Main types of gases

2024 Author: Howard Calhoun | [email protected]. Last modified: 2024-01-02 13:48

Nature knows three basic states of any substance: solid, liquid and gaseous. Almost any liquid can acquire each of the remaining two. Many solids, when melted, evaporated, or burned, can replenish the contents of the air. 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

Gas is a substance characterized by the absence or minimum value of intermolecular bonds, as well as the active mobility of particles. Basic properties that all types of gases have:

1. Fluidity, deformability, volatility, striving 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. Exist at a temperature where an increase in pressure does not liquefy.
3. Easyshrink, decreasing in volume. This makes it easy to transport and use.
4. Most are liquefied by compression within certain limits of pressure and critical heat values.

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

Classification by deposit

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

1. Components 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˚С).}
3. Reservoirs contain soluble gases - hydrogen chloride, ammonia and poorly soluble gases - oxygen, nitrogen, hydrogen, carbon dioxide _etc.

Natural reserves far exceed the possible amount 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 oxidizers, inert and combustible.

1. Oxidants promote and support combustion, but do not burn themselves: air, oxygen, fluorine, chlorine, nitrogen oxide and dioxide.
2. Inert do not participatein 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. Combustibles ignite or explode when combined 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 the type of fuel, by far the most common. Methane, propane, butane are used in this capacity.

Carbon dioxide and its role

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/m³. May be in solid or liquid state. The solid phase occurs at negative heat and constant atmospheric pressure, it is called "dry ice". The liquid phase 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˚С. Solubility in water in a ratio of 1:1 is realized at t=14-16˚С.}

Types of carbon dioxide are distinguished depending on the origin:

1. The waste products of plants and animals, emissions from volcanoes, gas emissions from the bowels of the earth, evaporation from the surface of water bodies.
2. Human output, including emissions from combustion of all kindsfuel.

As a useful substance, it is used:

1. In carbon dioxide fire extinguishers.
2. In cylinders for arc welding in the appropriate environment CO_2.
3. In the food industry as a preservative and for carbonation of 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 operation 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 the substances of natural origin and technological purposes, there are those that have a high degree of flammability and calorific value. The following types of liquefied gas are used for storage, transportation and use: methane, propane, butane, as well as propane-butane mixtures.

Butane (C₄H₁₀₎ and propane are components of petroleum gases. The first liquefies at -1 - -0, 5˚С. Transportation and use in frosty weather of pure butane is not carried out due to its freezing. Liquefaction temperature for propane (С₃Н_{8) -41 – -42˚С, critical pressure – 4.27 MPa.}

Methane (CH_{4) is the main constituent of natural gas. Types of gas source - oil deposits, products of biogenic processes. Liquefaction occurs through gradual compression and heat reduction to -160 - -161˚С. On eachstage 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 as a fuel for transport. The latter can also be issued in compressed form.

Compressed gas and its role

Recently, compressed natural gas has gained popularity. If only liquefaction is used for propane and butane, then methane can be produced both in a liquefied and in a compressed state. Gas in cylinders under high pressure of 20 MPa has a number of advantages over the well-known liquefied gas.

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

Increasingly finds application 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 a fuel for industry and transport.