Main types of gases

Nature knows the three basic states of any substance: solid, liquid and gaseous. Virtually any liquid can find each of the remaining two. Many solids can be added to the air during melting, evaporation or combustion. But not every gas can become a component of solid materials or liquids. Various types of gases are known, which differ in their properties, origin and application.

Definition and properties

Gas is a substance for which the absence or minimum value of intermolecular bonds is characteristic, as well as the active mobility of the particles. The main properties that all types of gases have:

1. Fluidity, deformability, volatility, the desire for maximum volume, the reaction of atoms and molecules to a decrease or increase in temperature, which is manifested by a change in the intensity of their movement.
2. There are at a temperature in which the increase in pressure does not lead to a transition to the liquid state.
3. Easily shrink, decreasing in volume. This makes it easier to transport and use.
4. Most are liquefied by compression within certain limits of pressures and critical values of heat.

Due to the research inaccessibility, they are described by means of such basic parameters as temperature, pressure, volume, molar mass.

Classification by deposit

In the natural environment, all types of gases are in the air, the earth and in the water.

1. Composite air: oxygen, nitrogen, carbon dioxide, argon, nitrogen oxide with admixtures of neon, krypton, hydrogen, methane.
2. In the earth's crust, nitrogen, hydrogen, methane and other hydrocarbons, carbon dioxide, sulfur oxide And the others are in gaseous and liquid state. There are also gas deposits in the solid fraction mixed with water layers at pressures of about 250 atm. At relatively low temperatures (up to 20 ° C).
3. The reservoirs contain soluble gases - hydrogen chloride, ammonia and poorly soluble - oxygen, nitrogen, hydrogen, carbon dioxide and etc.

Natural reserves far exceed the possible number of artificially created.

Classification by degree of flammability

All types of gases, depending on the behavioral characteristics in the processes of ignition and combustion, are divided into oxidants, inert and combustible.

1. Oxidizers promote ignition and support combustion, but do not burn themselves: air, oxygen, fluorine, chlorine, oxide and nitrogen dioxide.
2. The inert do not participate in combustion, but they have the property to displace oxygen and influence the decrease in the intensity of the process: helium, neon, xenon, nitrogen, argon, carbon dioxide.
3. Combustible ignite or explode, connecting with oxygen: methane, ammonia, hydrogen, acetylene, propane, butane, carbon monoxide, ethane, ethylene. Most of them are characterized by combustion only under conditions of a certain composition of the gas mixture. Due to this property, gas is a type of fuel, today it is the most common. In this capacity, methane, propane, butane are used.

Carbon dioxide and its role

It is one of the most common gases in the atmosphere (0.04%). At normal temperature and atmospheric pressure has a density of 1.98 kg / m ³ . Can be in a solid and liquid state. The solid phase occurs with negative heat and constant atmospheric pressure, it is called "dry ice". The liquid phase of CO ₂ is possible with increasing pressure. This property is used for storage, transportation and technological applications. Sublimation (transition to a gaseous state from a solid, without an intermediate liquid phase) is possible at -77 - -79 ° C. Solubility in water in the ratio 1: 1 is realized at t = 14-16 ° C.

The types of carbon dioxide are different depending on the origin:

1. Products of vital activity of plants and animals, volcanic emissions, gas emissions from the earth's interior, evaporation from the surface of water bodies.
2. The results of human activities, including emissions from the combustion of all types of fuel.

As a useful substance, it is applied:

1. In carbon dioxide fire extinguishers.
2. In cylinders for arc welding in an appropriate environment of CO ₂ .
3. In the food industry as a preservative and for carbonation of water.
4. As a coolant for temporary cooling.
5. In the chemical industry.
6. In metallurgy.

Being an indispensable component of the life of the planet, man, the work of machines and whole plants, carbon dioxide accumulates in the lower and upper layers of the atmosphere, delaying the release of heat and creating a "greenhouse effect".

Liquefied gas and its role

Among substances of natural origin and technological purpose, those that have a high degree of flammability and calorific value are isolated. The following types of liquefied gas are used for storage, transport and use: methane, propane, butane, as well as propane-butane mixtures.

Butane (C ₄ H ₁₀₎ and propane are components of petroleum gases. The first is liquefied at -1 - -0.5 ° C. Transport and use in the frosty weather of pure butane is not carried out due to its freezing. The liquefaction temperature for propane (C ₃ H ₈₎ -41 - -42 ° C, the critical pressure - 4.27 MPa.

Methane (CH ₄₎ - the main constituent of natural gas. Types of gas source - oil deposits, products of biogenic processes. Liquefaction occurs by means of step-by-step compression and reducing heat to -160 - -161 ° C. At each stage it is compressed 5-10 times.

Liquefaction is carried out at special plants. Propane, butane, as well as their mixture for domestic and industrial use, are produced separately. Methane is used in industry and in the form of fuel for transport. The latter can also be produced in compressed form.

Compressed gas and its role

Recently, compressed natural gas has gained popularity. If propane and butane are exclusively liquefied, methane can be produced in both liquefied and compressed form. Gas in high-pressure cylinders at 20 MPa has several advantages over the well-known liquefied gas.

1. High evaporation rate, including at negative air temperatures, absence of negative accumulation phenomena.
2. Lower toxicity.
3. Full combustion, high efficiency, no negative impact on equipment and atmosphere.

Increasingly, it is used not only for trucks, but also for cars, as well as for boiler equipment.

Gas is a subtle, but indispensable substance for human life. The high calorific value of some of them justifies the wide use of various components of natural gas as fuel for industry and transport.