The main types of gases

Nature knows three basic states of any substance: solid, liquid, and gaseous. Almost any liquid can get each of the remaining two. Many solids can replenish air when melted, vaporized, or burned. But not every gas can become a component of solid materials or liquids. Different types of gases are known which differ in their properties, origin and application features.

Definition and properties

A gas is a substance characterized by the absence or minimum value of intermolecular bonds, as well as the active mobility of 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 lower or increase the temperature, which is manifested by a change in the intensity of their movement.
2. They exist at a temperature under which an increase in pressure does not lead to a transition to a liquid state.
3. Easy to compress, decreasing in volume. This simplifies transportation and use.
4. Most are liquefied by compression within certain pressure and critical heat limits.

Due to research inaccessibility, they are described using the following basic parameters: temperature, pressure, volume, molar mass.

Classification by field

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

1. Compounds of air: oxygen, nitrogen, carbon dioxide, argon, nitric oxide with impurities of neon, krypton, hydrogen, methane.
2. In the earth’s crust, nitrogen, hydrogen, methane and other hydrocarbons, carbon dioxide, sulfur oxide and others are in a 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. Water bodies 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.

Flammability classification

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

1. Oxidizing agents promote ignition and maintain combustion, but do not burn themselves: air, oxygen, fluorine, chlorine, oxide and nitrogen dioxide.
2. Inert ones do not participate in combustion, however, they tend to displace oxygen and influence the decrease in the intensity of the process: helium, neon, xenon, nitrogen, argon, carbon dioxide.
3. Combustible ignites or explodes when combined with oxygen: methane, ammonia, hydrogen, acetylene, propane, butane, carbon monoxide, ethane, ethylene. Most of them are characterized by combustion only in conditions of a certain composition of the gas mixture. Due to this property, gas is a type of fuel, by far the most common. In this quality, 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, it has a density of 1.98 kg / m ³ . May be in 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 a ratio of 1: 1 is realized at t = 14-16 ° C.

Types of carbon dioxide are distinguished depending on the origin:

1. Vital products of plants and animals, volcanic emissions, gas emissions from the bowels of the earth, 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 used:

1. In carbon dioxide fire extinguishers.
2. In cylinders for arc welding in the corresponding environment of CO ₂ .
3. In the food industry as a preservative and for carbonating water.
4. As a refrigerant 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 entire factories, 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 for technological purposes, those that have a high degree of combustibility and calorific value are distinguished. The following types of liquefied gas are used for storage, transportation 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 liquefies at -1 - -0.5 ° C. The transportation and use of pure butane in frosty weather is not carried out due to its freezing. The liquefaction temperature for propane (C ₃ H _{8) is} -41 to -42 ° C, and the critical pressure is 4.27 MPa.

Methane (CH ₄₎ is the main component of natural gas. The types of gas source are oil deposits, products of biogenic processes. Liquefaction takes place by means of stage-by-stage compression and reduction of heat to -160 - -161˚. 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 separately, are produced. Methane is used in industry and as a fuel for vehicles. 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 forms. Gas in cylinders under high pressure of 20 MPa has several advantages over the well-known liquefied.

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

It is increasingly being used not only for trucks, but also for cars, as well as for boiler equipment.

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