DEFINITION
Hydrosulphuric acid(hydrogen sulfide, monosulfan) in normal conditions is a colorless gas.
Thermally unstable. Poorly soluble in cold water. A saturated solution (0.1 M) is called "hydrogen sulfide water", which becomes cloudy when exposed to air. Shows weak acidic properties. In OVR, it is a strong reducing agent.
Chemical formula of hydrosulfide acid
Chemical formula hydrosulfide acid H 2 S. It shows that this molecule contains two hydrogen atoms (Ar = 1 amu) and one sulfur atom (Ar = 32 amu). According to the chemical formula, you can calculate the molecular weight of hydrosulfide acid:
Mr(H 2 S) = 2×Ar(H) + Ar(S);
Mr(H 2 S) \u003d 2 × 1 + 32 \u003d 2 + 32 \u003d 34.
Graphical (structural) formula of hydrosulfide acid
The structural (graphical) formula of hydrosulfide acid is more visual. It shows how the atoms are connected to each other inside the molecule (Fig. 1).
Rice. 1. The structure of the hydrogen sulfide molecule, indicating the bond angle between bonds and the length of chemical bonds.
Ionic formula
Hydrosulfuric acid is an electrolyte, i.e. in aqueous solution, it is able to dissociate into ions according to the following equation:
H 2 S ↔ 2H + + S 2-.
Examples of problem solving
EXAMPLE 1
| Exercise | Determine molecular formula a compound containing 49.4% potassium, 20.2% sulfur, 30.4% oxygen, if the relative molecular weight of this compound is 3.95 times the relative atomic mass of calcium. |
| Solution |
Let us denote the number of moles of elements that make up the compound as "x" (potassium), "y" (sulfur) and "z" (oxygen). Then, the molar ratio will look like this (values of relative atomic masses taken from Periodic table DI. Mendeleev, rounded up to integers): x:y:z = ω(K)/Ar(K) : ω(S)/Ar(S) : ω(O)/Ar(O); x:y:z= 49.4/39: 20.2/32: 30.4/16; x:y:z= 1.3: 0.63:1.9 = 2: 1: 3. Means the simplest formula compounds of potassium, sulfur and oxygen will look like K 2 SO 3 and molar mass 158 g/mol. Find the true molar mass of this compound: M substance \u003d Ar (Ca) × 3.95 \u003d 40 × 3.95 \u003d 158 g / mol. To find the true formula organic compound find the ratio of the obtained molar masses: M substance / M(K 2 SO 3) = 158 / 158 = 1. So the formula for the compound of potassium, sulfur and oxygen has the form K 2 SO 3. |
| Answer | K2SO3 |
EXAMPLE 2
| Exercise | The composition of the substance includes 32.5% sodium, 22.5% sulfur and 45% oxygen. Bring out chemical formula substances. |
| Solution | The mass fraction of the element X in the molecule of the HX composition is calculated by the following formula: ω (X) = n × Ar (X) / M (HX) × 100%. Let us denote the number of moles of elements that make up the compound as "x" (sodium), "y" (sulfur) and "z" (oxygen). Then, the molar ratio will look like this (the values of relative atomic masses taken from the Periodic Table of D.I. Mendeleev will be rounded to integers): x:y:z = ω(Na)/Ar(Na) : ω(S)/Ar(S) : ω(O)/Ar(O); x:y:z= 32.5/23: 22.5/32: 45/16; x:y:z= 1.4: 0.7: 2.8 = 2: 1: 4. So the formula for the compound of sodium, sulfur and oxygen will look like Na 2 SO 4. It's sodium sulfate. |
| Answer | Na2SO4 |
The chemical structure of H 2 S molecules is similar to the structure of H 2 O molecules: (angular shape)
But, unlike water, H 2 S molecules are of low polarity; hydrogen bonds between them are not formed; the strength of the molecules is much lower.
Physical properties
At normal temperature, H 2 S is a colorless gas with an extremely unpleasant suffocating smell of rotten eggs, very toxic (at a concentration of > 3 g / m 3 causes fatal poisoning). Hydrogen sulfide is heavier than air, easily condenses into a colorless liquid. H 2 S is soluble in water (at normal temperature, 2.5 liters of gas dissolve in 1 liter of H 2 O).
Hydrogen sulfide in nature
H 2 S is present in volcanic and underground gases, in the water of sulfur sources. It is formed during the decay of proteins containing sulfur, and is also released during the vital activity of numerous microorganisms.
How to get
1. Synthesis from simple substances:
S + H 2 \u003d H 2 S
2. Action of non-oxidizing acids on metal sulfides:
FeS + 2HCI \u003d H 2 S + FeCl 2
3. Action conc. H 2 SO 4 (without excess) into alkaline and alkaline earth Me:
5H 2 SO 4 (conc.) + 8Na \u003d H 2 S + 4Na 2 SO 4 + 4H 2 O
4. It is formed during the irreversible hydrolysis of some sulfides:
AI 2 S 3 + 6H 2 O \u003d 3H 2 S + 2Al (OH) 3 ↓
Chemical properties of H 2 S
H 2 S - strong reducing agent
The interaction of H 2 S with oxidizing agents leads to the formation of various substances (S, SO 2, H 2 SO 4),
Reactions with simple oxidizing substances
Air oxygen oxidation
2H 2 S + 3O 2 (excess) \u003d 2SO 2 + 2H 2 O
2H 2 S + O 2 (deficiency) \u003d 2S ↓ + 2H 2 O
Oxidation with halogens:
H 2 S + Br 2 = S↓ + 2НВr
Reactions with oxidizing acids (HNO 3 , H 2 SO 4 (conc.).
3H 2 S + 8HNO 3 (razb.) \u003d 3H 2 SO 4 + 8NO + 4H 2 O
H 2 S + 8HNO 3 (conc.) \u003d H 2 SO 4 + 8NO 2 + 4H 2 O
H 2 S + H 2 SO 4 (conc.) \u003d S ↓ + SO 2 + 2H 2 O
Reactions with salts - oxidizing agents
5H 2 S + 2KMnO 4 + 3H 2 SO 4 = 5S↓ + 2MnSO 4 + K 2 SO 4 + 8H 2 O
5H 2 S + 6KMnO 4 + 9H 2 SO 4 = 5SO 2 + 6MnSO 4 + 3K 2 SO 4 + 14H 2 O
H 2 S + 2FeCl 3 = S↓ + 2FeCl 2 + 2HCl
An aqueous solution of H 2 S exhibits the properties of a weak acid
Hydrosulfide acid H 2 S 2-basic acid dissociates in steps
1st stage: H 2 S → H + + HS -
2nd stage: HS - → H + + S 2-
H 2 S in aqueous solution is characterized by reactions common to a class of acids, in which it behaves like a weak acid. Interacts:
a) with active metals
H 2 S + Mg \u003d H 2 + MgS
b) with low-active metals (Ag, Cu, Hg) in the presence of oxidizing agents
2H 2 S + 4Аg + O 2 = 2Ag 2 S↓ + 2Н 2 O
c) with basic oxides
H 2 S + BaO \u003d BaS + H 2 O
d) with alkalis
H 2 S + NaOH (lack) = NaHS + H 2 O
e) with ammonia
H 2 S + 2NH 3 (excess) = (NH 4) 2 S
Features of the reactions of H 2 S with salts of strong acids
Despite the fact that hydrosulfide acid is very weak, it reacts with some salts of strong acids, for example:
CuSO 4 + H 2 S \u003d CuS ↓ + H 2 SO 4
Reactions proceed in cases where the resulting Me sulfide is insoluble not only in water, but also in strong acids.
Qualitative reaction to the sulfide anion
One of these reactions is used to detect S 2- anions and hydrogen sulfide:
H 2 S + Pb(NO 3) 2 = 2HNO 3 + PbS ↓ black precipitate.
Gaseous H 2 S is detected using wet paper soaked in Pb(NO 3) 2 solution, which turns black in the presence of H 2 S.
Sulfides
Sulfides are binary sulfur compounds with less EO elements, including some non-metals (C, Si, P, As, etc.).
Metal sulfides are of the greatest importance, since many of them are natural compounds and are used as raw materials for the production of free metals, sulfur, and sulfur dioxide.
Reversible hydrolysis of soluble sulfides
Alkaline Me and ammonium sulfides are highly soluble in water, but in aqueous solution they undergo hydrolysis to a very large extent:
S 2- + H 2 O → HS - + OH -
Therefore, sulfide solutions have a strongly alkaline reaction
Alkaline earth sulfides Me and Mg, interacting with water, undergo complete hydrolysis and turn into soluble acid salts - hydrosulfides:
2CaS + 2HOH \u003d Ca (HS) 2 + Ca (OH) 2
When sulfide solutions are heated, hydrolysis also proceeds in the 2nd stage:
HS - + H 2 O → H 2 S + OH -
Irreversible hydrolysis of sulfides
Sulfides of some metals undergo irreversible hydrolysis and completely decompose in aqueous solutions, for example:
Al 2 S 3 + 6H 2 O \u003d 3H 2 S + 2AI (OH) 3 ↓
Cr 2 S 3, Fe 2 S 3 decompose in a similar way
Insoluble sulfides
Most sulfides heavy metals They practically do not dissolve in water and therefore do not undergo hydrolysis. Some of them dissolve under the action of strong acids, for example:
FeS + 2HCI \u003d FeCl 2 + H 2 S
ZnS + 2HCI \u003d ZnCl 2 + H 2 S
Sulfides Ag 2 S, HgS, Hg 2 S, PbS, CuS are insoluble not only in water, but also in many acids.
Oxidative roasting of sulphides
Oxidation of sulfides with atmospheric oxygen at high temperature is an important stage in the processing of sulfide raw materials. Examples:
2ZnS + 3O 2 = 2ZnO + 2SO 2
4FeS 2 + 11O 2 = 2Fe 2 O 3 + 8SO 2
Methods for obtaining sulfides
1. Direct connection of simple substances:
2. Interaction of H 2 S with alkali solutions:
H 2 S + 2NaOH \u003d 2H 2 O + Na 2 S sodium sulfide
H 2 S + NaOH = H 2 O + NaHS sodium hydrosulfide
3. Interaction of H 2 S or (NH 4) 2 S with salt solutions:
H 2 S + CuSO 4 \u003d CuS ↓ + H 2 SO 4
H 2 S + 2AgNO 3 \u003d Ag2S ↓ + 2HNO 3
4. Recovery of sulfates by calcination with coal:
Na 2 SO 4 + 4C \u003d Na 2 S + 4CO
This process is used to produce alkali and alkaline earth metal sulfides.
Hydrogen sulfide - H2S - a colorless gas with a pungent smell of rotten eggs. Poorly soluble in water. Toxic. The hydrogen sulfide molecule has an angular shape. The molecule is polar. Since hydrogen sulfide does not form strong hydrogen bonds, normal conditions hydrogen sulfide is a gas. In an aqueous solution, hydrogen sulfide forms a weak hydrosulfide acid.
Receipt
Displacement by strong acids from salts:
FeS + 2HCl = FeCl2 + H2S (Kipp apparatus)
Hydrogen sulfide reactions: oxidized by atmospheric oxygen to sulfur or sulfur dioxide
2H2S + O2 = 2S(SO2) + 2H2O
Hydrosulfuric acid - weak, dibasic
Hydrosulphuric acid
Insoluble medium salts of hydrosulfide acid (sulfides) are obtained by the interaction of sulfur with metals or in exchange reactions between salt solutions:
Na2S + CuSO4 = CuS↓ + Na2SO4
K2S + FeCl2 = FeS↓ + 2KCl
Soluble sulfides are formed by alkali and alkaline earth metals. They can be obtained by the interaction of acid solutions with metals or alkalis. In this case, depending on the molar ratio between the starting materials, both acidic (hydrosulfides) and medium salts can be formed.
H2S + NaOH = NaHS + H2O (with a lack of alkali)
H2S + 2NaOH = Na2S + 2H2O (in excess alkali)
Some sulfides (CuS, HgS, Ag2S, PbS) are not decomposed by solutions of strong acids. Therefore, hydrosulfide acid can displace strong acids from aqueous solutions of their salts formed by these metals:
CuSO4 + H2S = CuS↓ + H2SO4
HgCl2 + H2S = HgS↓ +2HCl
Hydrosulfuric acid in air is slowly oxidized by oxygen with the release of sulfur:
2H2S + O2 = 2S↓ + 2H2O
Therefore, over time, H2S solutions become cloudy during storage.
Alkaline earth metal sulfides in an aqueous solution are almost 100% hydrolyzed in the first stage and exist in the form of soluble acid salts:
2CaS + 2HOH = Ca(HS)2 + Ca(OH)2
Sulfides of some metals (Al2S3, Fe2S3, Cr2S3) are completely hydrolyzed in H2O:
Al2S3 + 6 H2O = 2Al(OH)3 + 3 H2S
Most heavy metal sulfides are very poorly soluble in H2O.
50) Phosphorus. Allotropic modifications of phosphorus……
Phosphorus is an integral part of plant and animal proteins. In plants, phosphorus is concentrated in the seeds, in animals - in the nervous tissue, muscles, and skeleton. The human body contains about 1.5 kg of phosphorus: 1.4 kg - in the bones,
130 g - in the muscles and 13 g in the nervous tissue. In nature, phosphorus is found in bound form.
The most important minerals:
apatite Ca5(PO4)3F and phosphorite Ca3(PO4)2.
Phosphorus can be obtained by heating a mixture of phosphorite,
coal and sand in a special furnace:
Ca3(PO4)2 + 5C + 3SiO2 2P + 3CaSiO3 + 5CO
Phosphine is a poisonous garlic-smelling gas that can be obtained from zinc phosphide by the action of acids or water:
Zn3P2 + 6HCl → 2PH3 + 3ZnCl2
The main properties of phosphine are weaker than those of ammonia:
PH3 + HCl → PH4Cl
Phosphonium salts in aqueous solutions are unstable:
PH4 + H2O → PH3 + H3O
Phosphine has reducing (the lowest oxidation state of phosphorus), burns in air:
2PH3 + 4O2 → P2O5 + 3H2O
Phosphine is a colorless poisonous gas with the smell of rotten fish. Self-ignites in air
2РН3 + 4О2 → P2O5 + 2Н2О
Slightly soluble in water and, unlike NH3, does not react with it.
With very strong and oxygen-free acids, it forms phosphonium salts similarly to ammonia.
PH3 + HI= PH4I
phosphonium iodide
Diphosphine (analogous to hydrazine) (P2H4) - is a liquid,
self-igniting in air.
Obtaining: From phosphate rock by fusion with carbon and silicon oxide
Ca3(PO4)2 + C +SiO2 → P4 + CaSiO3 + CO
From Ca phosphate, at temperatures above 1500°C: Ca3(PO4)2 + C → CaO + P4 + CO
Chemical properties: P + O2 = P2O3; P + O2 = P2O5; P + S = P2S3; P + Cl2 = PCl3; P + H2 does not go
Allotropic modifications: White phosphorus is a strong poison, even in small doses it is deadly. In the solid state, it is obtained by rapid cooling of phosphorus vapor. In its pure form, it is completely colorless, transparent, appearance similar to wax: brittle in the cold, at temperatures above 15 ° C - soft, easily cut with a knife.
Red phosphorus is a red-brown powder, non-toxic, non-volatile, insoluble in water and in many organic solvents and carbon disulfide; does not ignite in air and does not glow in the dark. It ignites only when heated to 260 °C. With strong heating, without access to air, without melting (bypassing the liquid state), it evaporates - sublimes. When cooled, it turns into white phosphorus.
Black phosphorus is obtained by strong heating and high pressure of white phosphorus. Black phosphorus is heavier than other modifications. It is used very rarely - as a semiconductor in the composition of gallium and indium phosphate in metallurgy.
Reacts with acids P + HNO3 = HPO4 + NO + H2O; P + H2SO4 = H3PO4 + SO2 + H2O
Reacts with alkalis P + KOH + H2O = KH 2PO2 + PH3
An aqueous solution of H 2 S (the formula of hydrogen sulfide acid) is otherwise called hydrogen sulfide water or hydrosulfide acid. This is one of the weakest mineral acids (indicators in it do not change their color), it dissociates in 2 stages:
H 2 S -- H + + HS - K 1 diss. ≈ 6 ∙ 10 -8
HS - -- H + + S 2- K 2 diss. ≈ 1 ∙ 10 -14
Solutions of hydrosulfide acid are dilute, their maximum molar concentration at 20 ° C and atmospheric pressure does not exceed 0.12 mol / l, and the degree of dissociation in the first stage is ~ 0.011%.
Hydrosulphuric acid can react with metals in the range of voltages up to H 2, exhibiting oxidizing properties due to H + ions. But such reactions proceed very slowly under normal conditions due to the low concentration of H + ions in the solution and, mainly, on the surface of the metal, because most salts of hydrosulfide acid are insoluble in H 2 O. Similarly, H 2 S reacts with metal oxides, insoluble hydroxides.
Insoluble Mediums hydrosulphuric acid salts(sulfides) are obtained by the interaction of sulfur with metals or in exchange reactions between salt solutions:
Na 2 S + CuSO 4 \u003d CuS ↓ + Na 2 SO 4
K 2 S + FeCl 2 \u003d FeS ↓ + 2KCl
Soluble sulfides formed by alkali and alkaline earth metals. They can be obtained by the interaction of acid solutions with metals or alkalis. In this case, depending on the molar ratio between the starting materials, both acidic (hydrosulfides) and medium salts can be formed.
H 2 S + NaOH \u003d NaHS + H 2 O (with a lack of alkali)
H 2 S + 2NaOH \u003d Na 2 S + 2H 2 O (in excess alkali)
In aqueous solutions, medium salts are strongly hydrolyzed:
Na 2 S + HOH -- NaHS + NaOH
S 2- + HOH -- HS - + OH -
therefore their solutions have an alkaline reaction.
Alkaline earth metal sulfides in an aqueous solution are almost 100% hydrolyzed in the first stage and exist in the form of soluble acid salts:
2CaS + 2HOH = Ca(HS) 2 + Ca(OH) 2
Sulfides of some metals (Al 2 S 3, Fe 2 S 3, Cr 2 S 3) in H 2 O are completely hydrolyzed:
Al 2 S 3 + 6 H 2 O \u003d 2Al (OH) 3 + 3 H 2 S
Most heavy metal sulfides are very poorly soluble in H2O.
Some sulfides (CuS, HgS, Ag 2 S, PbS) are not decomposed by solutions of strong acids. Therefore, hydrosulfide acid can displace strong acids from aqueous solutions of their salts formed by these metals:
CuSO 4 + H 2 S \u003d CuS ↓ + H 2 SO 4
HgCl 2 + H 2 S \u003d HgS ↓ + 2HCl
Hydrosulfuric acid in air is slowly oxidized by oxygen with the release of sulfur:
2H 2 S + O 2 \u003d 2S ↓ + 2H 2 O
Therefore, over time, H 2 S solutions become cloudy during storage.
Thanks to this reaction, hydrogen sulfide does not accumulate in the upper layers of the Black Sea water, which contain a lot of dissolved oxygen.
Hydrosulfide acid, like hydrogen sulfide, is a strong reducing agent and is oxidized by the same oxidizing agents as H 2 S, with the formation of similar products.
Heavy metal sulfides have various bright colors and are used to obtain mineral paints used in painting.
An important property of sulfides is their oxidation with oxygen during roasting. This reaction is used in metallurgy to obtain non-ferrous metals from sulfide ores:
2CuS + 3O 2 -- 2CuO + 2SO 2
During the firing of active metal sulfides, the resulting SO 2 and metal oxide can react with each other to form salts of sulfurous acid.
PART AND
GENERAL CHEMISTRY
CHEMISTRY OF THE ELEMENTS
OXYGEN. SULFUR
hydrogen sulfide
The hydrogen sulfide molecule consists of a Sulfur atom and two Hydrogen atoms connected by a polar covalent bond. Angle between bonds
SH equals 91°. The hydrogen sulfide molecule is polar.Hydrogen sulfide - natural component volcanic and natural gases. Some mineral waters contain dissolved hydrogen sulfide, which gives them medicinal properties. Hydrogen sulfide is formed as a result of the decay of products containing proteins in their composition. In the Black Sea, at a depth of more than 40 meters, there is no life due to the saturation of the waters with hydrogen sulfide.
Physical properties of hydrogen sulfide
Hydrogen sulfide is a colorless gas with a rotten egg odor. In 1 volume of water, 3 volumes of hydrogen sulfide dissolve, and approximately 0.1 molar solution is formed. The melting point of hydrogen sulfide is -83 °C, and the boiling point is -61 °C. Hydrogen sulfide affects nervous system person, so it is necessary to work with him under a fume hood.
Chemical properties hydrogen sulfide
Hydrogen sulfide is a compound that has a structure similar to the water molecule, but compared to it is less stable. In the case of heating to high temperatures, hydrogen sulfide decomposes according to the reaction:
Combustion can occur in two various directions. In excess of oxygen, water and sulfur are formed (And
V) oxide:Due to the lack of oxygen, incomplete combustion of hydrogen sulfide occurs. This process is used to extract sulfur on an industrial scale from gases that are formed during the roasting of ores:
Bromine and iodine reduce hydrogen sulfide to a simple sulfur substance:
Hydrogen sulfide reacts with hexafluorosulfur at elevated temperatures:
In the case of dissolution of hydrogen sulfide in water, a weak dibasic sulfide acid is formed (K a 1 \u003d 10 - 7, K a 2 \u003d 1.2 ∙ 10 - 13):
Medium salts of sulfide acid are called sulfides (for example, K 2 S is potassium sulfide. Acid salts of the corresponding acid are also known - hydrogen sulfide(KHS - potassium hydrogen sulfide). Since sulfide acid is a rather weak acid, solutions of sulfides and hydrogen sulfides undergo hydrolysis by the anion, and, accordingly, the solution medium is basic:
Alkali and alkaline earth metal sulfides are soluble in water, while other sulfides are insoluble. Many salts of sulfide acid have a characteristic color: HgS - red, Sb 2 S 3 - orange, CdS - yellow, MnS - pink, CuS - black.
Production and use of hydrogen sulfide
Hydrogen sulfide is usually produced by the action of mineral acids on metal sulfides:
Hydrogen sulfide can also be obtained from simple substances.
Hydrogen sulfide is used in the qualitative analysis of cations according to the sulfide classification. He also plays important role during the production of sulfuric acid.
Qualitative reaction to hydrogen sulfide i sulfide ion
To determine sulfide ions in a solution, any soluble lead salt is added to the test solution (most often acetate P b (CH 3 SOO) 2 or nitrate Pb(NO3) 2). If after addition a black precipitate appears in the solution, then sulfide ions were present in the test sample:
If they say that he is weak, then a disease has come, or hunger, in general, adversity. In chemistry, things are different. Consider a weak hydrogen sulfide. It is weak not because it is ready to disintegrate, to perish, but, on the contrary, because of the unwillingness to dissociate.
This is the name given to the process of dissolution in water, separation into a hydronium ion and an anion. Hydrogen sulfide dissociates by only 0.011%, moreover, in two stages. On the first of them, the degree of decomposition does not exceed 0.005%.
So, it is quite resistant, "holds the blow." However, this is by human standards. In chemistry, things are different. Let's dive into its world, continuing to study the properties of hydrogen sulfide.
Properties of hydrosulfide acid
The heroine's resilience is relative. Not wanting to completely dissolve in water, the compound decomposes under the action of oxygen. It oxidizes hydrosulfide acid. Formula it looks like this: - H 2 S. H in it -, S -. So, the latter, during oxidation, “breaks out” of the formula. The connection breaks up.
In fact, hydrosulfide acid is aqueous solution gas. Hydrogen sulfide is known for its rotten egg smell and toxicity. the substance does not. There are no indicator papers that have been in hydrosulphuric acid. Property this is another pointer to the weakness of the connection. Strong color litmus in tones.
Characteristics of hydrosulfide acid is reduced not only to slow dissolution in water. Other reactions with the heroine of the article also pass slowly. In relation to the human character, this is rather laziness than weakness.
With metals, for example, a hydrogen sulfide solution reacts reluctantly. 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 that are up to H 2 in the voltage series. Such elements are capable of displacing hydrogen from solution. The interaction can lead to the formation hydrosulphuric acid salts.
It is completely insoluble in water. The response concerns sulfides. This is one of the types formed with the participation of a hydrogen sulfide compound. The second type is hydrosulfides. They are formed during the reaction with alkali and alkaline earth, soluble.
Entering into interaction with alkaline earth metals, hydrogen sulfide reacts with alkalis. The heroine of the article acts as a reducer, that is, she gives away electrons. It turns out that the properties of the connection are typical for a weak type.
The other 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. Where and how it is used, we will tell in the next chapter.
The use of hydrosulfide acid
Dissociation of hydrosulfide acid to a solution of saturation in thousandths of a percent allows the use of the compound for medicinal purposes. They, as a rule, are organized at the places where groundwater containing hydrogen sulfide comes out. 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, more quickly supplies the organs with the elements they need. The metabolism is accelerated, leading to the purification of toxins. On the general effect of rejuvenation.
"On the face" used in direct 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 notice that hydrogen sulfide baths are not taken at home and, in general, indoors. The concentration of vapors emanating from the water may exceed the permissible values.
In sanatoriums, they try to place pools in the open air. Hot springs. Therefore, swimming in them is pleasant even in winter. There are a number of hydrogen sulfide resorts, for example, near the city of Severobaikalsk.
Doctors supervising the guests recommend the heroine of the article also as a cure for ailments of the genitourinary system. True, pregnant and lactating procedures are contraindicated. But, for those who want to become a parent, hydrogen sulfide baths will not hurt.
In the west of the country, hydrogen sulfide is formed along the Black Sea shelf. True, there the compound is formed at a depth of about 150 meters, emerging as bubbles in shallow water.
If temporary procedures in a gas atmosphere are acceptable, then prolonged inhalation of hydrogen sulfide leads to the extinction of the ability to smell. This is the result of paralysis of the olfactory nerve.
How to recognize hydrosulphuric acid in the air at a low concentration, in the absence of an obvious smell? Will only help. She is also poisonous, but otherwise nothing. Wet in the reagent. In an atmosphere with a hydrogen sulfide content of at least 0.0000001%, the sheet will be covered with bloom.
Obtaining hydrosulfide acid
Since it is a solution of hydrogen sulfide, it is worth wondering how to obtain it. A popular way to use and sulfide. As the latter, natural minerals are taken. There are several sulfides in the bowels of the planet. The most famous, perhaps. Its formula: - FeS 2 .
The reaction between sulfide and violent, with active evolution of gas. Accordingly, the interaction is carried out in isolated rooms, using protective clothing and clothing.
Industrialists often go the other way. Hydrogen sulfide is a by-product of many industries. It remains only 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 prices.
Hydrosulphuric acid price
Since in everyday life the heroine of the article is needed only for water procedures, the form of selling the compound is reduced to for hydrogen sulfide baths. Example: - Means "Matsesta". It is sold in pharmacies, like other drugs of the group.
"Matsesta" is sold in packages, added to a bath with 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.
Nobody canceled the remark about the danger of taking hydrogen sulfide baths at home. But, manufacturers are reinsured, choosing the optimal, safe concentration. With her, do not apply for 15 minutes.
For laboratory needs and industrial production, it makes no sense to pay for water with a minimum 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 for gas cylinders, as a rule, it is negotiable.
SECTION II. INORGANIC CHEMISTRY
9.3. ElementsVIAgroups
9.3.7. Hydrogen sulfide (hydrogen sulfide). Hydrogen sulfide (sulfide) acid. Sulphides 2
Hydrogen sulfide and hydrosulfide acid Hydrogen sulfide or hydrogen sulfide H 2 S , is a volatile compound of Sulfur with Hydrogen. In a hydrogen sulfide molecule, the sulfur atom forms two covalent polar bonds with two hydrogen atoms. The bond angle is 92.1°. Solution H 2 S in water is called hydrosulphuric acid.
The prevalence of hydrogen sulfide in nature
In nature, hydrogen sulfide is found in the composition of natural and volcanic gases, is found in the water of some mineral springs, and is also formed during the decomposition of organic substances (plant and animal residues), and therefore is found in small amounts in the air.
Huge reserves of hydrogen sulfide accumulated in the depths of the Black Sea: its layer starts from a depth of 150-200 m and reaches the bottom (maximum depth - 2210 m). The concentration of hydrogen sulfide at a depth of 150 m - 0.19 mg/l sea water, at a depth of 200 m - 0.83 mg / l, and at a depth of 2000 m it reaches 9.60 mg / l. Thus, with the exception of some specific micro-organisms, there are almost no living beings.
Physical properties and physiological action of hydrogen sulfide
Hydrogen sulfide - a colorless gas with a sharp unpleasant smell of rotten eggs - water dissolves up to 2.5 liters of H 2 S. Hydrogen sulfide is very toxic. The presence in the air of a volume fraction of 0.1% causes poisoning. Hydrogen sulfide binds hemoglobin, forming with an ion Fe2+ , which is part of it, a small-sized compound - ferrum (II) sulfide.
Extraction of hydrogen sulfide
In the laboratory, to extract hydrogen sulfide, a reaction is used between the sulfide of a metal element and perchloric acid or dilute sulfuric acid:
In industry, hydrogen sulfide is produced by passing hydrogen over molten sulfur:
Chemical properties of hydrogen sulfide and sulfide acid
hydrogen sulfide
1. Hydrogen sulfide burns with a bluish flame:
With a lack of oxygen, sulfur is formed:
2. Hydrogen sulfide is classified as a strong reducing agent - it can be oxidized to sulfur, sulfur (I V ) oxide or sulfuric acid:
3. Hydrogen sulfide interacts with oxidizing acids:
4. Reacts with both strong and weak oxidants:
The use of hydrogen sulfide
1. In the chemical industry for the production of sulfuric acid, elemental sulfur, sulfides.
2. In the organic synthesis of sulfur-containing substances (thiols 3).
3. As a reagent in analytical chemistry for the detection of ions of heavy metal elements (Ag + , Pb 2+ , С u 2+).
4. In the future, it is possible to use the giant reserves of hydrogen sulfide contained in the Black Sea for the needs of hydrogen sulfide energy and the chemical industry.
5. In medicine natural springs and artificial baths containing hydrogen sulfide are used to combat skin diseases.
Sulfonic acid
A solution of hydrogen sulfide in water is hydrogen sulfide water, or hydrogen sulfide (sulfide) acid is a weak dibasic acid. It is weaker than sulfite acid H 2 SO 3 . It dissociates in two stages (after the II degree - to a small extent):
Sulfonic acid exhibits general properties acids. It reacts with basic oxides, bases, forming medium and acidic salts, as well as with some salts and metals:
Salts of hydrosulphuric acid
Hydrosulfuric acid forms two series of salts: medium - sulfides (K 2 S, CaS) - and acidic - hydrogen sulfide(KHS, Ca(HS ) 2). Water-soluble sulfides of alkali and alkaline earth metal elements, as well as ammonium sulfide(NH4)2S. Some sulfides have a characteristic color: black - PbS and CuS, yellow - CdS, white - ZnS, MgS, pink - MnS.
Chemical properties of sulfides
1. Water-soluble sulfides slowly hydrolyze, that is, they are decomposed by water:
As a result of complete hydrolysis in solution, some sulfides cannot be obtained:
2. Sulfides react with some other salts:
These two reactions are qualitative for the detection of the sulfide ion S 2- , because the formation of characteristic black precipitates is observed - CuS and PbS.
3. Sulfides are decomposed by strong acids:
4. Sulfides, when interacting with oxidizing agents, exhibit reducing properties:
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1 The reaction is used to bind spilled mercury (demercurization). The floor area where the mercury thermometer has broken should be sprinkled with sulfur powder. Cinnabar is a non-poisonous compound. It does not evaporate (at room temperature) and can be easily collected.
2 Polysulfides - Sulfur compounds with the general formula X 2 S n , whose structure contains chains of atoms - S-S(n-2)-S - where, depending on the component X, n may vary: in hydrogen polysulfides H2Sn (oily liquid depending on the sulfur content from yellow to red) n varies from 2 to 23, in ammonium polysulfides ( NH 4) 2 S n - 2 to 9, alkali metals Me 2 S n - from 2 to 8. They are used in the leather industry to remove hair from the skin), in the production of dyes, polysulfide rubbers, in analytical chemistry.
3 Thiols (or mercaptans) have a strong unpleasant odor. In particular, egantiol C2H5SH added to natural gas (methane is odorless) before it enters the domestic gas pipeline to detect gas leaks from the system.
