Sulfuric acid. Properties, extraction, application and price of sulfuric acid

OVR in the article is specially highlighted in color. Pay special attention to them. These equations can get caught in the exam.

Dilute sulfuric acid behaves like other acids, hiding its oxidative capabilities:

And one more thing to remember about dilute sulfuric acid: she is does not react with lead. A piece of lead thrown into dilute H2SO4 is covered with a layer of insoluble (see solubility table) lead sulfate and the reaction stops immediately.

Oxidizing properties of sulfuric acid

- heavy oily liquid, non-volatile, tasteless and odorless

Due to sulfur in the +6 (higher) oxidation state, sulfuric acid acquires strong oxidizing properties.

Rule for task 24 (old A24) when preparing sulfuric acid solutions never pour water into it. Concentrated sulfuric acid should be poured into water in a thin stream, stirring constantly.

The interaction of concentrated sulfuric acid with metals

These reactions are strictly standardized and follow the scheme:

H2SO4(conc.) + metal → metal sulfate + H2O + reduced sulfur product.

There are two nuances:

1) aluminum, iron and chromium do not react with H2SO4 (conc) under normal conditions due to passivation. Need to heat up.

2) C platinum and gold H2SO4 (conc) does not react at all.

Sulfur in concentrated sulfuric acid- oxidizing agent

• it means that she will recover herself;
• the degree of oxidation to which sulfur will be reduced depends on the metal.

Consider sulfur oxidation state diagram:

• Before -2 sulfur can be reduced only by very active metals - in a series of voltages up to and including aluminum.

The reactions will go like this:

8Li + 5H 2 SO 4( conc .) → 4Li 2 SO 4 + 4H 2 O+H 2 S

4Mg + 5H 2 SO 4( conc .) → 4MgSO 4 + 4H 2 O+H 2 S

8Al + 15H 2 SO 4( conc .) (t) → 4Al 2 (SO 4 ) 3 + 12H 2 O+3H 2 S

• in the interaction of H2SO4 (conc) with metals in a series of voltages after aluminum but before iron, that is, with metals with an average activity, sulfur is reduced to 0 :

3Mn+4H 2 SO 4( conc .) → 3MnSO 4 + 4H 2 O+S↓

2Cr+4H 2 SO 4( conc .) (t) → Cr 2 (SO 4 ) 3 + 4H 2 O+S↓

3Zn + 4H 2 SO 4( conc .) → 3ZnSO 4 + 4H 2 O+S↓

• all other metals starting with iron in a series of voltages (including those after hydrogen, except for gold and platinum, of course), they can only reduce sulfur up to +4. Since these are inactive metals:

2 Fe + 6 H 2 SO 4(conc.) ( t)→ Fe 2 ( SO 4 ) 3 + 6 H 2 O + 3 SO 2

(note that iron oxidizes to +3, the highest possible, highest oxidation state, as it deals with a strong oxidizing agent)

Cu+2H 2 SO 4( conc .) → CuSO 4 + 2H 2 O+SO 2

2Ag + 2H 2 SO 4( conc .) → Ag 2 SO 4 + 2H 2 O+SO 2

Of course, everything is relative. The depth of reduction will depend on many factors: acid concentration (90%, 80%, 60%), temperature, etc. Therefore, it is impossible to accurately predict the products. The table above also has its own percentage of approximation, but you can use it. It is also necessary to remember that in the Unified State Examination, when the product of reduced sulfur is not indicated, and the metal is not particularly active, then, most likely, the compilers mean SO 2. You need to look at the situation and look for clues in the conditions.

SO 2 - this is generally a frequent product of OVR with the participation of conc. sulfuric acid.

H2SO4 (conc) oxidizes some nonmetals(which exhibit reducing properties), as a rule, to the maximum - the highest degree of oxidation (an oxide of this non-metal is formed). Sulfur is also reduced to SO 2:

C+2H 2 SO 4( conc .) → CO 2 + 2H 2 O+2SO 2

2P+5H 2 SO 4( conc .) → P 2 O 5 + 5H 2 O+5SO 2

Freshly formed phosphorus oxide (V) reacts with water, orthophosphoric acid is obtained. Therefore, the reaction is recorded immediately:

2P+5H 2 SO 4( conc ) → 2H 3 PO 4 + 2H 2 O+5SO 2

The same with boron, it turns into orthoboric acid:

2B+3H 2 SO 4( conc ) → 2H 3 BO 3 + 3SO 2

Very interesting is the interaction of sulfur with an oxidation state of +6 (in sulfuric acid) with "another" sulfur (located in another compound). Within the framework of the exam, the interaction of H2SO4 (conc) is considered with sulfur (a simple substance) and hydrogen sulfide.

Let's start with interaction sulfur (a simple substance) with concentrated sulfuric acid. In a simple substance, the oxidation state is 0, in an acid +6. In this OVR, sulfur +6 will oxidize sulfur 0. Let's look at the diagram of sulfur oxidation states:

Sulfur 0 will be oxidized, and sulfur +6 will be reduced, that is, lower the oxidation state. Sulfur dioxide will be emitted:

2 H 2 SO 4(conc.) + S → 3 SO 2 + 2 H 2 O

But in the case of hydrogen sulfide:

Both sulfur (a simple substance) and sulfur dioxide are formed:

H 2 SO 4( conc .) + H 2 S → S↓ + SO 2 + 2H 2 O

This principle can often help in determining an OVR product where the oxidizing agent and reducing agent are the same element, in different oxidation states. The oxidizing agent and reducing agent "go towards each other" on the oxidation state diagram.

H2SO4 (conc), one way or another, interacts with halides. Only here you need to understand that fluorine and chlorine are “themselves with a mustache” and OVR does not leak with fluorides and chlorides, undergoes the usual ion-exchange process, during which gaseous hydrogen halide is formed:

CaCl 2 + H 2 SO 4 (conc.) → CaSO 4 + 2HCl

CaF 2 + H 2 SO 4(conc.) → CaSO 4 + 2HF

But the halogens in the composition of bromides and iodides (as well as in the composition of the corresponding hydrogen halides) are oxidized by it to free halogens. Only now sulfur is reduced in different ways: iodide is a stronger reducing agent than bromide. Therefore, iodide reduces sulfur to hydrogen sulfide, and bromide to sulfur dioxide:

2H 2 SO 4( conc .) + 2NaBr → Na 2 SO 4 + 2H 2 O+SO 2 +Br 2

H 2 SO 4( conc .) + 2HBr → 2H 2 O+SO 2 +Br 2

5H 2 SO 4( conc .) + 8NaI → 4Na 2 SO 4 + 4H 2 O+H 2 S+4I 2 ↓

H 2 SO 4( conc .) + 8HI → 4H 2 O+H 2 S+4I 2 ↓

Hydrogen chloride and hydrogen fluoride (as well as their salts) are resistant to the oxidizing action of H2SO4 (conc).

And finally, the last thing: for concentrated sulfuric acid, this is unique, no one else can do it. She possesses water-removing property.

This allows you to use concentrated sulfuric acid in a variety of ways:

First, the dehydration of substances. Concentrated sulfuric acid takes water away from the substance and it "becomes dry".

Secondly, a catalyst in reactions in which water is split off (for example, dehydration and esterification):

H 3 C–COOH + HO–CH 3 (H 2 SO 4 (conc.)) → H 3 C–C(O)–O–CH 3 + H 2 O

H 3 C–CH 2 –OH (H 2 SO 4 (conc.)) → H 2 C \u003d CH 2 + H 2 O

H2SO4, lat. Acidum sulfuricum is a strong dibasic acid with a molar mass of about 98 g/mol.

Pure sulfuric acid is a colorless, odorless, caustic oily liquid with a density of 1.84 g/cm3, which turns into a solid crystalline mass at 10.4°C. The boiling point of aqueous solutions of sulfuric acid increases with an increase in its concentration and reaches a maximum at a content of about 98% H2SO4.

Concentrated sulfuric acid reacts very violently with water, as a large amount of heat is released (19 kcal per mole of acid) due to the formation of hydrates. For this reason, sulfuric acid should always be diluted by pouring it into water, and not vice versa.

Sulfuric acid is highly hygroscopic, that is, it absorbs water vapor from the air well, so it can be used to dry gases that do not react with it. Hygroscopicity also explains the charring of organic substances, for example, sugar or wood, when exposed to concentrated sulfuric acid. In this case, hydrates of sulfuric acid are formed. Also, due to its low volatility, it is used to displace other, more volatile acids from their salts.

Concentrated sulfuric acid is a strong oxidizing agent. It oxidizes metals in the voltage series up to and including silver, and the reaction products depend on the conditions of its implementation and the activity of the metal itself. It forms two series of salts: medium - sulfates and acidic - hydrosulfates, as well as ethers.

Dilute sulfuric acid interacts with all metals that are in the electrochemical series of voltages to the left of hydrogen (H), with the release of H2, oxidizing properties are not typical for it.

In industry, sulfuric acid is produced by two methods: the contact method using solid catalysts (contacts), and the nitrous method with nitrogen oxides. The raw materials are sulfur, metal sulfides, etc. Several grades of acid are produced, depending on the purity and concentration: battery (the purest), technical, tower, vitriol, oleum (solution of sulfuric anhydride in sulfuric acid).

Application of sulfuric acid:

• The production of mineral fertilizers is the largest area of ​​application
• electrolyte in lead batteries
• Manufacture of synthetic detergents, dyes, plastics, hydrogen fluoride and other reagents
• Enrichment of ores in the mining industry
• Refining of oil products
• Metalworking, textile, leather and other industries
• Production of medicines
• Registered in the food industry as a food additive E513
• Industrial organic synthesis

The use of sulfuric acid in industry

The food industry is familiar with sulfuric acid in the form of food additive E513. The acid acts as an emulsifier. This food additive is used in the manufacture of beverages. It helps regulate acidity. In addition to food, E513 is part of mineral fertilizers. The use of sulfuric acid in industry is widespread. Industrial organic synthesis uses sulfuric acid to carry out the following reactions: alkylation, dehydration, hydration. With the help of this acid, the required amount of resins on filters is restored, which are used in the production of distilled water.

The use of sulfuric acid in everyday life

Sulfuric acid at home is in demand among motorists. The process of preparing an electrolyte solution for a car battery is accompanied by the addition of sulfuric acid. When working with this acid, you should remember the safety rules. If acid gets on clothing or exposed skin, rinse immediately with running water. Sulfuric acid that has spilled onto metal can be neutralized with lime or chalk. When refueling a car battery, it is necessary to follow a certain sequence: gradually add acid to water, and not vice versa. When water reacts with sulfuric acid, the liquid becomes very hot, which can cause it to splatter. Therefore, you should be especially careful not to get the liquid on your face or eyes. Acid must be stored in a tightly closed container. It is important that the chemical is kept out of the reach of children.

The use of sulfuric acid in medicine

Sulfuric acid salts are widely used in medicine. For example, magnesium sulfate is prescribed to people in order to achieve a laxative effect. Another derivative of sulfuric acid is sodium thiosulfate. The drug is used as an antidote in case of administration of the following substances: mercury, lead, halogens, cyanide. Sodium thiosulfate, together with hydrochloric acid, is used to treat dermatological diseases. Professor Demyanovich proposed the union of these two drugs for the treatment of scabies. In the form of an aqueous solution, sodium thiosulfate is administered to people who suffer from allergic ailments.

Magnesium sulfate has a wide range of possibilities. Therefore, it is used by doctors of various specialties. As an antispasmodic, magnesium sulfate is administered to patients with hypertension. If a person has diseases of the gallbladder, the substance is administered orally to improve bile secretion. The use of sulfuric acid in medicine in the form of magnesium sulfate in gynecological practice is common. Gynecologists help women in labor by administering magnesium sulfate intramuscularly, in this way they anesthetize childbirth. In addition to all the above properties, magnesium sulfate has an anticonvulsant effect.

The use of sulfuric acid in production

Sulfuric acid, the fields of application of which are diverse, is also used in the production of mineral fertilizers. For more convenient cooperation, factories that produce sulfuric acid and mineral fertilizers are mainly located close to each other. This moment creates continuous production.

The use of sulfuric acid in the manufacture of dyes and synthetic fibers is the second most common after the production of mineral fertilizers. Many industries use sulfuric acid in some manufacturing processes. The use of sulfuric acid has found demand in everyday life. People use the chemical to service their cars. You can buy sulfuric acid in stores that specialize in the sale of chemicals, including our link. Sulfuric acid is transported in accordance with the rules for the transport of such cargo. Rail or road transport transports acid in appropriate containers. In the first case, a tank acts as a container, in the second - a barrel or container.

Application features and biohazard

Sulfuric acid and products close to it are extremely toxic substances that have been assigned hazard class II. Their vapors affect the respiratory tract, skin, mucous membranes, cause difficulty in breathing, cough, often - laryngitis, tracheitis, bronchitis. The maximum permissible concentration of sulfuric acid vapors in the air of the working area of ​​industrial premises is 1 mg/m3. People working with toxic acids are provided with overalls and personal protective equipment. Concentrated sulfuric acid, if handled carelessly, can cause chemical burns.

If sulfuric acid is ingested, immediately after ingestion, sharp pains appear in the mouth and the entire digestive tract, severe vomiting mixed first with scarlet blood, and then with brown masses. Simultaneously with vomiting, a strong cough begins. A sharp swelling of the larynx and vocal cords develops, causing severe breathing difficulties. The pupils dilate, and the skin of the face takes on a dark blue color. There is a fall and weakening of cardiac activity. Death occurs at a dose of 5 milligrams. In case of sulfuric acid poisoning, urgent gastric lavage and magnesium intake are necessary.

Sulfuric acid, H2SO4, a strong dibasic acid corresponding to the highest oxidation state of sulfur (+6). Under normal conditions - a heavy oily liquid, colorless and odorless. In engineering, sulfuric acid is called its mixtures with both water and sulfuric anhydride. If the molar ratio of SO3: H2O is less than 1, then this is an aqueous solution of sulfuric acid, if more than 1, it is a solution of SO3 in sulfuric acid.

Natural deposits of native sulfur are relatively small. The total sulfur content in the earth's crust is 0.1%. Sulfur is found in oil, coal, combustible and flue gases. Sulfur is most often found in nature in the form of compounds with zinc, copper and other metals. It should be noted that the share of pyrites and sulfur in the total balance of sulfuric acid raw materials is gradually decreasing, and the share of sulfur extracted from various wastes is gradually increasing. The possibilities for obtaining sulfuric acid from waste are very significant. The use of waste gases from non-ferrous metallurgy makes it possible to obtain, without special costs, in sulfuric acid systems for the roasting of sulfur-containing raw materials.

Physical and chemical properties of sulfuric acid

100% H2SO4 (SO3 x H2O) is called monohydrate. The compound does not smoke, in a concentrated form it does not destroy ferrous metals, while being one of the strongest acids;

• the substance has a detrimental effect on plant and animal tissues, taking away water from them, as a result of which they are charred.
• crystallizes at 10.45 "C;
• tkip 296.2 "C;
• density 1.9203 g/cm3;
• heat capacity 1.62 J/g.

Sulfuric acid mixes with H2O and SO3 in any ratio, forming compounds:

• H2SO4 x 4 H2O (tmelt - 28.36 "C),
• H2SO4 x 3 H2O (tmelt - 36.31 "C),
• H2SO4 x 2 H2O (tmelt - 39.60 "C),
• H2SO4 x H2O (tmelt - 8.48 "C),
• H2SO4 x SO3 (H2S2O7 - disulfuric or pyrosulfuric acid, mp 35.15 "C) - oleum,
• H2SO x 2 SO3 (H2S3O10 - trisulfuric acid, mp 1.20 "C).

When aqueous solutions of sulfuric acid containing up to 70% H2SO4 are heated and boiled, only water vapor is released into the vapor phase. Sulfuric acid vapors also appear above more concentrated solutions. A solution of 98.3% H2SO4 (azeotropic mixture) is completely distilled at boiling (336.5 "C). Sulfuric acid containing more than 98.3% H2SO4 releases SO3 vapor when heated.
Concentrated sulfuric acid is a strong oxidizing agent. It oxidizes HI and HBr to free halogens. When heated, it oxidizes all metals except Au and platinum metals (with the exception of Pd). In the cold, concentrated sulfuric acid passivates many metals, including Pb, Cr, Ni, steel, cast iron. Dilute sulfuric acid reacts with all metals (except Pb) that precede hydrogen in the voltage series, for example: Zn + H2SO4 = ZnSO4 + H2.

How the strong acid H2SO4 displaces weaker acids from their salts, such as boric acid from borax:

Na2B4O7 + H2SO4 + 5 H2O = Na2SO4 + 4 H2BO3,

and when heated, it displaces more volatile acids, for example:

NaNO3 + H2SO4 = NaHSO4 + HNO3.

Sulfuric acid takes away chemically bound water from organic compounds containing hydroxyl groups - OH. Dehydration of ethyl alcohol in the presence of concentrated sulfuric acid leads to the production of ethylene or diethyl ether. Charring of sugar, cellulose, starch and other carbohydrates upon contact with sulfuric acid is also explained by their dehydration. As a dibasic, sulfuric acid forms two types of salts: sulfates and hydrosulfates.

Raw materials for the production of sulfuric acid

The raw materials for the production of sulfuric acid can be: sulfur, sulfur pyrite FeS2, exhaust gases from oxidative roasting of sulfide ores Zn, Cu, Pb and other metals containing SO2. In Russia, the main amount of sulfuric acid is obtained from sulfur pyrites. FeS2 is burned in furnaces where it is in a fluidized bed state. This is achieved by rapidly blowing air through a layer of finely ground pyrites. The resulting gas mixture contains SO2, O2, N2, impurities of SO3, vapors of H2O, As2O3, SiO2 and others, and carries a lot of cinder dust, from which gases are cleaned in electrostatic precipitators.

Methods for producing sulfuric acid

Sulfuric acid is obtained from SO2 in two ways: nitrous (tower) and contact.

nitrous method

The processing of SO2 into sulfuric acid by the nitrous method is carried out in production towers - cylindrical tanks (15 m or more high) filled with a packing of ceramic rings. From above, towards the gas flow, "nitrose" is sprayed - dilute sulfuric acid containing nitrosyl sulfuric acid NOOSO3H, obtained by the reaction:

N2O3 + 2 H2SO4 = 2 NOOSO3H + H2O.

Oxidation of SO2 by nitrogen oxides occurs in solution after its absorption by nitrose. Nitrose is hydrolyzed by water:

NOOSO3H + H2O = H2SO4 + HNO2.

Sulfur dioxide entering the towers forms sulfurous acid with water:

SO2 + H2O = H2SO3.

The interaction of HNO2 and H2SO3 leads to the production of sulfuric acid:

2 HNO2 + H2SO3 = H2SO4 + 2 NO + H2O.

The liberated NO is converted in the oxidation tower into N2O3 (more precisely, into a mixture of NO + NO2). From there, the gases enter the absorption towers, where sulfuric acid is supplied to meet them from above. Nitrose is formed, which is pumped into the production towers. Thus, the continuity of production and the cycle of nitrogen oxides are ensured. Their inevitable losses with exhaust gases are replenished by the addition of HNO3.

Sulfuric acid obtained by the nitrous method has an insufficiently high concentration and contains harmful impurities (for example, As). Its production is accompanied by the release of nitrogen oxides into the atmosphere ("fox tail", so named for the color of NO2).

contact way

The principle of the contact method for the production of sulfuric acid was discovered in 1831 by P. Philips (Great Britain). The first catalyst was platinum. At the end of the 19th - beginning of the 20th centuries. acceleration of the oxidation of SO2 to SO3 by vanadium anhydride V2O5 was discovered. The studies of the Soviet scientists A. E. Adadurov, G. K. Boreskov, and F. N. Yushkevich played a particularly important role in the study of the action of vanadium catalysts and their selection.

Modern sulfuric acid plants are built to work according to the contact method. Vanadium oxides with additions of SiO2, Al2O3, K2O, CaO, BaO in various proportions are used as the basis of the catalyst. All vanadium contact masses show their activity only at a temperature not lower than ~ 420 ° C. In the contact apparatus, the gas usually passes 4 or 5 layers of the contact mass. In the production of sulfuric acid by the contact method, the roasting gas is preliminarily purified from impurities that poison the catalyst. dust residues are removed in washing towers irrigated with sulfuric acid.Fog is removed from sulfuric acid (formed from SO3 and H2O present in the gas mixture) in wet electrostatic precipitators.H2O vapor is absorbed by concentrated sulfuric acid in drying towers.The SO2-air mixture then passes through the catalyst ( contact mass) and oxidized to SO3:

SO2 + 1/2 O2 = SO3.

SO3 + H2O = H2SO4.

Depending on the amount of water entering the process, a solution of sulfuric acid in water or oleum is obtained.
About 80% of the world's H2SO4 is now produced by this method.

The use of sulfuric acid

Sulfuric acid can be used to purify petroleum products from sulfurous, unsaturated organic compounds.

In metallurgy, sulfuric acid is used to remove scale from wire, as well as sheets before tinning and galvanizing (diluted), for pickling various metal surfaces before coating them with chromium, copper, nickel, etc. Complex ores are also decomposed with sulfuric acid (in particular, uranium).

In organic synthesis, concentrated sulfuric acid is a necessary component of nitrating mixtures, as well as a sulphurizing agent in the production of many dyes and medicinal substances.

Sulfuric acid is widely used for the production of fertilizers, ethyl alcohol, artificial fibers, caprolactam, titanium dioxide, aniline dyes and a number of other chemical compounds.

Spent sulfuric acid (waste) is used in chemical, metallurgical, woodworking and other industries. Battery sulfuric acid is used in the production of lead-acid current sources.

DEFINITION

anhydrous sulfuric acid is a heavy, viscous liquid that is easily miscible with water in any proportion: the interaction is characterized by an exceptionally large exothermic effect (~880 kJ / mol at infinite dilution) and can lead to explosive boiling and splashing of the mixture if water is added to the acid; that is why it is so important to always use the reverse order in the preparation of solutions and add the acid to the water, slowly and with stirring.

Some physical properties of sulfuric acid are given in the table.

Anhydrous H 2 SO 4 is a remarkable compound with an unusually high dielectric constant and very high electrical conductivity, which is due to the ionic autodissociation (autoprotolysis) of the compound, as well as the proton transfer relay conduction mechanism, which ensures the flow of electric current through a viscous liquid with a large number of hydrogen bonds.

Table 1. Physical properties of sulfuric acid.

Getting sulfuric acid

Sulfuric acid is the most important industrial chemical and the cheapest bulk acid produced anywhere in the world.

Concentrated sulfuric acid ("vitriol oil") was first obtained by heating "green vitriol" FeSO 4 ×nH 2 O and spent in large quantities to obtain Na 2 SO 4 and NaCl.

The modern process for producing sulfuric acid uses a catalyst consisting of vanadium(V) oxide with the addition of potassium sulfate on a carrier of silicon dioxide or diatomaceous earth. Sulfur dioxide SO 2 is obtained by burning pure sulfur or by roasting sulfide ore (primarily pyrite or ores of Cu, Ni and Zn) in the process of extracting these metals. Then SO 2 is oxidized to trioxide, and then sulfuric acid is obtained by dissolving in water:

S + O 2 → SO 2 (ΔH 0 - 297 kJ / mol);

SO 2 + ½ O 2 → SO 3 (ΔH 0 - 9.8 kJ / mol);

SO 3 + H 2 O → H 2 SO 4 (ΔH 0 - 130 kJ / mol).

Chemical properties of sulfuric acid

Sulfuric acid is a strong dibasic acid. In the first stage, in solutions of low concentration, it dissociates almost completely:

H 2 SO 4 ↔H + + HSO 4 -.

Dissociation on the second stage

HSO 4 - ↔H + + SO 4 2-

proceeds to a lesser extent. The dissociation constant of sulfuric acid in the second stage, expressed in terms of ion activity, K 2 = 10 -2.

As a dibasic acid, sulfuric acid forms two series of salts: medium and acidic. Medium salts of sulfuric acid are called sulfates, and acid salts are called hydrosulfates.

Sulfuric acid greedily absorbs water vapor and is therefore often used to dry gases. The ability to absorb water also explains the charring of many organic substances, especially those belonging to the class of carbohydrates (fiber, sugar, etc.), when exposed to concentrated sulfuric acid. Sulfuric acid removes hydrogen and oxygen from carbohydrates, which form water, and carbon is released in the form of coal.

Concentrated sulfuric acid, especially hot, is a vigorous oxidizing agent. It oxidizes HI and HBr (but not HCl) to free halogens, coal to CO 2 , sulfur to SO 2 . These reactions are expressed by the equations:

8HI + H 2 SO 4 \u003d 4I 2 + H 2 S + 4H 2 O;

2HBr + H 2 SO 4 \u003d Br 2 + SO 2 + 2H 2 O;

C + 2H 2 SO 4 \u003d CO 2 + 2SO 2 + 2H 2 O;

S + 2H 2 SO 4 \u003d 3SO 2 + 2H 2 O.

The interaction of sulfuric acid with metals proceeds differently depending on its concentration. Dilute sulfuric acid oxidizes with its hydrogen ion. Therefore, it interacts only with those metals that are in the series of voltages only up to hydrogen, for example:

Zn + H 2 SO 4 \u003d ZnSO 4 + H 2.

However, lead does not dissolve in dilute acid because the resulting PbSO 4 salt is insoluble.

Concentrated sulfuric acid is an oxidizing agent due to sulfur (VI). It oxidizes metals in the voltage series up to and including silver. The products of its reduction can be different depending on the activity of the metal and on the conditions (acid concentration, temperature). When interacting with low-active metals, such as copper, the acid is reduced to SO 2:

Cu + 2H 2 SO 4 \u003d CuSO 4 + SO 2 + 2H 2 O.

When interacting with more active metals, reduction products can be both dioxide and free sulfur and hydrogen sulfide. For example, when interacting with zinc, reactions can occur:

Zn + 2H 2 SO 4 \u003d ZnSO 4 + SO 2 + 2H 2 O;

3Zn + 4H 2 SO 4 = 3ZnSO 4 + S↓ + 4H 2 O;

4Zn + 5H 2 SO 4 \u003d 4ZnSO 4 + H 2 S + 4H 2 O.

The use of sulfuric acid

The use of sulfuric acid varies from country to country and from decade to decade. So, for example, in the USA, the main area of ​​H 2 SO 4 consumption is fertilizer production (70%), followed by chemical production, metallurgy, oil refining (~5% in each area). In the UK, the distribution of consumption by industry is different: only 30% of H 2 SO 4 produced is used in the production of fertilizers, but 18% goes to paints, pigments and dye intermediates, 16% to chemical production, 12% to soap and detergents, 10 % for the production of natural and artificial fibers and 2.5% is used in metallurgy.

Examples of problem solving

EXAMPLE 1

Sulfuric acid finds the widest application in the national economy and is the main product of the basic chemical industry. In this regard, there is a continuous increase in the production of sulfuric acid. So, if in 1900 the world production of sulfuric acid amounted to 4.2 million g, then in 1937 it was received 18.8 million g, and in 1960 - more than 47 million tons.
At present, the Soviet Union ranks second in the world in the production of sulfuric acid. In 1960, the USSR produced 5.4 million g of sulfuric acid. In 1965, the production of sulfuric acid compared to 1958 will be doubled.
The areas of application of sulfuric acid are due to its properties and low cost. Sulfuric acid is a strong, hardly volatile and stable acid, which at moderate temperatures has very weak oxidizing and strong water-removing properties.

The main consumer of sulfuric acid is the production of mineral fertilizers - superphosphate and ammonium sulfate. For example, the production of only one ton of superphosphate (from fluorapatite), which does not contain hygroscopic water, consumes 600 kg of 65% sulfuric acid. The production of mineral fertilizers consumes about half of all acid produced.
A significant amount of sulfuric acid is consumed in the processing of liquid fuels - for the purification of kerosene, paraffin, lubricating oils from sulfur and unsaturated compounds, in the processing of coal tar. It is also used in the purification of various mineral oils and fats.
Sulfuric acid is widely used in various organic syntheses, for example, for the sulfonation of organic compounds in the production of sulfonic acids, various dyes, and saccharin. For this purpose, both concentrated acid and fuming acid, as well as chlorosulfonic acid, are used. Sulfuric acid is used as a water-removing agent in nitration reactions - in the production of nitrobenzene, nitrocellulose, nitroglycerin, etc.
Being a non-volatile acid, sulfuric acid is able to displace volatile acids from their salts, which is used in the production of hydrogen fluoride and hydrogen chloride, perchloric acid.
Sulfuric acid is often used in the processing (decomposition) of certain ores and concentrates, such as titanium, zirconium, vanadium, and sometimes niobium, lithium, and some other metals. Since concentrated sulfuric acid boils at a fairly high temperature and has practically no effect on cast iron and steel, this decomposition can be carried out quite completely using cheap equipment made from these materials.
Dilute hot sulfuric acid dissolves metal oxides well, and it is used for the so-called etching of metals - cleaning them< особенно железа, от окислов.
Sulfuric acid is a good drying agent and is widely used in laboratories and industry for this purpose. Residual humidity when using 95% sulfuric acid is equal to 0.003 mg of water vapor per 1 liter of dried gas.