Fundamental concepts of hydrocarbons and Uses of hydrocarbons



Hydrocarbons

Hydrocarbons are compound that contain carbon and hydrogen as elements. It is divided into two classes namely aliphatic and aromatic hydrocarbons.

Aliphatic saturated hydrocarbon

These are otherwise called alkanes. Alkanes are often referred to as paraffins. Alkanes are chemically inert to most reagents. For example, methane, ethanes, propane.

Sources of alkanes

The major sources of alkanes are natural gas and petroleum deposits, which are derived from the decompositions of marine organic compound.

Petroleum

Petroleum is a highly complex mixture of hydrocarbons that must be refined into different fractions to get various lower member hydrocarbons.

Combustion

Reaction with oxygen occurs during combustion in an engine of furnace, when the alkane is used as a fuel. Co2 and H2 O are formed as products and a large amount of heat is released.

Liquid petroleum gas

The propane – butane fractions are separated from the more volatile components by liquefaction. These fractions are filled in cylinder as cooking gas.

Natural gas

It contains 80% methane, 10% ethane and 10% a mixture of higher gaseous hydrocarbons.

Crude oil

Crude oil is a mixture of gaseous, liquid and solid hydrocarbons. The hydrocarbons present in the crude oil are paraffins, naphthalene, olefin and aromatic compound in verifying percentage. It is separated by process known as refining of petroleum.

Refining petroleum

Refining of petroleum involves the separation of crude oil into various fractions with different boiling point.

The various fractions coming out of the increasing temperature are orderly described in ascending order below:

Gaseous hydrocarbon
Petroleum ether
Gasoline
Kerosene
Diesel oil fuel for diesel engine
Lubricating oil and grease
Paraffin wax

Tetra ethyl lead

The anti – knocking property of the petrol samples is increased by adding tetra ethyl lead. The anti knocking property is due to the increase in the octane number of petroleum sample. Now the mixing of TEL is considered to be air pollution.

Aliphatic unsaturated compounds

Alkenes and alkynes are aliphatic unsaturated compounds. Alkenes are hydrocarbons that contain carbon – carbon double bond as function group. They are also known as olefins. For example C2 H4

Butylenes

Ethylene is used for ripening of fruits.

Ethylene and propylene are important industrial organic chemicals. They are used in the synthesis of polymers like polythene, PVC, Polystyrene, Teflon, Polyvinyl acetate, polyvinyl alcohol, acrilan.

Polymerization

A polymer is simply a large molecule built up by many smaller units caller monomers. Conversion of a large number of monomers into a single polymer is known as polymerization.

When ethylene is heated under pressure in presence in presence of oxygen, a compound of high molar mass known as polythene is formed.



Plastics

It is the cross linked polymers
For example Bakelite (phenol and formaldehyde)
Vinyl plastic (PVC or PVA)
Polymers are stable, cheap, hard materials.

Natural rubber

Natural rubber is a linear polymer of isoprene. Natural rubber is extracted from latex of Hevea brasilienni.

Synthetic rubber

Synthetic rubber is obtained by polymerization of chloroprene, isobutylene and styrene – butadene mixture.

Alkynes

Alkynes are hydrocarbons that contain a carbon-carbon triple bond. Alkynes are also called acetylenes.

Polymerization of alkynes

When alkynes are passed through red hot iron tube under pressure, they polymerise to aromatic compounds. For example acetylene polymerises to benzene.

Use of alkynes

Acetylene is used in oxy acetylene torch for welding and cutting metals.
Acetylene is used as starting material for manufacture of PVC, synthetic rubber PVA, benzene etc.

Aromatic hydrocarbons

We use the term aromatic to refer to benzene and its structural homologous. Many compounds isolated from natural sources are aromatic in part. For example Benzens. Tolunes, banzaldehyde, estrone, morphine etc.

Coal

Coal is a complex substance made of primarily large array of highly unsaturated benzene like rings linked together.

Coal Tar

When coal is heated to 10000 C in the absence of air, thermal break down of coal molecules occur and a mixture of volatile product called coal tar distills off. The coal tar forms the source of many organic compounds namely, benzene, toluene, naphthalene etc.

Uses of Benzene and Tolune

Benzene is a good solvent of resins and fats.

Benzene is used in dry cleaning.

Toluene is used for blending petrol.

Toluene is used as a solvent for paints, rubber and resins.

Toluene is used to prepare 2, 4, 6 trinitrotoluene which is an explosive.

Rocket fuels

Fuels used in the rockets are called rocket propellent.

Fuel when ignited undergoes combustion to release great quantities of hot gases.

The passage of gases through the nozzle of the motor provides the necessary thrust to move forward, according to Newton’s third law of motion.

Fundamental concepts of hydrocarbons and Uses of hydrocarbons Fundamental concepts of hydrocarbons and Uses of hydrocarbons Reviewed by knowledge people creators on April 10, 2020 Rating: 5
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