Physical and chemical properties of carbon
Organic life on Earth is represented by carbon compounds. The element is part of the main components of cellular structures: proteins, carbohydrates and fats, and also forms the basis of the substance of heredity - deoxyribonucleic acid. In the inorganic nature of carbon is one of the most common elements that form the crust and atmosphere of the planet. Organic chemistry as a section of chemical science is completely devoted to the properties of the chemical element carbon and its compounds. Our article will consider the physico-chemical characteristics of carbon and the characteristics of its properties.
The place of the element in the periodic system
The carbon subgroup is the main subgroup of the IV group, which, in addition to carbon, also includes silicon, germanium, tin and lead. All the listed elements have the same structure of the external energy level, on which four electrons are located. This causes the similarity of their chemical properties.In the usual state, the elements of the subgroup are bivalent, and when their atoms become excited, they exhibit a valence equal to 4. The physical and chemical properties of carbon depend on the state of the electronic shells of its atom. Thus, in reaction with oxygen, an element whose particles are in an unexcited state forms an indifferent oxide CO. The carbon atoms in the excited state are oxidized to carbon dioxide, which exhibits acidic properties.
Carbon forms in nature
Diamond, graphite and carbin are three allotropic modifications of carbon as a simple substance. Transparent crystals with a high degree of refraction of light rays, which are the hardest compounds in nature, are diamonds. They conduct heat poorly and are dielectrics. The crystal lattice is atomic, very durable. In it, each atom of an element is surrounded by four other particles, forming a regular tetrahedron.
Completely different physico-chemical properties of carbon that forms graphite. It is a greasy, dark-gray crystalline substance. It has a layered structure, the distances between the layers of atoms are quite large,whereas their attraction forces are weak. Therefore, when pressed on a graphite rod, the substance splits into thin scales. They leave a dark mark on the paper. Graphite is conductive and slightly inferior to metals in electrical conductivity.
The ability to conduct an electrical current is explained by the structure of the crystal substance. In it, carbon particles are bound to the other three by strong covalent chemical bonds. The fourth valence electron of each atom remains free and is able to move in the thickness of the substance. The directional movement of negatively charged particles and causes the appearance of an electric current. The applications of graphite are varied. So, it is used for the manufacture of electrodes in electrical engineering and for carrying out the process of electrolysis, with the help of which, for example, alkali metals are obtained in pure form. Graphite has been used in nuclear reactors to control the speed of the chain reactions passing through them as a neutron moderator. It is known to use the substance as a slate rod or lubricant in the rubbing parts of mechanisms.
What is carbin?
Black crystalline powder with a glass shine is carbin.It was synthesized in the middle of the 20th century in Russia. The substance surpasses graphite in hardness, is chemically passive, has the properties of a semiconductor, and is the most stable modification of carbon. The compound is more durable than graphite. There are also forms of carbon whose chemical properties differ from one another. These are soot, charcoal and coke.
Different characteristics of carbon allotropic modifications are explained by the structure of their crystal lattices. It is a refractory substance with no color or odor. It is insoluble in organic solvents, but it is capable of forming solid solutions - alloys, for example, with iron.
Chemical properties of carbon
Depending on the substance with which carbon reacts, it can exhibit dual properties: both a reducing agent and an oxidizing agent. For example, fusing coke with metals, get their compounds - carbides. Hydrocarbons are formed in the reaction with hydrogen. These are organic compounds, for example, methane, ethylene, acetylene, in which, as in the case with metals, carbon has an oxidation state of -4.The reducing chemical reactions of carbon, whose properties we are studying, manifest themselves during its interaction with oxygen, halogens, water, and basic oxides.
Burning coal in low oxygen air produces carbon monoxide, a bivalent carbon dioxide. It is colorless, odorless and highly toxic. Combined with blood hemoglobin during respiration, carbon monoxide spreads throughout the human body, causing poisoning and then death from suffocation. In the classification, the substance takes the place of indifferent oxides, does not react with water, neither base nor acid corresponds to it. The chemical properties of carbon with a valence of 4 differ from the previously considered characteristic.
A colorless gaseous substance at a temperature of 15 and a pressure of one atmosphere turns into a solid phase. It is called dry ice. CO molecules2non-polar, although the covalent bond between the oxygen atoms and the carbon is polar. Connection refers to acid oxides. Interacting with water, it forms carbonate acid.There are reactions between carbon dioxide and simple substances: metals and non-metals, for example, with magnesium, calcium or coke. In them, he plays the role of an oxidizing agent.
Qualitative reaction to carbon dioxide
To ensure that the test gas is indeed carbon monoxide CO2, in inorganic chemistry, the following experiment is carried out: the substance is passed through a clear solution of lime water. The observation of the turbidity of the solution due to the precipitation of white calcium carbonate precipitates the presence of carbon dioxide molecules in the mixture of reagents. With further passage of gas through a solution of calcium hydroxide precipitate CaCO3dissolves due to its conversion to calcium bicarbonate - a water-soluble salt.
The role of carbon in the domain process
The chemical properties of carbon are used in the industrial production of iron from its ores: magnetic, red or brown iron ore. Chief among them will be the reducing properties of carbon and oxides - carbon monoxide and carbon dioxide. The processes occurring in the blast furnace, can be represented as the following sequence of reactions:
- First, coke burns in an air stream heated to 1,850 ° C to form carbon dioxide: C + O2= CO2.
- Passing through hot carbon, it is reduced to carbon monoxide: CO2+ C = 2CO.
- Carbon monoxide reacts with iron ore, resulting in iron oxide: 3Fe2O3+ CO = 2Fe3O4+ CO2Fe, Fe3O4+ CO = 3FeO + CO2↑.
- The reaction of obtaining iron will have the following form: FeO + CO = Fe + CO2
Molten iron dissolves in itself a mixture of carbon and carbon monoxide, it turns out the substance - cementite.
Cast iron smelted in the blast furnace, except iron, contains up to 4.5% carbon and other impurities: manganese, phosphorus, sulfur. Steel, which differs from cast iron by a number of features, for example, its ability to be rolled and forged, has in its composition only 0.3 to 1.7% carbon. Steel products are widely used in almost all industries: engineering, metallurgy, medicine.
In our article, we found out what chemical properties of carbon and its compounds are used in various spheres of human activity.