THE 7 USES AND APPLICATIONS OF THE MAIN ALKANES - CHEMISTRY - 2025

Some uses and applications of alkanes are as fuel -gas, gasoline, diesel-, as solvents -pentane, hexane, isohexane and heptane-, as lubricants or as waxes and paraffins.

Alkanes are compounds that only contain carbon and hydrogen, therefore they are hydrocarbons. They are also known as paraffins or saturated hydrocarbons because the carbon and hydrogen atoms are linked exclusively by single bonds.

Alkanes belong to a homologous series of organic compounds in which the members differ by a constant molecular mass of 14 which is CH ₂. The general formula is CnH _{2n + 2.}

Alkanes contain only single bonds, which means they are saturated with hydrogen atoms. They are the basic hydrocarbons and the starting points to understand the chemistry of other more complex molecules.

Alkanes get their name from the alkyl group which is made up of one carbon and three hydrogens.

Of course, they contain other groups, but they consistently contain an alkyl group. The ending "-ano" lets you know that there are only single bonds in these molecules.

The smallest members of the alkane family are gases, while the largest compounds are liquid and solid compounds.

They are commonly found in fuel sources, such as natural gas and oil. Solid compounds are typically waxy in texture.

Main uses and applications of alkanes

1- Fuel

The main use of alkanes is for fuel. Its oxidation reaction releases energy that can be used to generate electricity, move vehicles or even cook.

Short-chain alkanes, such as methane, ethane, propane and butane are in a gaseous state and we can extract them from natural gas fields.

Methane is used as a vehicle fuel while propane and butane are used as cooking gas.

Longer chain alkanes are in a liquid state and can be found in gasoline or diesel. When talking about high octane, it refers to the octane concentration in the fuel.

2- Solvents

Since the dipole moment between carbon and oxygen is very low, alkanes do not have bond polarity so they serve well as apolar solvents.

Chemists have a maxim that says "similar dissolves similar", this means that polar solvents dissolve polar substances and non-polar or non-polar solvents dissolve non-polar substances.

Compounds such as pentane, hexane, isohexane and heptane are used in the laboratory and in industry as solvents for reactions in a non-polar medium. Nonane is the main component of kerosene.

3- Lubricants

Alkanes with 17 or more carbon molecules are used as lubricants and anticorrosives, since their hydrophobic nature means that water cannot reach the metal surface. Given their density and viscosity, they are perfect for this use.

Lubricating oils of different viscosities can mix with each other, and it is this ability to mix them that makes some oils so useful.

For example, common motor oil is generally a blend of low viscosity oil to allow easy starting in cold temperatures and a high viscosity oil for better performance at normal operating temperatures.

Since Roman times, many liquids, including water, have been used as lubricants to minimize friction, heat, and wear between mechanical parts in contact with each other.

Today, lubricating oil is the most widely used product due to its wide range of possible applications.

4- Waxes and paraffins

Alkanes are also known as paraffins, which makes this term very confusing because paraffin also refers to a type of wax.

To clarify the concepts, any saturated hydrocarbon (with the formula CnH _{2n + 2}) is a paraffin and a mixture of these molecules can be used to make a wax called paraffin wax.

In general, the alkanes used in this wax have carbon chains that contain 20 to 40 carbons. Therefore, paraffin wax is a type of wax made from paraffins or alkanes.

Paraffin wax is characterized by a low melting point, flexible structure, and easy burning. It is generally used in candles and crayons.

5- Asphalt

Asphalt is present in crude oil and consists of a mixture of hydrocarbons, especially chain alkanes of 35 carbons or more. Asphalt has a semi-solid, viscous consistency.

Its main use is the construction of roads because adding sand or gravel to the asphalt produces a solid mixture ideal for this type of use.

When its density is lower, it is also known as pitch and can be used as a waterproofing agent.

6- Chemical reactions

Compared to alkenes and alkynes, alkanes are relatively unreactive due to the absence of a weaker pi bond in their carbon skeletons. However, there are some classes of reactions that are commonly performed with alkanes.

The most important reaction that alkanes undergo is combustion. Smaller linear alkanes are more easily oxidized than larger, more branched molecules.

Alkanes can burn in the presence of oxygen to produce carbon dioxide, water, and energy.

In oxygen-limited situations, the products are carbon monoxide, water, and energy. For this reason, alkanes are frequently used as fuel sources.

C ₃ H ₈ + 5O ₂ »3CO ₂ + 4H ₂ O + energy

A consistent reaction, in addition to combustion, that alkanes undergo is the halogenation of free radicals.

In this process, the hydrogens in alkyl groups are replaced by halogens (molecules like chlorine and bromine on the periodic table). A typical reaction is demonstrated using propane.

2C ₃ H ₈ + Cl ₂ »2C ₃ H ₈ Cl

Complex alkanes with high molecular weights found in crude oil are frequently divided into smaller, more useful alkanes by thermal cracking; Alkenes and hydrogen gas are also produced using this method.

Thermal cracking is typically carried out at high temperatures, and often in the presence of a catalyst. A mixture of products is obtained, and these alkanes and alkenes can be separated by fractional distillation.

7- Other uses of alkanes

Alkanes have other uses apart from those already mentioned. Compounds such as ethane are used for the production of ethylene, which is used to produce ethylene glycol (the main component of antifreeze) and polyethylene, which is the most widely used plastic worldwide.

Propane can be used as a refrigerant when electricity is not available. As the gas expands, it absorbs heat.

In fact, it can cause frostbite. It is also being considered as a replacement for other refrigerants, but has the main drawback of being explosive.

Butane is a euphoric, so it is often abused as an inhalant. Unfortunately, it causes suffocation, cardiac arrhythmia, and spasms of the muscles of the airways in the lungs.

This last property is the cause of the "sudden death of a drug addict", and is the cause of death in 55% of cases related to the inhalation of solvents.

Pentane can be found in gasoline blends, but its primary use in the industrial setting is as a "blower" in creating plastic foams.

Also, like propane, it can be used as a refrigerant. Its isomer, isopentane, is commonly used in toothpastes.

Hexane and isohexane are the preferred solvents in food processing, particularly isohexane, since they are non-toxic and have a neutral pH.

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