with a minimal proportion of hydrogen sulfide. It is more convenient to organize the supply of liquefied gas in cylinders and do it yourself. The product is specific, demand is limited. Therefore, there are few offers, and gas cylinders are usually negotiable.
Hydrogen sulfide (H 2 S) - very carcinogenic, toxic gas. It has a sharp, characteristic smell of rotten eggs.
Obtaining hydrogen sulfide.
1. In the laboratory H 2 S obtained by reaction between sulfides and dilute acids:
FeS + 2 HCl = FeCl 2 + H 2 S,
2. Interaction Al 2 S 3 with cold water (the resulting hydrogen sulfide is purer than with the first production method):
Al 2 S 3 + 6H 2 O = 2Al(OH) 3 + 3H 2 S.
Chemical properties of hydrogen sulfide.
Hydrogen sulfide H2S - a covalent compound that does not form hydrogen bonds like a molecule H 2 O. (The difference is that the sulfur atom is larger and more electronegative than the oxygen atom. Therefore, the charge density of sulfur is lower. And due to the lack of hydrogen bonds, the boiling point H 2 S higher than that of oxygen. Also H 2 S poorly soluble in water, which also indicates the absence of hydrogen bonds).
H 2 S + Br 2 = S + 2HBr,
2. Hydrogen sulfide H 2 S- a very weak acid, dissociates stepwise in solution:
H 2 S ⇆ H + + H.S. - ,
H.S. - ⇆ H + + S 2- ,
3. Interacts with strong oxidizing agents:
H 2 S + 4Cl 2 + 4H 2 O = H 2 SO 4 + 8HCl,
2 H 2 S + H 2 SO 3 = 3 S + 3 H 2 O,
2 FeCl 3 + H 2 S = 2 FeCl 2 + S + 2 HCl,
4. Reacts with bases, basic oxides and salts, forming acidic and moderate salts (hydrosulfides and sulfides):
Pb(NO 3) 2 + 2S = PbS↓ + 2HNO 3.
This reaction is used to detect hydrogen sulfide or sulfide ions. PbS- black sediment.
