Pulmonary hydrogen sulfide acid. The formula of hydrogen sulfide acid. Oxidative fir sulphids

Definition

Hydrogen sulfide It is a colorless gas with a characteristic smell of rotting protein.

It is a little heavier than air, is liquefied at a temperature of -60.3 o C and hardens at -85.6 o C. The air hydrogen sulfide burns with a blue flame, forming sulfur dioxide and water:

2H 2 S + 3O 2 \u003d 2H 2 O + 2SO 2.

If you make a cold object into the sulfide flame, such a cold object, such as a porcelain cup, then the temperature of the flame is significantly reduced and hydrogen sulfide is oxidized only to free sulfur, sedenting on a cup as a yellow plaque:

2H 2 S + O 2 \u003d 2H 2 O + 2S.

Hydrogen sulfide is easily flammable; The mixture of it with air bleaks. Hydrogen sulfide is very poisonous. Long sighation of air containing this gas even in small quantities causes severe poisoning.

At 20 o with one volume of water dissolves 2.5 sulfide volume. The solution of hydrogen sulfide in water is called hydrogen sulfide water. When standing in the air, especially in light, hydrogen sulfide water becomes muddy from the highlighting sulfur. This occurs as a result of oxidation of hydrogen sulfide with air oxygen.

Obtaining sulfide

For high temperatures Sulfur interacts with hydrogen, forming gas hydrogen sulfide.

Practically hydrogen sulfide is usually obtained by the action of diluted acids on sulfur metal, for example, iron sulphide:

FES + 2HCl \u003d FECL 2 + H 2 S.

Pushful hydrogen sulfide can be obtained by hydrolysis CAS, BAS or A1 2 S 3. The purest gas is a direct reaction of hydrogen and sulfur at 600 ° C.

Chemical properties of sulfurodor

The hydrogen sulfide solution in water has acid properties. Hydrogen sulfide - weak dibasic acid. It dissociates stepped and mainly at the first stage:

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 negligible.

Hydrogen sulfide is a strong reducing agent. Under the action of strong oxidants, 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 oxidant. For example, the reaction with chlorine usually proceeds to sulfuric acid formation:

H 2 S + 4Cl 2 + 4H 2 O \u003d H 2 SO 4 + 8HCl.

The middle salts of hydrogen sulfide are called sulfides.

Application of sulfide

The use of hydrogen sulfide is rather limited, which is primarily associated with its high toxicity. He found applied in laboratory practice as a precipitator heavy metals. Hydrogen sulfide serves as raw material for obtaining sulfuric acid, sulfur in elementary form and sulfides

Examples of solving problems

Example 1.

The task	Determine how many times heavier air hydrogen sulfide H 2 S.
Decision	The ratio of the mass of this gas to the mass of the other gas, taken in the same volume, at the same temperature and the same pressure, is called the relative density of the first gas on the second. This value shows how many times the first gas is heavier or lighter than the second gas. The relative molecular weight of the 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 consumed conditionally, as the air is a mixture of gases. D AIR (H 2 S) \u003d M R (H 2 S) / M R (AIR); D AIR (H 2 S) \u003d 34/29 \u003d 1.17. M R (H 2 S) \u003d 2 × A R (H) + A R (S) \u003d 2 × 1 + 32 \u003d 2 + 32 \u003d 34.
Answer	Hydrogen sulfide H 2 S is heavier than air 1.17 times.

Example 2.

The task	Find the hydrogen density of the mixture of gases in which the volume fraction of oxygen is 20%, hydrogen - 40%, the rest is hydrogen sulfide H 2 S.
Decision	Volumetric shares of gases will coincide with molar, i.e. With the shares of the amount of substances, this is a consequence of the Avogadro law. Find a conditional molecular weight of the mixture: M R Conditional (Mixture) \u003d φ (O 2) × M R (O 2) + φ (H 2) × M R (H 2) + φ (H 2 S) × M R (H 2 S);

Definition

Hydrogen sulfide acid (hydrogen sulfide, monosulfan) under normal conditions is a colorless gas.

Thermally unstable. Few soluble B. cold water. A saturated solution (0.1 m) is called "hydrogen sulfide water", which is muttered when standing in the air. Shows weak acid properties. The OSR is a strong reducing agent.

Chemical hydrogen sulfide formula

Chemical formula hydrogen sulfide acid H 2 S. It shows that the composition of this molecule includes two hydrogen atoms (Ar \u003d 1 AE.m.) and one sulfur atom (Ar \u003d 32 A.M.). By chemical formula, it is possible to calculate the molecular weight of hydrogen sulfide acid:

Mr (H 2 S) \u003d 2 × AR (H) + Ar (S);

Mr (H 2 S) \u003d 2 × 1 + 32 \u003d 2 +32 \u003d 34.

Graphic (structural) hydrogen sulfide formula

The structural (graphic) formula of hydrogen sulfide is more visual. It shows how the atoms between themselves are connected inside the molecule (Fig. 1).

Fig. 1. The structure of the hydrogen sulfide molecule with an indication of the valence angle between the bonds and the length of chemical bonds.

Ion formula

Hydrogen sulfide acid is an electrolyte, i.e. In an aqueous solution, it is able to dissociate by ions according to the following equation:

H 2 S ↔ 2H + + S 2-.

Examples of solving problems

Example 1.

The task	Determine the molecular formula of 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.
Decision	Denote the amount of mole of elements included in the compound for "x" (potassium), "y" (sulfur) and "z" (oxygen). Then, the molar ratio will look as follows (the values \u200b\u200bof the relative atomic masses taken from Periodic table DI. Mendeleev, rounded to integers): x: y: z \u003d ω (k) / ar (k): ω (s) / ar (s): ω (o) / ar (o); x: y: z \u003d 49.4 / 39: 20,2 / 32: 30.4 / 16; x: y: z \u003d 1,3: 0.63: 1,9 \u003d 2: 1: 3. So simplest formula Connections of potassium, sulfur and oxygen will be viewed K 2 SO 3 and molar Mass 158 g / mol. We 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 a true formula organic compound Find the ratio of the resulting molar masses: M substance / m (k 2 SO 3) \u003d 158/158 \u003d 1. Therefore, the formula for the compound of potassium, sulfur and oxygen has the form K 2 SO 3.
Answer	K 2 SO 3

Example 2.

The task	The substance includes 32.5% sodium, 22.5% sulfur and 45% oxygen. Output chemical formula Substances.
Decision	The mass fraction of the element x in the molecule of the composition HX is calculated according to the following formula: ω (x) \u003d n × ar (x) / m (HX) × 100%. Denote the amount of mole elements included in the compound for "x" (sodium), "y" (sulfur) and "z" (oxygen). Then, the molar ratio will look as follows (the values \u200b\u200bof the relative atomic masses taken from the periodic table D.I. Mendeleev, rounded to integers): x: y: z \u003d ω (na) / ar (na): ω (s) / ar (s): ω (o) / ar (o); x: y: z \u003d 32.5/23: 22,5 / 32: 45/16; x: Y: Z \u003d 1,4: 0.7: 2.8 \u003d 2: 1: 4. Therefore, the formula for the compound of sodium, sulfur and oxygen will be viewed Na 2 SO 4. This sodium sulfate.
Answer	Na 2 SO 4

Physical properties

Gas, colorless, with a smell of rotten eggs, poisonous, soluble in water (in 1V h 2 o dissolves 3 V H 2 S with N.U.); T ° PL. \u003d -86 ° C; T ° KIP. \u003d -60 ° C.

Effect of hydrogen sulfide on the body:

The hydrogen sulfide will not only smell badly, it is also extremely poisonous. When inhalation of this gas in large quantities, paralysis of respiratory nerves is coming, and then the person ceases to feel the smell - this is the deadly danger of hydrogen sulfide.

There are many cases of poisoning of harmful gas when the workers were injured, on the repair of pipelines. This gas is heavier, so it accumulates in the pits, wells, from where it is not so easy to get away.

Obtaining

1) H 2 + S → H 2 S (at T)

2) FES + 2 HCl → FECL 2 + H 2 S

Chemical properties

1) Solution H. 2 S. In water - weak dibasic acid.

Dissociation occurs in two steps:

H 2 S → H + + HS - (the first step is formed hydrosulfide - ion)

HS - → 2 H + + S 2- (Second step)

Hydrogenic acid forms two rows of salts - medium (sulfides) and acidic (hydrosulfides):

Na. 2 S. - sodium sulphide;

Cas. - calcium sulphide;

NaHS. - sodium hydrosulfide;

CA.( HS.) 2 - calcium hydrosulfide.

2) interacts with the grounds:

H 2 S + 2 NaOH (excess) → Na 2 S + 2 H 2 O

H 2 S (excess) + NaOH → Na n S + H 2 O

3) H. 2 S. Shows very strong reducing properties:

H 2 S -2 + BR 2 → S 0 + 2HBR

H 2 S -2 + 2FeCl 3 → 2FeCl 2 + S 0 + 2HCl

H 2 S -2 + 4Cl 2 + 4H 2 O → H 2 S +6 O 4 + 8HCl

3H 2 S -2 + 8HNO 3 (concluding) → 3H 2 S +6 O 4 + 8NO + 4H 2 O

H 2 S -2 + H 2 S +6 O 4 (concluding) → S 0 + S +4 O 2 + 2H 2 O

(When heated, the reaction is in different:

H 2 S -2 + 3H 2 S +6 O 4 (CON) → 4S +4 O 2 + 4H 2 O

4) hydrogen sulfide oxidizes:

with lack O. 2

2 H 2 S -2 + O 2 → 2 S 0 + 2 H 2 O

with an excess O 2

2H 2 S -2 + 3O 2 → 2S +4 O 2 + 2H 2 O

5) Silver in contact with hydrogen sulfide black:

4 AG + 2 H 2 S + O 2 → 2 AG 2 S ↓ + 2 H 2 O

Dammonious objects can be brilliantly. To do this, in enameled dishes they are boiled with a solution of soda and aluminum foil. Aluminum restores silver to metal, and soda solution holds sulfur ions.

6) Quality reaction on hydrogen sulfide and soluble sulphides - education of dark brown (almost black) sediment PBS.:

H 2 S + PB (NO 3) 2 → PBS ↓ + 2HNO 3

Na 2 S + Pb (NO 3) 2 → PBS ↓ + 2Nano 3

PB 2+ + S 2- → PBS ↓

The contamination of the atmosphere causes the surface of the surface of paintings written by oil paints, which includes lead whites. One of the main reasons for the darkening of art paintings of the old masters was the use of lead Belil, which for several centuries, interacting with traces of hydrogen sulfide in the air (formed in small quantities in the rotation of proteins; in the atmosphere of industrial regions, etc.) turn into PBS.. Leading Belil is a pigment that is a lead carbonate ( II.). It reacts with a hydrogen sulfide contained in a contaminated atmosphere, forming lead sulfide ( II.), black compound:

PBCO. 3 + H. 2 S. = PBS.↓ + Co. 2 + H. 2 O.

When processing sulfide lead ( II.) The hydrogen peroxide reacts:

PBS. + 4 H. 2 O. 2 = PBSO. 4 + 4 H. 2 O.,

at the same time, lead sulphate is formed ( II.), White connection.

Thus restore the blackened oil paintings.

7) Restoration:

PBS + 4 H 2 O 2 → PBSO 4 (white) + 4 H 2 O

Sulfida

Obtaining sulphides.

1) Many sulphides are obtained by heating the metal with gray:

HG + S → HGS

2) soluble sulphides are obtained by the action of hydrogen sulfide for alkali:

H 2 S + 2 KOH → K 2 S + 2 H 2 O

3) insoluble sulphides are obtained by exchange reactions:

CDCl 2 + Na 2 S → 2NACL + CDS ↓

PB (NO 3) 2 + Na 2 S → 2Nano 3 + PBS ↓

ZNSO 4 + Na 2 S → Na 2 SO 4 + ZNS ↓

MNSO 4 + Na 2 S → Na 2 SO 4 + MNS ↓

2SBCl 3 + 3NA 2 S → 6NACL + SB 2 S 3 ↓

SNCl 2 + Na 2 S → 2NACL + SNS ↓

Chemical properties sulfides

1) soluble sulphides are strongly hydrolyzed, as a result of which their aqueous solutions have an alkaline reaction:

K 2 S + H 2 O → KHS + KOH

S 2- + H 2 O → HS - + OH -

2) Metal sulfides in a series of voltages to the left of iron (inclusive) soluble in strong acids:

ZNS + H 2 SO 4 → ZNSO 4 + H 2 S

3) insoluble sulphides can be transferred to the soluble state of the action of concentrated Hno. 3 :

FES 2 + 8HNO 3 → Fe (NO 3) 3 + 2H 2 SO 4 + 5NO + 2H 2 O

Tasks for fixing

Task number 1
Write the reaction equations with which the following transformations can be carried out:
Cu.→ CUS.→ H 2 S.→ SO 2.

Task number 2.
Make the equations of redox reactions of complete and incomplete combustion of hydrogen sulfide. Put the coefficients by the method of electronic balance, specify the oxidizing agent and the reducing agent for each reaction, as well as the processes of oxidation and recovery.

Task number 3.
Write down the equation chemical reaction hydrogen sulfide with lead nitrate solution (II) in molecular, full and short ion form. Note the signs of this reaction if the reaction is reversible?

Task number 4.

The hydrogen sulfide was passed through a 18% solution of copper (II) sulfate (II) weighing 200 g. Calculate the mass of the precipitate, which dropped as a result of this reaction.

Task number 5.
Determine the volume of hydrogen sulfide (N.U.) formed by the interaction of hydrochloric acid with a 25% solution of iron sulfide (II) weighing 2 kg?

An aqueous solution H 2 S (formula of sulfuric acid) is called otherwise hydrogen sulfide water or hydrogen sulfide acid. This is one of the weakest mineral acids (indicators in it do not change their painting), 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

Hydrogen sulfide acid solutions are diluted, their maximum molar concentration at 20 o C and atmospheric pressure does not exceed 0.12 mol / l, and the degree of dissociation at the first stage at the same time is ~ 0.011%.

Hydrogen sulfide acid can react with metals in a row of stresses up to H 2, showing oxidative properties due to H + ions. But such reactions under normal conditions occur very slowly due to the low concentration of H + ions in solution and, mainly on the metal surface, because Most hydrogen sulfuric acid salts are insoluble in H 2 O. Similarly, H 2 S reacts with metal oxides, insoluble hydroxides.

Insoluble averages hydrogen sulfide salts (sulphides) are obtained by the interaction of sulfur with metals or in the exchange reactions between salts solutions:

Na 2 S + Cuso 4 \u003d CUS ↓ + Na 2 SO 4

K 2 S + FECL 2 \u003d FES ↓ + 2KCL

Soluble sulfida Formed alkaline and alkaline earth metals. They can be obtained by interaction of acid solutions with metals or alkalis. At the same time, depending on the molar ratio between the starting materials, both acidic (hydrosulfides) and the average salts can be formed.

H 2 S + NaOH \u003d NaHS + H 2 O (with a shortage of alkali)

H 2 S + 2NAOH \u003d Na 2 S + 2H 2 O (in an excess of 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.

Sulfida alkaline earth metals In an aqueous solution, in the first stage, almost 100% is hydrolyzed and exist as soluble acidic salts:

2CAS + 2HOH \u003d Ca (HS) 2 + CA (OH) 2

Sulphides of some metals (Al 2 S 3, Fe 2 S 3, Cr 2 S 3) in H 2 O are hydrolyzed completely:

Al 2 S 3 + 6 H 2 O \u003d 2AL (OH) 3 + 3 H 2 S

Most heavy metal sulphides are very poorly soluble in H 2 O.

Some sulphides (CUS, HGS, AG 2 S, PBS) are not decomposed by solutions of strong acids. Therefore, hydrogen sulfide acid can displace strong acids of aqueous solutions 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

Hydrogen sulfide acid in air slowly oxidized with sulfur separation:

2H 2 S + O 2 \u003d 2S ↓ + 2H 2 O

Therefore, with time, the solutions of H 2 S during storage are muttered.

Due to this reaction, hydrogen sulfide is not accumulated in the upper layers of the water of the Black Sea, which contain a lot of dissolved oxygen.

Hydrogen sulfide acid, as well as hydrogen sulfide, is a strong reducing agent and oxidized by the same oxidizing agents as H 2 S, with the formation of similar products.

Heavy metals sulfides have a different bright color and are used to produce mineral paints used in painting.

An important property of sulfides is their oxygen oxidation during firing. This reaction is used in metallurgy to obtain non-ferrous metals from sulphide ores:

2CUS + 3O 2 - 2CUO + 2SO 2

In the firing of the sulfides of active metals, the formed SO 2 and metal oxide can react with each other with the formation of sulfur salts.