- (hydrogen sulfide) H2S, a colorless gas with a rotten egg odour; tmelt? 85.54 .С, tboil? 60.35 .С; at 0 .C it liquefies under a pressure of 1 MPa. Reducing agent. By-product of oil refining, coal coking, etc.; formed by decomposition... Big Encyclopedic Dictionary
- (H2S), colorless, poisonous gas with a smell of rotten eggs. Formed during decay processes, found in crude oil. Obtained by the action of sulfuric acid on metal sulfides. Used in traditional QUALITATIVE ANALYSIS. Properties: temperature ... ... Scientific and technical encyclopedic dictionary
Hydrogen sulfide, hydrogen sulfide, pl. no, husband. (chem.). A gas formed during the decay of protein substances, emitting the smell of rotten eggs. Explanatory Dictionary of Ushakov. D.N. Ushakov. 1935 1940 ... Explanatory Dictionary of Ushakov
Hydrogen sulfide, a, husband. A colorless gas with a pungent, unpleasant odor resulting from the decomposition of proteins. | adj. hydrogen sulfide, oh, oh. Explanatory dictionary of Ozhegov. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Explanatory dictionary of Ozhegov
Exist., Number of synonyms: 1 gas (55) ASIS Synonym Dictionary. V.N. Trishin. 2013 ... Synonym dictionary
Colorless poisonous gas H2S with an unpleasant specific odor. Possesses slightly acidic properties. 1 liter C. at t 0 ° C and a pressure of 760 mm is 1.539 g. It is found in oils, in natural waters, in gases of biochemical origin, as ... ... Geological Encyclopedia
hydrogen sulfide- Hydrogen sulfide, H2S (molecular weight 34.07), a colorless gas with a characteristic smell of rotten eggs. A liter of gas under normal conditions (0°, 760 mm) weighs 1.5392 g. Temperature, boiling 62°, melting 83°; S. is part of gaseous secretions ... ... Big Medical Encyclopedia
hydrogen sulfide- — Biotechnology topics EN hydrogen sulfide … Technical Translator's Handbook
hydrogen sulfide- HYDROGEN SULFIDE, a, m A colorless gas with a sharp unpleasant odor, formed during the decomposition of protein substances and representing a combination of sulfur with hydrogen. Hydrogen sulfide is found in some mineral waters and therapeutic muds and is used ... ... Explanatory dictionary of Russian nouns
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DEFINITION
hydrogen sulfide It is a colorless gas with a characteristic odor of rotting protein.
It is slightly heavier than air, liquefies at -60.3 o C and solidifies at -85.6 o C. In air, hydrogen sulfide burns with a bluish flame, forming sulfur dioxide and water:
2H 2 S + 3O 2 \u003d 2H 2 O + 2SO 2.
If some cold object, such as a porcelain cup, is introduced into the hydrogen sulfide flame, the flame temperature drops significantly and hydrogen sulfide is oxidized only to free sulfur, which settles on the cup in the form of a yellow coating:
2H 2 S + O 2 \u003d 2H 2 O + 2S.
Hydrogen sulfide is highly flammable; its mixture with air explodes. Hydrogen sulfide is very toxic. Prolonged sighing of air containing this gas, even in small quantities, causes severe poisoning.
At 20° C., one volume of water dissolves 2.5 volumes of hydrogen sulfide. A solution of hydrogen sulfide in water is called hydrogen sulfide water. When standing in air, especially in the light, hydrogen sulfide water soon becomes cloudy from the sulfur released. This occurs as a result of the oxidation of hydrogen sulfide by atmospheric oxygen.
Obtaining hydrogen sulfide
At high temperatures, sulfur reacts with hydrogen to form hydrogen sulfide gas.
In practice, hydrogen sulfide is usually obtained by the action of dilute acids on sulphurous metals, for example, on iron sulfide:
FeS + 2HCl \u003d FeCl 2 + H 2 S.
More pure hydrogen sulfide can be obtained by hydrolysis of CaS, BaS or A1 2 S 3 . The purest gas is obtained by the direct reaction of hydrogen and sulfur at 600°C.
Chemical properties of hydrogen sulfide
A solution of hydrogen sulfide in water has the properties of an acid. Hydrogen sulfide is a weak dibasic acid. It dissociates in steps and mainly in the first step:
H 2 S↔H + + HS - (K 1 \u003d 6 × 10 -8).
Dissociation on the second stage
HS - ↔H + + S 2- (K 2 \u003d 10 -14)
proceeds to a very small extent.
Hydrogen sulfide is a strong reducing agent. Under the action of strong oxidizing agents, it is oxidized to sulfur dioxide or to sulfuric acid; the depth of oxidation depends on the conditions: temperature, pH of the solution, concentration of the oxidizing agent. For example, the reaction with chlorine usually proceeds to the formation of sulfuric acid:
H 2 S + 4Cl 2 + 4H 2 O \u003d H 2 SO 4 + 8HCl.
Medium salts of hydrogen sulfide are called sulfides.
The use of hydrogen sulfide
The use of hydrogen sulfide is rather limited, which is primarily due to its high toxicity. It has found application in laboratory practice as a precipitant for heavy metals. Hydrogen sulfide serves as a raw material for the production of sulfuric acid, elemental sulfur and sulfides
Examples of problem solving
EXAMPLE 1
| Exercise | Determine how many times heavier than air hydrogen sulfide H 2 S. |
| Solution | The ratio of the mass of a given gas to the mass of another gas taken in the same volume, at the same temperature and the same pressure, is called the relative density of the first gas over the second. This value shows how many times the first gas is heavier or lighter than the second gas. The relative molecular weight of air is taken equal to 29 (taking into account the content of nitrogen, oxygen and other gases in the air). It should be noted that the concept of "relative molecular weight of air" is used conditionally, since air is a mixture of gases. D air (H 2 S) = M r (H 2 S) / M r (air); D air (H 2 S) = 34/29 = 1.17. M r (H 2 S) = 2 × A r (H) + A r (S) = 2 × 1 + 32 = 2 + 32 = 34. |
| Answer | Hydrogen sulfide H 2 S is 1.17 times heavier than air. |
EXAMPLE 2
| Exercise | Find the hydrogen density of a mixture of gases in which the volume fraction of oxygen is 20%, hydrogen is 40%, and the rest is hydrogen sulfide H 2 S. |
| Solution | The volume fractions of gases will coincide with the molar fractions, i.e. with fractions of quantities of substances, this is a consequence of Avogadro's law. Find the conditional molecular weight of the mixture: M r conditional (mixture) = φ (O 2) × M r (O 2) + φ (H 2) × M r (H 2) + φ (H 2 S) × M r (H 2 S); |
Hydrogen sulfide can be formed in the body and affect the course of metabolic reactions. A change in its concentration leads to the development of pathologies. At the same time, an excess of this gas in the air is dangerous!
Hydrogen sulfide is a gas with an extremely unpleasant smell of rotting protein or, simply put, rotten eggs. It is released during the decomposition of organic matter. Hydrogen sulfide is heavier than air, so it can accumulate in ditches, ravines, pits and contaminated wells. They are also rich in volcanic gases. In industry, hydrogen sulfide is a by-product of oil and coal processing, wastewater treatment, the production of paints, cellophane, sugar, viscose, etc. What effect does it have on the body, read below.
The harm of hydrogen sulfide
Human contact with hydrogen sulfide is very dangerous. This gas is a strong poison. Once in the body, it turns into sulfate and blocks the respiratory enzyme cytochrome oxidase. At a low concentration of hydrogen sulfide in the air, the respiratory system is excited. So the human body seeks to compensate for the lack of oxygen.
With an increase in the content of this gas, a sharp depression of the respiratory system begins. At a hydrogen sulfide concentration of 1000 mg / m3 and above, a person will experience instant death.
The negative effect of hydrogen sulfide on the body is not limited to the suppression of tissue respiration. This gas easily reacts with iron ions contained in hemoglobin molecules. As a result, iron sulfide is formed, while the blood turns black and loses its ability to transport oxygen.
However, the harm of hydrogen sulfide for humans does not end there. Its detrimental effect on the nervous system has been proven. Excessive concentrations of this gas lead to excessive stimulation of neurons. Inhalation of hydrogen sulfide causes anxiety and depression. With prolonged contact, a person develops:
- mental disorders;
- sleep disorders;
- damage to the autonomic nervous system.
It is noteworthy that with prolonged exposure to low concentrations of hydrogen sulfide or short-term inhalation of air with a high content of this gas, the body ceases to perceive an unpleasant odor. This is due to the development of paralysis of the respiratory nerve.
Even low concentrations of hydrogen sulfide irritate the conjunctiva of the eyes and mucous membranes of the respiratory tract. As a result, a person may develop:
- rhinitis;
- bronchitis;
- salivation;
- keratoconjunctivitis.
Hydrogen sulfide poisoning is also accompanied by a decrease in blood pressure, increased heart rate, vomiting, dizziness and headache.
The positive role of hydrogen sulfide
Nevertheless, hydrogen sulfide can have a positive effect on the human body. It has been established that this gas is useful and even necessary for certain physiological processes. In microquantities, it is formed in the body, and this ability is genetically programmed. 
. Mutations of the gene that regulates the production of endogenous (internal) hydrogen sulfide lead to the development of atherosclerosis, hypertension, Alzheimer's and Parkinson's diseases.
Investigate the effect of this gas on the body began in 1998 with experiments on rats. Until now, many mechanisms of its action have not been fully disclosed, but the study continues. It is reliably known that hydrogen sulfide, like nitric oxide II (NO) and carbon monoxide (CO), is involved in the processes of vasodilation and transmission of nerve impulses.
Influence on the walls of blood vessels
Hydrogen sulfide, which is formed in the body, is able to relax the smooth muscles of blood vessels. As a result, their clearance increases. When blood vessels dilate, pressure decreases and blood circulation improves. Thus, there is reason to believe that endogenous hydrogen sulfide is struggling with hypertension. In addition, vasodilation improves erection. Hydrogen sulfide has been shown to actually have this effect.
Also, this gas inhibits the development of atherosclerosis and the narrowing of the lumen of the vessels caused by it. As is known, cholesterol plaques are deposited on the surface of the vascular walls only after they have been damaged. Hydrogen sulfide has an anti-inflammatory effect. It protects the walls of blood vessels from calcification and the associated loss of elasticity. This increases their resistance to damage.
In addition to improving the vascular wall, hydrogen sulfide protects it from the destructive effects of metabolites and active oxygen - metabolic by-products. Entering into chemical reactions with such compounds, it binds and neutralizes them. Hydrogen sulfide metabolites are excreted by the kidneys in the urine.
Effect on the nervous system
The human body is a system in which cascades of chemical reactions continuously occur with the formation of toxic by-products. The most dangerous are free radicals, which actively damage protein and lipid molecules. Their effect on nerve cells is especially detrimental.
Hydrogen sulfide, reacting with free radicals and neutralizing them, protects all organs and the brain, in particular, from damage.
Scientists have proven that in patients suffering from Alzheimer's and Parkinson's diseases, the content of hydrogen sulfide in the brain tissues is below normal. The introduction of a derivative of this gas - NaHS salt - causes improvement in these pathologies. However, such experiments have so far been carried out only on mice.
In addition, it was found that hydrogen sulfide increases the activity of cells that provide nutrition to neurons - astrocytes. It is also known that this gas stimulates the work of the parts of the brain responsible for memory. The data obtained will be used in the development of drugs intended for the treatment of Parkinson's and Alzheimer's diseases.
Impact on other systems
Recent studies by Chinese scientists have shown that endogenous hydrogen sulfide is a kind of "youth gas". It increases the activity of the gene that is responsible for life expectancy. At the same time, the body begins to synthesize more of its own antioxidants, in parallel, substances are formed that indirectly reduce blood pressure.
Hydrogen sulfide affects the production of the sirtuin protein, which inhibits oxidative reactions. Increased production of this enzyme leads, according to scientists, to slow down aging.
Endogenous hydrogen sulfide is useful for the regeneration of cardiomyocytes. It reduces the degree of heart damage during ischemia and infarction, improves cell regeneration. According to some reports, hydrogen sulfide has anti-inflammatory properties. This gas has been shown to prevent gastric mucosal lesions resulting from the misuse of non-steroidal anti-inflammatory drugs (Ibuprofen, Aspirin, Diclofenac).
In nature, there are no exclusively harmful or beneficial substances. Everything is good in moderation. Useful compounds in large quantities can poison the body, and small concentrations of harmful substances are often useful. Same with hydrogen sulfide. This gas is known as a strong poison, but without it, the flow of many metabolic processes is simply impossible.
And, although studies of the role of hydrogen sulfide in the human body were started not so long ago and are still far from complete, it is already clear that without this gas the normal operation of many organs and systems is impossible.
Recently, a strong release of hydrogen sulfide occurred at the Yadrovo landfill in Volokolamsk. As a result, about 50 children sought medical help with complaints of nausea and dizziness. In connection with this news, we decided to talk about such a substance as hydrogen sulfide.
Most of us do not even realize that hydrogen sulfide is encountered quite often. Almost everyone knows about hydrogen sulfide sources - water, which is sold in bottles in the public domain, as well as hydrogen sulfide baths, which we take on the recommendations of doctors or on our own initiative. Residents of the capital sometimes perfectly smell this substance. Is it harmful to us?
What is hydrogen sulfide
Hydrogen sulfide is a colorless gas that has a sweet taste and the smell of rotten eggs, we also learn from a textbook on a subject such as chemistry that it is hydrogen sulfide (H2S). It dissolves in water very poorly, but in alcohol, on the contrary, it is excellent. Heavy compared to air, lighter than water. Can this substance be harmful to health? Certainly! In large quantities, it is very poisonous and ignites easily, in small quantities it is safe to use, which is what doctors use. It normalizes the work of the heart, blood vessels, without it there is no erection, a very good antispasmodic, in addition to all this, it plays an important role in the functioning of the nervous system and memory. With a lack of this substance, a person is more likely to develop heart attacks, Alzheimer's and Parkinson's diseases. It enters not only through the respiratory system, but also through the pores of the skin, having a good effect on it.
How and where is it formed
Natural gas includes this substance in small quantities, is found in intestinal gases, the composition of associated petroleum gas. Predominates in large numbers in volcanic gases. It is formed in places where proteins with cysteine or methionine rot in a metropolis - due to weak treatment facilities or idle facilities of enterprises that use hydrogen sulfide in production or those who have it as a by-product. The release of gas at such enterprises is accompanied by an unpleasant smell of rotten eggs. What harm does he do? Does it cause any disease?
Under what circumstances does poisoning occur?
You can feel the smell of hydrogen sulfide only when it is only up to 0.03 μg / m 3 in the air. If the volume of this substance exceeds the permissible limit, then we do not smell it. And at a concentration of about 1000 mcg / cu. m of air, almost instant death occurs. Intermediate amounts lead to various diseases, for example, 75 mcg / cu. m - the development of keratoconjunctivitis, bronchitis, which is accompanied by a characteristic cough; 375 mcg/cu. m - pulmonary edema. Hydrogen sulfide is so dangerous in the air.
Consequences of constant (prolonged) contact with hydrogen sulfide
It is clear that the gas in the air does not please everyone. But most of all, he delivers trouble to miners, oil workers, metallurgists, workers in the chemical and sugar industries, processing plants, factories producing cellophane and viscose. They, according to doctors, manifest:
- chronic keratoconjunctivitis;
- frequent bronchitis, rhinitis;
- gastrointestinal disorders;
- frequent headaches;
- insomnia;
- dizziness, constant loss of strength;
- increased sweating;
- hypotension;
- poor appetite;
- eczema, dermatitis;
- anisocytosis, monocytosis, anemia.
After some time, people get used to the characteristic smell of hydrogen sulfide, but health, of course, does not improve.
Degrees of poisoning
Air containing hydrogen sulfide can be very harmful. The following degrees of poisoning are distinguished:
- light. Indications: burning, pain in the eyes; tearing; irritation from light sources; gagging; cough; runny nose;
- average. To what is listed above are added: pain, dizziness; severe vomiting; severe weakness or agitation; impaired coordination of movements;
- heavy. Indications: cyanotic complexion; vomit; suffocation; failure of the heart rhythm.
To all of the above, we add that severe hydrogen sulfide poisoning can cause coma, and sometimes death.
Actions in case of poisoning
We told what hydrogen sulfide is and how exactly it can harm our body, but what actions are needed if poisoning does occur?
At light the degree of poisoning a person must be provided with: clean fresh air; peace; analgesics; lotions with boric acid; novocaine with adrenaline - drip into the eyes; vitamins and iron supplements. At middle and severe degree of the patient must be sent to the hospital.
With cyanosis, heart failure, heart rhythm failures, caffeine, cordiamine, norepinephrine are administered. In a coma, resuscitation therapy is carried out.
Means of protection
The main part of hydrogen sulfide decomposes into sulfur and sulfates, then excreted by the kidneys. With exhalation, about 7% of the gas leaves. Workers working with this dangerous gas are highly discouraged from neglecting their protective equipment, they must systematically undergo medical examinations and follow all safety regulations. At such enterprises, it is necessary to control the tightness of production processes and compliance with environmental requirements.
In an apartment, you can also measure the content of hydrogen sulfide using special devices, for example, ANKAT-7631, it is small and elementary in use. You can also contact the relevant laboratories.
Hydrogen sulfide in the Black Sea
It certainly poses a danger if it is at a depth of 150 meters or more - there is nothing there but microbes. Hydrogen sulfide does not float, does not allow it to do this, according to scientists, the high pressure of the upper layers. But sometimes bubbles are released, harming the inhabitants of the underwater world. But a person should not be afraid of these gases, they are safe for us.
hydrogen sulfide (H 2 S) is a highly carcinogenic, toxic gas. It has a strong characteristic smell of rotten eggs.
Getting hydrogen sulfide.
1. In the laboratory H 2 S obtained during the 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 more pure than in the first method of production):
Al 2 S 3 + 6H 2 O \u003d 2Al (OH) 3 + 3H 2 S.
Chemical properties of hydrogen sulfide.
hydrogen sulfide H 2 S - 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 of 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 \u003d S + 2HBr,
2. Hydrogen sulfide H 2 S- very weak acid, dissociates stepwise in solution:
H 2 S ⇆ H + + HS - ,
HS - ⇆ H + + S 2- ,
3. Interacts with strong oxidizing agents:
H 2 S + 4Cl 2 + 4H 2 O \u003d 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, while forming acidic and medium 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.
