Any acid is a complex substance, the molecule of which contains one or more hydrogen atoms and an acid residue.
The formula of sulfuric acid is H2SO4. Therefore, the composition of the sulfuric acid molecule includes two hydrogen atoms and the acid residue SO4.
Sulfuric acid is formed when sulfur oxide reacts with water
SO3+H2O -> H2SO4
Pure 100% sulfuric acid (monohydrate) is a heavy liquid, viscous like oil, colorless and odorless, with a sour "copper" taste. Already at a temperature of +10 ° C, it solidifies and turns into a crystalline mass.
Concentrated sulfuric acid contains approximately 95% H2SO4. And it freezes at temperatures below -20 ° C.
Interaction with water
Sulfuric acid is highly soluble in water, mixing with it in any ratio. This releases a large amount of heat.
Sulfuric acid is able to absorb water vapor from the air. This property is used in industry for drying gases. Gases are dried by passing them through special containers with sulfuric acid. Of course, this method can only be used for those gases that do not react with it.
It is known that when sulfuric acid comes into contact with many organic substances, especially carbohydrates, these substances are charred. The fact is that carbohydrates, like water, contain both hydrogen and oxygen. Sulfuric acid robs them of these elements. What remains is coal.
In an aqueous solution of H2SO4, the indicators litmus and methyl orange turn red, which indicates that this solution has a sour taste.
Interaction with metals
Like any other acid, sulfuric acid is capable of replacing hydrogen atoms with metal atoms in its molecule. It interacts with almost all metals.
dilute sulfuric acid reacts with metals like a normal acid. As a result of the reaction, a salt with an acidic residue SO4 and hydrogen are formed.
Zn + H2SO4 = ZnSO4 + H2
BUT concentrated sulfuric acid is a very strong oxidizing agent. It oxidizes all metals, regardless of their position in the voltage series. And when reacting with metals, it itself is reduced to SO2. Hydrogen is not released.
Сu + 2 H2SO4 (conc) = CuSO4 + SO2 + 2H2O
Zn + 2 H2SO4 (conc) = ZnSO4 + SO2 + 2H2O
But gold, iron, aluminum, platinum group metals do not oxidize in sulfuric acid. Therefore, sulfuric acid is transported in steel tanks.
Sulfuric acid salts, which are obtained as a result of such reactions, are called sulfates. They are colorless and crystallize easily. Some of them are highly soluble in water. Only CaSO4 and PbSO4 are sparingly soluble. BaSO4 is almost insoluble in water.
Interaction with bases
The reaction of an acid with a base is called a neutralization reaction. As a result of the neutralization reaction of sulfuric acid, a salt containing the acid residue SO4 and water H2O is formed.
Examples of sulfuric acid neutralization reactions:
H2SO4 + 2 NaOH = Na2SO4 + 2 H2O
H2SO4 + CaOH = CaSO4 + 2 H2O
Sulfuric acid enters into a neutralization reaction with both soluble and insoluble bases.
Since there are two hydrogen atoms in the sulfuric acid molecule, and two bases are required to neutralize it, it belongs to dibasic acids.
Interaction with basic oxides
From the school chemistry course, we know that oxides are called complex substances, which include two chemical elements, one of which is oxygen in the oxidation state -2. Basic oxides are called oxides of 1, 2 and some 3 valence metals. Examples of basic oxides: Li2O, Na2O, CuO, Ag2O, MgO, CaO, FeO, NiO.
With basic oxides, sulfuric acid enters into a neutralization reaction. As a result of such a reaction, as in the reaction with bases, salt and water are formed. The salt contains the acid residue SO4.
CuO + H2SO4 = CuSO4 + H2O
Salt interaction
Sulfuric acid reacts with salts of weaker or volatile acids, displacing these acids from them. As a result of this reaction, a salt with an acidic residue SO4 and an acid
H2SO4+BaCl2=BaSO4+2HCl
The use of sulfuric acid and its compounds
Barium porridge BaSO4 is able to delay x-rays. Filling it with the hollow organs of the human body, radiologists examine them.
In medicine and construction, natural gypsum CaSO4 * 2H2O, calcium sulfate hydrate is widely used. Glauber's salt Na2SO4 * 10H2O is used in medicine and veterinary medicine, in the chemical industry - for the production of soda and glass. Copper sulfate CuSO4 * 5H2O is known to gardeners and agronomists who use it to control pests and plant diseases.
Sulfuric acid is widely used in various industries: chemical, metalworking, petroleum, textile, leather and others.
Undiluted sulfuric acid is a covalent compound.
In a molecule, sulfuric acid is tetrahedrally surrounded by four oxygen atoms, two of which are part of the hydroxyl groups. The S–O bonds are double, and the S–OH bonds are single.
Colorless, ice-like crystals have a layered structure: each H 2 SO 4 molecule is connected to four adjacent strong hydrogen bonds, forming a single spatial framework.
The structure of liquid sulfuric acid is similar to the structure of solid one, only the integrity of the spatial frame is broken.
Physical properties of sulfuric acid
Under normal conditions, sulfuric acid is 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 SO 3: H 2 O is less than 1, then this is an aqueous solution of sulfuric acid, if more than 1, it is a solution of SO 3 in sulfuric acid.
100% H 2 SO 4 crystallizes at 10.45 °C; T bp = 296.2 °C; density 1.98 g/cm 3 . H 2 SO 4 mixes with H 2 O and SO 3 in any ratio to form hydrates, the heat of hydration is so high that the mixture can boil, splatter and cause burns. Therefore, it is necessary to add acid to water, and not vice versa, since when water is added to acid, lighter water will be on the surface of the acid, where all the heat released will be concentrated.
When aqueous solutions of sulfuric acid containing up to 70% H 2 SO 4 are heated and boiled, only water vapor is released into the vapor phase. Sulfuric acid vapors also appear above more concentrated solutions.
In terms of structural features and anomalies, liquid sulfuric acid is similar to water. Here is the same system of hydrogen bonds, almost the same spatial framework.
Chemical properties of sulfuric acid
Sulfuric acid is one of the strongest mineral acids; due to its high polarity, the H-O bond is easily broken.
Sulfuric acid dissociates in aqueous solution , forming a hydrogen ion and an acid residue:
H 2 SO 4 \u003d H + + HSO 4 -;
HSO 4 - \u003d H + + SO 4 2-.
Summary Equation:
H 2 SO 4 \u003d 2H + + SO 4 2-.
Shows the properties of acids , reacts with metals, metal oxides, bases and salts.
Dilute sulfuric acid does not exhibit oxidizing properties; when it interacts with metals, hydrogen and a salt containing the metal in the lowest oxidation state are released. In the cold, acid is inert to metals such as iron, aluminum, and even barium.
The concentrated acid has oxidizing properties. Possible products of interaction of simple substances with concentrated sulfuric acid are given in the table. The dependence of the reduction product on the concentration of the acid and the degree of activity of the metal is shown: the more active the metal, the deeper it reduces the sulfate ion of sulfuric acid.
Interaction with oxides:
CaO + H 2 SO 4 \u003d CaSO 4 \u003d H 2 O.
Interaction with bases:
2NaOH + H 2 SO 4 \u003d Na 2 SO 4 + 2H 2 O.
Interaction with salts:
Na 2 CO 3 + H 2 SO 4 = Na 2 SO 4 + CO 2 + H 2 O.
Oxidizing properties
Sulfuric acid oxidizes HI and HBr to free halogens:
H 2 SO 4 + 2HI \u003d I 2 + 2H 2 O + SO 2.
Sulfuric acid removes chemically bound water from organic compounds containing hydroxyl groups. Dehydration of ethyl alcohol in the presence of concentrated sulfuric acid leads to the production of ethylene:
C 2 H 5 OH \u003d C 2 H 4 + H 2 O.
Charring of sugar, cellulose, starch and other carbohydrates upon contact with sulfuric acid is also explained by their dehydration:
C 6 H 12 O 6 + 12H 2 SO 4 \u003d 18H 2 O + 12SO 2 + 6CO 2.
Structural formula
True, empirical, or gross formula: H2SO4
Chemical composition of sulfuric acid
Molecular weight: 98.076
Sulfuric acid H 2 SO 4 is a strong dibasic acid, corresponding to the highest oxidation state of sulfur (+6). Under normal conditions, concentrated sulfuric acid is a heavy oily liquid, colorless and odorless, with a sour "coppery" taste. In technology, sulfuric acid is called its mixtures with both water and sulfuric anhydride SO 3. If the molar ratio of SO 3: H 2 O is less than 1, then this is an aqueous solution of sulfuric acid, if more than 1 - a solution of SO 3 in sulfuric acid (oleum).
Name
In the XVIII-XIX centuries, sulfur for gunpowder was produced from sulfur pyrites (pyrite) at vitriol plants. Sulfuric acid at that time was called "vitriol oil" (as a rule it was a crystalline hydrate, resembling oil in consistency), hence the origin of the name of its salts (or rather crystalline hydrates) - vitriol.
Getting sulfuric acid
Industrial (contact) method
In industry, sulfuric acid is produced by the oxidation of sulfur dioxide (sulphurous gas produced during the combustion of sulfur or pyrites) to trioxide (sulfuric anhydride), followed by the interaction of SO 3 with water. The sulfuric acid obtained by this method is also called contact (concentration 92-94%).
Nitrous (tower) method
Previously, sulfuric acid was obtained exclusively by the nitrous method in special towers, and the acid was called tower acid (75% concentration). The essence of this method is the oxidation of sulfur dioxide with nitrogen dioxide in the presence of water.
Another way
In those rare cases when hydrogen sulfide (H 2 S) displaces sulfate (SO 4 -) from salt (with metals Cu, Ag, Pb, Hg), sulfuric acid is a by-product. Sulfides of these metals have the highest strength, as well as a distinctive black color.
Physical and physico-chemical properties
A very strong acid, at 18 o C pK a (1) \u003d -2.8, pK a (2) \u003d 1.92 (K z 1.2 10 -2); bond lengths in the molecule S=O 0.143 nm, S-OH 0.154 nm, angle HOSOH 104°, OSO 119°; boils, forming an azeotropic mixture (98.3% H 2 SO 4 and 1.7% H 2 O with a boiling point of 338.8 ° C). Sulfuric acid, corresponding to 100% H 2 SO 4 content, has a composition (%): H 2 SO 4 99.5, HSO 4 - - 0.18, H 3 SO 4 + - 0.14, H 3 O + - 0.09, H 2 S 2 O 7 , - 0.04, HS 2 O 7 - - 0.05. Miscible with water and SO 3 in all proportions. In aqueous solutions, sulfuric acid almost completely dissociates into H 3 O + , HSO 3 + , and 2HSO 4 - . Forms hydrates H 2 SO 4 nH 2 O, where n = 1, 2, 3, 4 and 6.5.
Oleum
Solutions of sulfuric anhydride SO 3 in sulfuric acid are called oleum, they form two compounds H 2 SO 4 SO 3 and H 2 SO 4 2SO 3. Oleum also contains pyrosulfuric acids. The boiling point of aqueous solutions of sulfuric acid increases with its concentration and reaches a maximum at a content of 98.3% H 2 SO 4 . The boiling point of oleum decreases with increasing SO 3 content. With an increase in the concentration of aqueous solutions of sulfuric acid, the total vapor pressure over the solutions decreases and, at a content of 98.3% H 2 SO 4, reaches a minimum. With an increase in the concentration of SO 3 in oleum, the total vapor pressure above it increases. The vapor pressure over aqueous solutions of sulfuric acid and oleum can be calculated by the equation:
log p=A-B/T+2.126
the values of the coefficients A and B depend on the concentration of sulfuric acid. Steam over aqueous solutions of sulfuric acid consists of a mixture of water vapor, H 2 SO 4 and SO 3, while the composition of the vapor differs from the composition of the liquid at all concentrations of sulfuric acid, except for the corresponding azeotropic mixture. As the temperature rises, dissociation increases. The oleum H 2 SO 4 ·SO 3 has the maximum viscosity; with increasing temperature, η decreases. The electrical resistance of sulfuric acid is minimal at a concentration of SO 3 and 92% H 2 SO 4 and maximum at a concentration of 84 and 99.8% H 2 SO 4 . For oleum, the minimum ρ is at a concentration of 10% SO 3 . As the temperature rises, the ρ of sulfuric acid increases. Dielectric constant of 100% sulfuric acid 101 (298.15 K), 122 (281.15 K); cryoscopic constant 6.12, ebulioscopic constant 5.33; the diffusion coefficient of sulfuric acid vapor in air varies with temperature; D = 1.67 10⁻⁵T3/2 cm²/s.
Chemical properties
Sulfuric acid in concentrated form when heated is a fairly strong oxidizing agent. Oxidizes HI and partially HBr to free halogens. Oxidizes many metals (exceptions: Au, Pt, Ir, Rh, Ta.). In this case, concentrated sulfuric acid is reduced to SO 2 . In the cold in concentrated sulfuric acid, Fe, Al, Cr, Co, Ni, Ba are passivated and the reactions do not proceed. With the strongest reducing agents, concentrated sulfuric acid is reduced to S and H 2 S. Concentrated sulfuric acid absorbs water vapor, so it is used to dry gases, liquids and solids, for example, in desiccators. However, concentrated H 2 SO 4 is partially reduced by hydrogen, which is why it cannot be used for drying it. Splitting water from organic compounds and leaving black carbon (coal) at the same time, concentrated sulfuric acid leads to charring of wood, sugar and other substances. Diluted H 2 SO 4 interacts with all metals that are in the electrochemical series of voltages to the left of hydrogen with its release. Oxidizing properties for dilute H 2 SO 4 are uncharacteristic. Sulfuric acid forms two series of salts: medium - sulfates and acidic - hydrosulfates, as well as esters. Peroxomonosulfuric (or Caro's acid) H 2 SO 5 and peroxodisulfuric H 2 S 2 O 8 acids are known. Sulfuric acid also reacts with basic oxides to form sulfate and water. In metalworking plants, a sulfuric acid solution is used to remove a layer of metal oxide from the surface of metal products that are subjected to strong heating during the manufacturing process. So, iron oxide is removed from the surface of sheet iron by the action of a heated solution of sulfuric acid. A qualitative reaction to sulfuric acid and its soluble salts is their interaction with soluble barium salts, in which a white precipitate of barium sulfate is formed, insoluble in water and acids, for example.
Application
Sulfuric acid is used:
- in the processing of ores, especially in the extraction of rare elements, including uranium, iridium, zirconium, osmium, etc.;
- in the production of mineral fertilizers;
- as an electrolyte in lead batteries;
- to obtain various mineral acids and salts;
- in the production of chemical fibers, dyes, smoke-forming and explosive substances;
- in the oil, metalworking, textile, leather and other industries;
- in the food industry - registered as a food additive E513 (emulsifier);
- in industrial organic synthesis in reactions:
- dehydration (obtaining diethyl ether, esters);
- hydration (ethanol from ethylene);
- sulfonation (synthetic detergents and intermediates in the production of dyes);
- alkylation (obtaining isooctane, polyethylene glycol, caprolactam), etc.
- For the recovery of resins in filters in the production of distilled water.
World production of sulfuric acid approx. 160 million tons per year. The largest consumer of sulfuric acid is the production of mineral fertilizers. For P 2 O 5 phosphate fertilizers, 2.2-3.4 times more sulfuric acid is consumed by mass, and for (NH 4) 2 SO 4 sulfuric acid 75% of the mass of consumed (NH 4) 2 SO 4. Therefore, sulfuric acid plants tend to be built in conjunction with plants for the production of mineral fertilizers.
Historical information
Sulfuric acid has been known since antiquity, occurring in nature in a free form, for example, in the form of lakes near volcanoes. Perhaps the first mention of acid gases obtained by calcining alum or iron sulfate "green stone" is found in writings attributed to the Arab alchemist Jabir ibn Hayyan. In the 9th century, the Persian alchemist Ar-Razi, calcining a mixture of iron and copper sulfate (FeSO 4 7H 2 O and CuSO 4 5H 2 O), also obtained a solution of sulfuric acid. This method was perfected by the European alchemist Albert Magnus, who lived in the 13th century. Scheme for the production of sulfuric acid from ferrous sulfate - thermal decomposition of iron (II) sulfate, followed by cooling the mixture. The writings of the alchemist Valentine (XIII century) describe a method for producing sulfuric acid by absorbing gas (sulphuric anhydride) released by burning a mixture of sulfur and saltpeter powders with water. Subsequently, this method formed the basis of the so-called. "chamber" method, carried out in small chambers lined with lead, which does not dissolve in sulfuric acid. In the USSR, such a method existed until 1955. Alchemists of the 15th century also knew a method for obtaining sulfuric acid from pyrite - sulfur pyrite, a cheaper and more common raw material than sulfur. Sulfuric acid was produced in this way for 300 years, in small quantities in glass retorts. Subsequently, due to the development of catalysis, this method replaced the chamber method for the synthesis of sulfuric acid. Currently, sulfuric acid is produced by catalytic oxidation (on V 2 O 5) of sulfur oxide (IV) to sulfur oxide (VI), and subsequent dissolution of sulfur oxide (VI) in 70% sulfuric acid to form oleum. In Russia, the production of sulfuric acid was first organized in 1805 near Moscow in the Zvenigorod district. In 1913, Russia ranked 13th in the world in the production of sulfuric acid.
additional information
The smallest droplets of sulfuric acid can form in the middle and upper atmosphere as a result of the reaction of water vapor and volcanic ash containing large amounts of sulfur. The resulting suspension, due to the high albedo of sulfuric acid clouds, makes it difficult for sunlight to reach the surface of the planet. Therefore (and also as a result of a large number of tiny particles of volcanic ash in the upper atmosphere, which also make it difficult for sunlight to reach the planet), significant climate changes can occur after especially strong volcanic eruptions. For example, as a result of the eruption of the Ksudach volcano (Kamchatka Peninsula, 1907), an increased concentration of dust in the atmosphere persisted for about 2 years, and characteristic silvery clouds of sulfuric acid were observed even in Paris. The explosion of the Pinatubo volcano in 1991, which sent 3 10 7 tons of sulfur into the atmosphere, led to the fact that 1992 and 1993 were much colder than 1991 and 1994.
Standards
- Sulfuric acid technical GOST 2184-77
- Sulfuric acid battery. Specifications GOST 667-73
- Sulfuric acid of special purity. Specifications GOST 1422-78
- Reagents. Sulfuric acid. Specifications GOST 4204-77
New Topic: Sulfuric Acid -H 2 SO 4
1. Electronic and structural formulas of sulfuric acid
*S - sulfur is in an excited state 1S 2 2S 2 2P 6 3S 1 3P 3 3d 2
The electronic formula of the sulfuric acid molecule:
Structural formula of the sulfuric acid molecule:
1 H - -2 O -2 O
1 H - -2 O -2 O
2. Receipt:
The chemical processes for the production of sulfuric acid can be represented as the following scheme:
S + O 2 + O 2 + H 2 O
FeS 2 SO 2 SO 3 H 2 SO 4
Sulfuric acid is produced in three stages:
1 stage. Sulfur, iron pyrite or hydrogen sulfide are used as raw materials.
4 FeS 2 + 11 O 2 \u003d 2Fe 2 O 3 + 8SO 2
2 stage. Oxidation of SO 2 to SO 3 with oxygen using a catalyst V 2 O 5
2SO 2 + O 2 \u003d 2SO 3 + Q
3rd stage. Not water is used to convert SO 3 to sulfuric acid. there is a strong heating, and a concentrated solution of sulfuric acid.
SO 3 + H 2 O H 2 SO 4
The result is oleum - a solutionSO 3 in sulfuric acid.
Apparatus circuit diagram(see textbook p.105)
3.Physical properties.
a) liquid b) colorless c) heavy (vitriol) d) non-volatile
d) when dissolved in water, strong heating occurs ( so sulfuric acid must be poured intowater,anot vice versa!)
4. Chemical properties of Sulfuric acid.
|
DilutedH 2 SO 4 |
concentratedH 2 SO 4 |
|
Has all the properties of acids |
Has specific properties |
|
1.Changes the color of the indicator: H 2 SO 4 H + + HSO 4 - HSO 4 - H + +SO 4 2- 2.Reacts with metals standing up to hydrogen: Zn + H 2 SO 4 ZnSO 4 +H 2 3. Reacts with basic and amphoteric oxides: MgO + H 2 SO 4 MgSO 4 +H 2 O 4. Interacts with bases (neutralization reaction) 2NaOH + H 2 SO 4 Na 2 SO 4 + 2H 2 O excess acid forms acidic salts NaOH + H 2 SO 4 NaHSO 4 +H 2 O 5. Reacts with dry salts, displacing other acids from them (this is the strongest and non-volatile acid): 2NaCl+H 2 SO 4 Na 2 SO 4 +2HCl 6. Reacts with salt solutions if an insoluble salt is formed: BaCl 2 +H 2 SO 4 BaSO 4 +2HCl- whitesediment qualitative reaction to an ionSO 4 2- 7. When heated, it decomposes: H 2 SO 4 H 2 O + SO 3 |
1. Concentrated H 2 SO 4 is the strongest oxidizing agent; when heated, it reacts with all metals (except Au and Pt). In these reactions, depending on the activity of the metal and the conditions, S, SO 2 or H 2 S are released For example: Cu+ conc 2H 2 SO 4 CuSO 4 +SO 2 +H 2 O 2.conc. H 2 SO 4 passivates iron and aluminum, therefore it can be transported in steel and aluminum tanks. 3. conc. H 2 SO 4 absorbs water well H 2 SO 4 + H 2 O H 2 SO 4 * 2H 2 O Therefore, it chars organic matter |
5.Application: Sulfuric acid is one of the most important products used in various industries. Its main consumers are the production of mineral fertilizers, metallurgy, and refining of petroleum products. Sulfuric acid is used in the manufacture of other acids, detergents, explosives, medicines, paints, and as electrolytes for lead batteries. (Textbook p.103).
6.Salts of sulfuric acid
Sulfuric acid dissociates in steps
H 2 SO 4 H + + HSO 4 -
HSO 4 - H + +SO 4 2-
therefore, it forms two types of salts - sulfates and hydrosulfates
For example: Na 2 SO 4 - sodium sulfate (medium salt)
Na HSO 4 - sodium hydrogen sulfate (acid salt)
The most widely used are:
Na 2 SO 4 * 10H 2 O - Glauber's salt (used in the production of soda, glass, in medicine and
veterinary medicine.
CaSO 4 * 2H 2 O - gypsum
CuSO 4 * 5H 2 O - copper sulfate (used in agriculture).
Laboratory experience
Chemical properties of sulfuric acid.
Equipment: Test tubes.
Reagents: sulfuric acid, methyl orange, zinc, magnesium oxide, sodium hydroxide and phenolphthalein, sodium carbonate, barium chloride.
b) Fill in the table of observations
