Sulfate acid: formula and chemical properties

2024 Author: Angel Austin | [email protected]. Last modified: 2024-01-02 17:39

One of the very first mineral acids that became known to man is sulfuric, or sulfate. Not only she herself, but also many of her s alts were used in construction, medicine, the food industry, and for technical purposes. So far, nothing has changed in this respect. A number of characteristics that sulfate acid possesses make it simply indispensable in chemical syntheses. In addition, its s alts are used in almost all sectors of everyday life and industry. Therefore, we will consider in detail what it is and what are the features of the manifested properties.

Variety of names

Let's start with the fact that this substance has a lot of names. Among them there are those that are formed according to rational nomenclature, and those that have historically developed. So, this connection is designated as:

• sulphate acid;
• vitriol;
• sulfuric acid;
• oleum.

Although the term "oleum" is not quite suitable for this substance, since it is a mixture of sulfuric acid and higher sulfur oxide -SO_3.

Sulfate acid: formula and molecular structure

From the point of view of chemical abbreviation, the formula of this acid can be written as follows: H₂SO_{4. Obviously, the molecule consists of two hydrogen cations and an anion of the acidic residue - sulfate ion, which has a charge of 2+.}

In this case, the following bonds act inside the molecule:

• covalent polar between sulfur and oxygen;
• covalent strongly polar between hydrogen and acid residue SO_4.

Sulfur, having 6 unpaired electrons, forms two double bonds with two oxygen atoms. With a couple more - single, and those, in turn, single with hydrogens. As a result, the structure of the molecule allows it to be strong enough. At the same time, the hydrogen cation is very mobile and easily leaves, because sulfur and oxygen are much more electronegative. By pulling the electron density onto themselves, they provide hydrogen with a partially positive charge, which becomes full when detached. This is how acidic solutions are formed, in which there is H+.

If we talk about the oxidation states of the elements in the compound, then sulfate acid, the formula of which is H₂SO_{4, easily allows you to calculate them: hydrogen +1, oxygen -2, sulfur +6.}

As in any molecule, the total charge is zero.

Discovery history

Sulfate acid has been known to people since antiquity. Even alchemists knew how to get it by calcining various vitriol. WithAs early as the 9th century, people received and used this substance. Later in Europe, Albert Magnus learned how to extract acid from the decomposition of iron sulfate.

However, none of the methods were profitable. Then the so-called chamber version of synthesis became known. For this, sulfur and nitrate were burned, and the released vapors were absorbed by water. As a result, sulfate acid was formed.

Even later, the British managed to find the cheapest method of obtaining this substance. Pyrite was used for this - FeS_{2, iron pyrites. Its roasting and subsequent interaction with oxygen still constitute one of the most important industrial methods for the synthesis of sulfuric acid. Such raw materials are more affordable, cheaper and of higher quality for large volumes of production.}

Physical properties

There are several parameters, including external ones, which distinguish sulfate acid from others. Its physical properties can be described in several points:

1. Liquid under standard conditions.
2. In its concentrated state, it is heavy, oily, for which it received the name "vitriol".
3. Density of matter - 1.84 g/cm3.
4. No color or odor.
5. It has a pronounced "copper" taste.
6. Dissolves very well in water, almost unlimited.
7. Hygroscopic, capable of trapping both free and bound water from tissues.
8. Non-volatile.
9. Boiling point - 296oC.
10. Melting at 10, 3oC.

One of the most important features of this compound is the ability to hydrate with the release of a large amount of heat. That is why, even from the school bench, children are taught that it is by no means possible to add water to acid, but only the other way around. After all, water is lighter in density, so it will accumulate on the surface. If it is abruptly added to acid, then as a result of the dissolution reaction, such a large amount of energy will be released that the water will boil and begin to splatter along with particles of a dangerous substance. This can cause severe chemical burns to the skin of the hands.

Therefore, acid should be poured into water in a thin stream, then the mixture will become very hot, but boiling will not occur, which means that the liquid will also splash.

Chemical properties

From the point of view of chemistry, this acid is very strong, especially if it is a concentrated solution. It is dibasic, therefore it dissociates in steps, with the formation of hydrosulfate and sulfate anions.

In general, its interaction with various compounds corresponds to all the main reactions characteristic of this class of substances. We can give examples of several equations in which sulfate acid takes part. Chemical properties are manifested in its interaction with:

• s alts;
• metal oxides and hydroxides;
• amphoteric oxides and hydroxides;
• metals standing in a series of voltages up to hydrogen.

Bas a result of such interactions, in almost all cases, medium s alts of a given acid (sulfates) or acidic s alts (hydrosulfates) are formed.

A special feature is also that with metals according to the usual scheme Me + H₂SO₄=MeSO ₄ + H_{2↑ only a solution of a given substance reacts, that is, a dilute acid. If we take concentrated or highly saturated (oleum), then the interaction products will be completely different.}

Special properties of sulfuric acid

These include just the interaction of concentrated solutions with metals. So, there is a certain scheme that reflects the whole principle of such reactions:

1. If the metal is active, the result is the formation of hydrogen sulfide, s alt and water. That is, sulfur is reduced to -2.
2. If the metal is of medium activity, then the result is sulfur, s alt and water. That is, the reduction of the sulfate ion to free sulfur.
3. Metals of low reactivity (after hydrogen) - sulfur dioxide, s alt and water. Sulfur in oxidation state +4.

Also, the special properties of sulfate acid are the ability to oxidize some non-metals to their highest oxidation state and react with complex compounds and oxidize them to simple substances.

Methods of obtaining in the industry

The sulfate process for producing sulfuric acid consists of two main types:

• contact;
• tower.

Both are the most common ways inindustry in all countries of the world. The first option is based on the use of iron pyrite or sulfur pyrite as a raw material - FeS_{2. There are three stages in total:}

1. Roasting of raw materials with the formation of sulfur dioxide as a combustion product.
2. Passing this gas through oxygen over a vanadium catalyst to form sulfuric anhydride - SO_3.
3. In the absorption tower, anhydride is dissolved in a solution of sulfate acid with the formation of a high concentration solution - oleum. Very heavy oily thick liquid.

The second option is practically the same, but nitrogen oxides are used as a catalyst. From the point of view of such parameters as product quality, cost and energy consumption, purity of raw materials, productivity, the first method is more efficient and acceptable, so it is more often used.

Laboratory synthesis

If it is necessary to obtain sulfuric acid in small quantities for laboratory research, then the method of interaction of hydrogen sulfide with sulfates of low-active metals is best suited.

In these cases, the formation of ferrous metal sulfides occurs, and sulfuric acid is formed as a by-product. For small studies, this option is suitable, but such an acid will not differ in purity.

Also in the laboratory you can conduct a qualitative reaction to sulfate solutions. The most common reagent is barium chloride, since the Ba²⁺ ion, together withsulfate anion precipitates into a white precipitate - barite milk: H₂SO₄ + BaCL₂=2HCL + BaSO_4↓

The most common s alts

Sulfate acid and the sulfates it forms are important compounds in many industries and households, including food. The most common s alts of sulfuric acid are:

1. Gypsum (alabaster, selenite). The chemical name is an aqueous calcium sulfate crystalline hydrate. Formula: CaSO_{4. Used in construction, medicine, pulp and paper, jewelry making.}
2. Barite (heavy spar). barium sulfate. In solution, it is a milky precipitate. In solid form - transparent crystals. Used in optical instruments, X-rays, insulating coating.
3. Mirabilite (Glauber's s alt). The chemical name is sodium sulfate decahydrate. Formula: Na₂SO₄10H_{2O. Used in medicine as a laxative.}

There are many examples of s alts that have practical significance. However, the ones mentioned above are the most common.

Sulfate lye

This substance is a solution that is formed as a result of the heat treatment of wood, that is, cellulose. The main purpose of this compound is to obtain sulfate soap on its basis by settling. The chemical composition of sulfate liquor is as follows:

• lignin;
• hydroxy acids;
• monosaccharides;
• phenols;
• resin;
• volatile and fatty acids;
• sulfides, chlorides, carbonates and sulfates of sodium.

There are two main types of this substance: white and black sulfate liquor. The white goes to the pulp and paper industry, while the black is used to make sulfate soap in the industry.

Main applications

The annual production of sulfuric acid is 160 million tons per year. This is a very significant figure, which indicates the importance and prevalence of this compound. There are several industries and places where the use of sulfate acid is necessary:

1. In batteries as an electrolyte, especially in lead ones.
2. In factories where sulfate fertilizers are produced. The bulk of this acid is used specifically for the manufacture of mineral fertilizers for plants. Therefore, plants for the production of sulfuric acid and the manufacture of fertilizers are most often built side by side.
3. In the food industry as an emulsifier, indicated by code E513.
4. In numerous organic syntheses as a dewatering agent, a catalyst. This is how explosives, resins, cleaning and detergents, nylons, polypropylene and ethylene, dyes, chemical fibers, esters and other compounds are obtained.
5. Used in filters to purify water and make distilled water.
6. Used in the extraction and processing of rare elements from ore.

Also a lot of chamoisacid goes to laboratory research, where it is obtained by local methods.