Natural gas: the formula. Chemical formula of gas. All types of natural gas

Today, many different gases are known. Some of them a person receives in laboratory ways, from chemicals, some are formed as a result of reactions as by-products. And what gases are born in nature? The main such gases of natural, natural origin are four:

• Natural gas, the formula of which is CH ₄ ;
• Nitrogen, N ₂ ;
• Hydrogen, H ₂ ;
• Carbon dioxide, CO ₂ .

Of course, there are some others - oxygen, hydrogen sulphide, ammonia, inert gases, carbon monoxide. However, the listed above are practically significant for people and are used by them for different purposes, including as fuel.

What is natural gas?

Natural is the kind of gas that nature gives us. That is, the one whose content in the bowels of the Earth is much higher and greater than the amount that it receives in industry as a result of chemical reactions.

It is customary to call natural gas methane, but this is not entirely true. If we consider the composition of such gas by fractions, we can see its following component composition:

• Methane (up to 96%);
• ethane;
• propane;
• butane;
• hydrogen;
• carbon dioxide;
• nitrogen;
• Hydrogen sulphide (small, trace amounts).

Thus, it appears that natural gas is a mixture of several gases of natural origin.

Natural Gas: Formula

From a chemical point of view, natural gas is a mixture of simple linear hydrocarbons - methane, ethane, propane and butane. But since a larger volume is still methane, it is common practice to express the general formula of natural gas with the formula directly methane. So, it turns out that the chemical formula of natural gas methane-CH ₄ .

The remaining components have the following empirical formulas in chemistry:

• Ethane - C ₂ H ₆ ;
• Propane-C ₃ H ₈ ;
• Butane-C ₄ H ₁₀ ;
• Carbon dioxide - СО ₂ ;
• Nitrogen - N ₂ ;
• Hydrogen-H ₂ ;
• Hydrogen sulphide - H ₂ S.

A mixture of such substances is a natural gas. The formula of its main methane compound shows that the carbon content in it is very small. This affects its physical properties, for example, such as the ability to burn with a colorless, completely non-smoking flame. While other representatives of its homologous series (a number of saturated hydrocarbons or alkanes) form a black smoky flame during combustion.

Being in nature

In nature, this gas is found deep underground, under thick and dense layers of sedimentary rocks. There are two main theories of the origin of natural gas in nature.

1. The theory of tectonic movements of rocks. Supporters of this theory believe that hydrocarbons are contained in the earth's interior always and rise as a result of tectonic movements and cuts up. At the top, high pressure and a changing temperature transform them as a result of chemical reactions into two natural minerals - oil and gas.
2. The biogenic theory speaks of another method, which resulted in the formation of natural gas. Its formula reflects the qualitative composition - carbon and hydrogen, which indicates that its formation involved living organic beings, the bodies of which were mostly built from these elements, like all living things on our planet that exist up to now. With the passage of time the dead remains of animals and plants descended ever lower to the ocean floor, where there was no oxygen or bacteria capable of decomposing and processing this organic mass. As a result of anaerobic oxidation, the biomass disintegrated, and for two million years, two sources of minerals - oil and gas - were formed. At the same time, the basis of both is the same - hydrocarbons and partially low-molecular substances. The chemical formula of gas and oil proves this. However, under the influence of different conditions, different products are formed: high pressure and temperature - gas, low indicators - oil.

To date, the main deposits and gas reserves are countries such as Russia, the United States, Canada, Iran, Norway and the Netherlands.

According to its aggregate state, natural gas can not always be contained only in the state of gas. There are several options for its condensation:

1. The gas is dissolved in oil molecules.
2. The gas is dissolved in water molecules.
3. The gas forms solid gas hydrates.
4. Under normal conditions, a gaseous compound.

Each of these states has its own deposit and is very valuable to humans.

Obtaining in the laboratory and industry

In addition to the natural places of gas formation, there are a number of ways to get it in the laboratory. However, these methods, of course, are only used for small portions of the product, since it is not profitable to economically realize the synthesis of natural gas in the laboratory.

Laboratory methods:

1. Hydrolysis of a low-molecular compound - aluminum carbide: AL ₄ C ₃ + 12H ₂ O = 3CH ₄ + 4AL (OH) _3.
2. From sodium acetate in the presence of alkali: CH ₃ COOH + NaOH = CH ₄ + Na ₂ CO _3.
3. From the synthesis gas: CO + 3H ₂ = CH ₄ + H ₂ O.
4. Of simple substances - hydrogen and carbon - at elevated temperature and pressure.

The chemical formula of natural gas is reflected by the formula of methane, therefore all reactions characteristic of alkanes are characteristic for a given gas.

In industry, methane is extracted from natural deposits and further processed by fractions. Also, the gas produced necessarily needs to be cleaned. After all, the methane natural gas formula shows only a part of those components that it contains. And for household use, you need a clean gas that does not contain other substances, except methane. Separated ethane, propane, butane and other gases also find wide application.

Physical properties

The gas formula gives an idea of what physical properties it should possess. Let's consider, what are these characteristics.

1. A colorless substance that does not have a smell.
2. The approximate density varies between 0.7-1 kg / m ^3.
3. The combustion temperature is 650 ^° C.
4. Almost twice as lighter than air.
5. The heat released by burning one cubic meter of gas is 46 million Joules.
6. In high concentrations (over 15%) in the air, the gas is very explosive.
7. When used as fuel, it exhibits an octane number of 130.

Clean gas is obtained only after passing it through special treatment plants (installations), which are erected at the site of extraction of the mineral.

Application

There are several main areas of application of natural gas. In addition to its main component, the gas formula of which CH ₄ , all other components of the mixture are also used.

1. Household sphere of people's life. This includes gas for cooking, heating of residential buildings, fuel for boiler rooms and so on. To the gas used for cooking, add special substances belonging to the group of mercaptans. This is done so that in the event of a pipe or other omission of gas flowing, people can smell it and take action. A mixture of domestic gas (a mixture of propane and butane) is extremely explosive at high concentrations. Mercaptans also make natural gas unpleasant. Their formula includes elements such as sulfur and phosphorus, which gives them this specificity.

2. Chemical production. In this area, one of the main initial substances for many reactions to obtain important compounds is natural gas, the formula of which shows in which syntheses it can participate:

• Basis for the production of plastics, which are the most common modern material for almost all industries;
• Raw materials in the synthesis of ethane, hydrogen cyanide and ammonia. The products themselves go on to manufacture many synthetic fibers and fabrics, fertilizers and heaters in construction in the future;
• Rubber, methanol, organic acids - are formed from methane and other substances. They find application practically in all spheres of human life;
• Polyethylene and many other compounds of a synthetic nature were produced thanks to methane.

3. Use as a fuel. And for any type of human activity, ranging from refilling the appropriate type of table lamps and before the operation of thermal power plants. This type of fuel is considered environmentally sound and expedient against all alternative methods. However, during combustion, methane forms carbon dioxide, like any other organic matter. And it is known to cause the greenhouse effect of the Earth. Therefore, people are faced with the task of finding an even cleaner and qualitative source of thermal energy.

So far, these are all the main sources that use natural gas. His formula, if we take all the complex components, shows that it is a practically renewable resource, only a very long time is needed for this. Our country with gas reserves is extremely lucky, because such a quantity of natural fossil is enough for many hundreds of years not only for Russia itself, but also for many countries of the world through export.

Nitrogen

It is an integral part of oil and gas natural deposits. In addition, this gas occupies most of the volume in the air (78%), and also occurs as natural compounds of nitrate in the lithosphere.

As a simple substance, nitrogen is practically not used by living organisms. Its formula has the form N ₂ , or, from the point of view of chemical bonds, N≡N. The presence of such a strong bond indicates the high stability and chemical inertness of the molecule under normal conditions. This explains the possibility of the existence of a large amount of this gas in a free form in the atmosphere.

In the form of a simple substance, nitrogen can be fixed by special organisms - nodule bacteria. They then process into a more suitable form for plants this gas and thus carry out the mineral nutrition of the root plant systems.

There are several basic compounds in the form of which there is nitrogen in nature. Their formula is as follows:

• Oxides - NO _2, N ₂ O, N ₂ O _5;
• Acids - nitrogenous HNO ₂ and nitric HNO ₃ (formed during lightning discharges from oxides in the air atmosphere);
• Nitrate - KNO ₃ , NaNO ₃ and so on.

Man uses nitrogen not only in the form of gas, but also in a liquid state. It has the ability to go into a liquid state at a temperature below -170 ⁰ C, which allows it to be used to freeze plant and animal tissues, many materials. This is why liquid nitrogen is widely used in medicine.

Also, nitrogen is the basis for obtaining one of its main compounds - ammonia. The production of this substance is multitonous, as it is very widely used in everyday life and industry (production of rubbers, dyes, plastics, synthetic fibers, organic acids, paint and varnish, explosives, etc.).

Carbon dioxide

What is the formula for the substance? Carbon dioxide is recorded as CO ₂ . The bond in the molecule is covalent weakly polar, double strong chemical forces between carbon and oxygen. This indicates the stability and inertness of the molecule under ordinary conditions. This fact is confirmed by the free existence of carbon dioxide in the Earth's atmosphere.

This substance is an integral part of natural gas and oil, and also accumulates in the upper layers of the planet's atmosphere, causing a so-called greenhouse effect.

A huge amount of carbon dioxide is generated by the combustion of any kind of organic fuel. Whether coal, wood, gas or other fuels, complete combustion leads to the formation of water and this substance.

Hence it turns out that its accumulation in the atmosphere is inevitable. Therefore, an important task of modern society is to search for an alternative fuel that gives the minimum greenhouse effect.

Hydrogen

Another incidental compound that occurs in the composition of natural minerals is hydrogen. Gas, the formula of which is H ₂ . The easiest substance of all known to date.

Due to its special properties, it occupies two positions in the periodic table - among alkali metals and halogens. Having one electron, it is capable of giving it away (metal properties, reducing), and take (non-metallic properties, oxidizing).

The main area of use is environmentally friendly fuel, for which scientists see the future. Causes:

• Unlimited amount of stocks of this gas;
• The formation of only water as a result of combustion.

However, the full technology of developing hydrogen as a source of energy requires the completion of many more nuances.

Formulas for calculating the mass, density and volume of gases

In physics and chemistry, several basic methods for calculating gases are used. So, for example, if we are talking about one of the most basic parameters, such as the mass of gas, the formula for calculation will be as follows:

M = V * þ, where þ is the density of matter, and V is its volume.

For example, if we need to calculate the mass of natural gas of 1 cubic meter under normal conditions, then we take the standard average value of its density in the reference materials. It will be equal to 0.68 kg / m ³ . Now that we know the volume and density of the gas, the calculation formula fully meets the requirements. Then:

M (CH ₄ ) = 0.68 kg / m ³ * 1 m ³ = 0.68 kg, as the cubic meters are reduced.

The formula for the volume of gas, on the contrary, consists of the mass and density indices. That is, we can express this value from the above configuration:

V = m / þ, then under standard conditions the volume of 2 kg of methane will be equal to: 2 / 0,68 = 2,914 m ³ .

Also in more complex cases (when conditions are nonstandard), the Mendeleev-Clapeyron equation is used to calculate the mass and volume of gases, which has the form:

P * V = m / M * R * T, where p is the gas pressure, V is its volume, m and M are the mass and molar mass, respectively, R is the universal gas constant equal to 8,314, and T is the temperature in Kelvin.

Such a gas volume formula makes it possible to obtain calculations very approximate to the value of an ideal gas that exists purely hypothetically and is used for an abstract concept in solving problems in physics and chemistry. You can also calculate the volume using the Boyle-Mariotte equation, which looks like this:

V = p _н * V _н * T / p * T _н , where the values with the index n are values under normal standard conditions.

To make the calculation as accurate as possible and correspond to reality, it is necessary to take into account such a parameter as the gas density. The formula for calculating this parameter is still a controversial issue. It is customary to use the most common simple, which looks like:

Þ = m ₀ * n, where m ₀ is the mass of the molecule (kg), and n is the concentration, unit of measurement is 1 / m ³ .

However, in some cases it is necessary to use other, more complex and complete calculations with several variables to obtain an accurate and close to ideal result.