Education, Secondary education and schools
Acids: examples, table. Properties of acids
Acids are such chemical compounds that are capable of giving off an electrically charged ion (cation) of hydrogen, and also accept two interacting electrons, resulting in a covalent bond.
In this article, we will look at the basic acids that are studied in secondary schools of general education schools, and also learn a lot of interesting facts about the most diverse acids. Let's get started.
Acids: Species
In chemistry, there are many different acids that have very different properties. Chemists distinguish between acids in content in the composition of oxygen, in volatility, in solubility in water, strength, stability, belonging to the organic or inorganic class of chemical compounds. In this article, we will consider a table in which the most known acids are presented. The table will help you remember the name of the acid and its chemical formula.
| Chemical formula | Name of acid |
| H 2 S | Hydrogen sulfide |
| H 2 SO 4 | Sernaya |
| HNO 3 | Nitrogen |
| HNO 2 | Nitrogen |
| HF | Plavikovaya |
| HCl | Salt |
| H 3 PO 4 | Phosphoric |
| H 2 CO 3 | Coal |
So, everything is clearly visible. In this table, the most known acids in the chemical industry are shown. The table will help to memorize names and formulas much more quickly.
Hydrogen sulfide
H 2 S is hydrogen sulphide. Its feature is that it is also a gas. Hydrogen sulfide is very poorly dissolved in water, and also interacts with very many metals. Hydrogen sulfide belongs to the group "weak acids", examples of which we will consider in this article.
H 2 S has a slightly sweet taste, as well as a very sharp smell of rotten eggs. In nature, it can be found in natural or volcanic gases, and it is released when the protein is rotten.
The properties of acids are very diverse, even if the acid is indispensable in industry, it can be very unhealthy for human health. This acid is very toxic to humans. When a small amount of hydrogen sulfide is inhaled, a headache develops in the person, severe nausea and dizziness begin. If a person inhales a large amount of H 2 S, it can lead to convulsions, coma or even instant death.
Sulfuric acid
H 2 SO 4 is a strong sulfuric acid, with which children learn chemistry lessons in the 8th grade. Chemical acids, such as sulfuric acid, are very strong oxidants. H 2 SO 4 acts as an oxidizing agent on very many metals, as well as basic oxides.
H 2 SO 4 when exposed to skin or clothing causes chemical burns, but it is not as toxic as hydrogen sulphide.
Nitric acid
Strong acids are very important in our world. Examples of such acids are: HCl, H 2 SO 4 , HBr, HNO 3 . HNO 3 is the known nitric acid. It has found wide application in industry, as well as in agriculture. It is used for the manufacture of various fertilizers, in jewelry, in printing photographs, in the manufacture of drugs and dyes, and in the military industry.
Such chemical acids, like nitric, are very harmful to the body. HNO 3 vapors leave ulcers, cause acute inflammation and irritation of the respiratory tract.
Nitrous acid
Nitrogenous acid is very often confused with nitrogen, but there is a difference between them. The fact is that nitrous acid is much weaker than nitrogen, it has completely different properties and effects on the human body.
HNO 2 has found wide application in the chemical industry.
Hydrofluoric acid
Hydrofluoric acid (or hydrogen fluoride) is a solution of H 2 O c HF. The acid formula is HF. Hydrofluoric acid is very actively used in the aluminum industry. It dissolves silicates, etches silicon, silicate glass.
Hydrogen fluoride is very harmful to the human body, depending on its concentration can be an easy drug. If you get on your skin, first, no changes, but after a few minutes, you may get a sharp pain and a chemical burn. Hydrofluoric acid is very harmful to the environment.
Hydrochloric acid
HCl is hydrogen chloride, is a strong acid. Hydrogen chloride preserves the properties of acids belonging to the strong group. The appearance of the acid is clear and colorless, and smokes in the air. Chloride hydrogen is widely used in the metallurgical and food industries.
This acid causes chemical burns, but it is especially dangerous to hit it in the eyes.
Phosphoric acid
Phosphoric acid (H 3 PO 4 ) is a weak acid in its properties. But even weak acids can have the properties of strong ones. For example, H 3 PO 4 is used in industry to restore iron from rust. In addition, phosphoric (or orthophosphoric) acid is widely used in agriculture - it produces a variety of various fertilizers.
The properties of acids are very similar - almost all of them are very harmful to the human body, H 3 PO 4 is no exception. For example, this acid also causes severe chemical burns, nosebleeds, and tooth decay.
Carbonic acid
H 2 CO 3 is a weak acid. It is obtained by dissolving CO 2 (carbon dioxide) in H 2 O (water). Carbonic acid is used in biology and biochemistry.
Density of various acids
Density of acids occupies an important place in the theoretical and practical parts of chemistry. Due to the knowledge of the density, it is possible to determine the concentration of an acid, solve the calculated chemical problems and add the correct amount of acid for the reaction. The density of any acid varies with concentration. For example, the greater the percentage of concentration, the greater the density.
General properties of acids
Absolutely all acids are complex substances (that is, they consist of several elements of the periodic table), and they necessarily include H (hydrogen) in their composition. Next we will consider the chemical properties of acids, which are common:
- All oxygen-containing acids (in the formula of which there is O) decompose form water, as well as acid oxide. And the anoxic ones decompose into simple substances (for example, 2HF decomposes into F 2 and H 2 ).
- Acid-oxidants interact with all metals in the series of metal activities (only those that are located to the left of H).
- Interact with different salts, but only with those that were formed by an even weaker acid.
According to their physical properties, acids differ sharply from each other. After all, they can have a smell and not have it, and also be in a variety of aggregate states: liquid, gaseous and even solid. Very interesting for studying solid acids. Examples of such acids are C 2 H 2 O 4 and H 3 BO 3 .
Concentration
Concentration is a quantity that determines the quantitative composition of any solution. For example, chemists often need to determine how much pure sulfuric acid is in the dilute acid H 2 SO 4 . To do this, they pour a small amount of diluted acid into a measuring beaker, weigh and determine the concentration according to the density table. The concentration of acids is closely interrelated with the density, often on the determination of the concentration there are calculated problems, where it is necessary to determine the percentage of pure acid in the solution.
The classification of all acids by the number of H atoms in their chemical formula
One of the most popular classifications is the separation of all acids into monobasic, dibasic and, respectively, tribasic acids. Examples of monobasic acids are HNO 3 (nitric), HCl (hydrochloric acid), HF (hydrofluoric acid), and others. These acids are called monobasic because only one H atom is present in their composition. There are a lot of such acids, it is impossible to remember absolutely each one. It is only necessary to remember that the acids are classified according to the number of H atoms in their composition. Dibasic acids are similarly defined. Examples: H 2 SO 4 (sulfuric), H 2 S (hydrogen sulphide), H 2 CO 3 (coal) and others. Three-base: H 3 PO 4 (phosphoric).
Basic classification of acids
One of the most popular classifications of acids is the separation of them into oxygen-containing and oxygen-free. How to remember, without knowing the chemical formula of the substance, that it is an oxygen-containing acid?
All oxygen-free acids in the composition lack an important element O-oxygen, but in the composition there is H. Therefore, the word "hydrogen" is always assigned to their name. HCl is hydrochloric acid, and H 2 S is hydrogen sulphide.
But by the name of acidic acids, you can write a formula. For example, if the number of O atoms in a substance is 4 or 3, then the suffix -n-, and also the ending -aя- is always added to the name:
- H 2 SO 4 - sulfuric (number of atoms - 4);
- H 2 SiO 3 - silicon (number of atoms - 3).
If there are less than three oxygen atoms in the substance or three, then the suffix -ist is used in the name:
- HNO 2 - nitrogenous;
- H 2 SO 3 - sulfurous.
Common Properties
All acids have a sour taste and are often slightly metallic. But there are other similar properties that we will now consider.
There are such substances, which are called indicators. The indicators change their color, or the color remains, but its hue changes. This occurs at a time when some other substances, such as acids, are acting on the indicators.
An example of the color change can serve as a product habitual to many, like tea, and citric acid. When a lemon is thrown into tea, the tea gradually begins to brighten noticeably. This is due to the fact that lemon contains citric acid.
There are other examples. Litmus, which in a neutral environment has a lilac color, turns red when hydrochloric acid is added.
When acid reacts with metals in the series of tension to hydrogen, gas bubbles are released - H. However, if a metal is placed in a test tube with acid, which is in the series of tension after H, then no reaction will occur, there will be no gas evolution. So, copper, silver, mercury, platinum and gold with acids will not react.
In this article, we examined the most famous chemical acids, as well as their main properties and differences.
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