Petroleum is found in liquid form and can be sourced naturally. It is the result of the decomposition of different organic matter and hence petroleum is referred to as fossil fuel. Petroleum is also known as crude oil. It is a thick, black naturally occurring liquid extracted from the Earth’s crust and can be used as fuel. Petroleum is a fossil fuel that occurs in all three states of matter, i.e. solid, liquid and gas.

The word ‘Petroleum’ is derived from two Latin words, ‘petra’ meaning rock and ‘oleum’ meaning oil. Due to its black colour when extracted, its high cost and its immense importance, petroleum is also known as ‘Black Gold’! With time petroleum products bloomed as one of the world’s major sources of energy due to their easy transportation and high energy-yielding property.

Embibe offers a range of study materials for students studying in the CBSE board. The study materials include PDF of NCERT books, previous year question papers and solution sets. Students can follow these study materials to understand the correct approach that needs to be followed to answer the exercise questions correctly. These solution sets are prepared by a team of experts from Embibe who have a better understanding of the marking scheme and exam pattern followed by CBSE board.

Petroleum: Details

Petroleum is one of the commonly used natural resources that is formed from dead and decayed plants and animals buried inside the Earth’s crust millions of years ago. Under intense pressure and temperature, these fossils turned into complex hydrocarbons known as petroleum products. Though petroleum is a natural resource, it is a non-renewable source of energy.

Petroleum is a fossil fuel which is also referred to as crude oil. Like coal and natural gas, petroleum was also formed from the remains of ancient dead marine organisms, such as plants, algae, and bacteria. Petroleum reservoirs are found mostly beneath land or the ocean floor.

This crude oil is extracted with giant drilling machines. Petroleum products are fuels made from hydrocarbons present in natural gas. Some examples of petroleum products are kerosene, diesel fuel, gasoline, etc.

Petroleum: Chemical Composition

Petroleum is a mixture of volatile liquid hydrocarbons; along with this, it also contains some nitrogen, sulphur, and oxygen:

Carbon	\({\rm{83 – 87\% }}\)
Hydrogen	\({\rm{10 – 14\% }}\)
Nitrogen	\({\rm{0.1 – 2\% }}\)
Oxygen	\({\rm{0.05 – 1\% }}\)
Sulphur	\({\rm{0.05- 6\% }}\)
Metals	Less than \({\rm{0.1\% }}\)

Petroleum: Formation

It gets formed when dead organisms – primarily zooplankton and algae underneath sedimentary rocks get subjected to intense heat and pressure.

Let’s discuss various steps of petroleum formation in detail:

1. Anaerobic Decay

Anaerobic decay is a process through which bacteria break down organic matter such as dead plants and animals in the absence of oxygen. One of the main products of anaerobic decomposition of organic matter in petroleum formation is kerogen (solid, insoluble organic matter present in sedimentary rocks).

2. Kerogen Formation

When organic sediments, mainly aquatic, are deposited for millions of years, many chemical reactions, microbial action and compaction occur at this burial stage. Through these processes, water is forced out while carbohydrates and proteins break down to form new waxy materials known as ‘kerogen’ and ‘bitumen’ (a black tar-like substance).

3. Catagenesis

Catagenesis or cracking now turns ‘kerogen’ into petroleum and natural gas Under increased pressure and temperature inside the burials, thermal degradation of kerogens begins to form hydrocarbon chains. This process is known as catagenesis.

Thus in this manner, under optimum conditions, petroleum is formed, whereas if conditions vary towards too high temperature, natural gas is formed. This crude oil and natural gas are then extracted by drilling wells into underground reservoirs.

Petroleum: Refining Process

Refining is the process of separating the various constituents of petroleum which is carried out in a petroleum refinery. The crude oil mixture is ‘fractionated’ or ‘separated’ into different components by fractional distillation.

Petroleum is refined by the process of ‘Fractional Distillation’, which is a distillation process based on the principle of difference in boiling points of miscible liquids present in petroleum. Let’s discuss this process:

1. Firstly, a tall fractionating column is fixed above the mixture (petroleum), with several condensers coming out of it at different heights. This column is hot at the bottom and cold at the top.
2. Substances with high boiling points condense at the bottom of the fractionating column itself, and substances with lower boiling points condense on the way as it rises to the top. Crude oil is a mixture of hydrocarbons. It is evaporated, and its vapours condense at various temperatures in the fractionating column.
3. This refined oil has impurities. So lastly, they are treated to obtain pure forms.

Petroleum Products: Types

Various types of petroleum products are:

Natural Gas: They are naturally occurring gas that contains mostly hydrocarbons. Gases like methane, hydrogen, fuel gas, ethane, propane, and butane are present in natural gas.

Diesel: It is commonly used as fuel in buses, trucks, locomotives, farms and heavy equipment. Diesel has greater energy and power density than gasoline.

Gasoline or Petrol: Gasoline is used in internal combustion engines, commonly used in private and commercial vehicles.

Kerosene: It is used widely in cooking and space heating. Kerosene is also the basic fuel for modern jet engines.

Fuel oil: It is also known as heavy oil, can be used as a source of power for lamps, heaters, stoves, engines, lanterns, etc., typically at home in furnaces and boilers. The machinery of farming, bunkering ships, etc., uses fuel oil.

Some other petroleum products include:

Naphtha is commonly used as solvents for paints, cosmetics, commercial dry cleaning etc.

Asphaltic bitumen is mostly used in the construction of roads and airfields and the manufacture of roofing felts, waterproof papers, electrical insulation, pipeline coatings, etc.

Carbon black – Decomposing liquid hydrocarbon fractions make carbon black which is mixed with rubber in tire manufacture and used in printing newspaper, coating in electrical wires, etc.

Petroleum: Uses

1. Transportation – Petroleum is a major source of energy for transportation. Most of the transportation fuels are obtained from petroleum. These fuels that are derived from petroleum include gasoline or petrol, diesel, liquefied petroleum gas (LPG), jet fuel, and marine fuel.
2. Power Generation – Petroleum or natural gas is used to generate electricity in power plants.
3. Chemical Industry – By steam cracking of natural gas, chemical plants produce olefins by liquids such as ethane and propane. These olefins are the basis for polymers used in making plastics, resins, fibres, lubricants, and gels.
4. Lubricants – Lubricants are a class of oils used to reduce the friction, heat, and wear between mechanical parts that are in contact with each other. This lubricating oil is used in motor vehicles.
5. Pharmaceuticals – In the health care sector, petroleum products are widely being used as plastics for medical supplies. Some processed plastics made with oil are used in making heart valves and other medical equipment. Petrochemicals are used to manufacture analgesics, antibiotics, antihistamines, cough syrups, lubricants, creams, ointments and gels.
6. Agriculture – One of the major uses of petroleum in agriculture is to produce ammonia which is used as a source of nitrogen for crops. Many types of machinery used in farms also use lubricants.
7. Other Domestic Uses – Petroleum is used for making many commodities that we use in our daily life such as cosmetic products, gels, etc.

Summary

Hence, we can conclude that petroleum products will continue to play a major role in our lives in future also. Though lots of research is going on to replace these petroleum products with renewable sources of energy, it is nearly impossible to stop using them. But while we use them in various aspects of our life like in transportation, industries, etc. we should not forget that they are fossil fuels and may end one day if not used wisely!

Petroleum Frequently Asked Questions

Frequently asked questions related to petroleum is listed as follows:

Q. What is petroleum?
A. Petroleum is a fossil fuel. It is a liquid that occurs naturally beneath the earth’s surface used as fuels after refining. Petroleum was formed by the decomposition of organic matter millions of years ago. They are essential natural resources for humanity.

Q. What are the three uses of petroleum?
A. The three main uses of petroleum are transportation, power generation and petrochemical industries.

Q. What is petroleum made of?
A. Petroleum products are fossil fuels made from crude oil and long chains of hydrocarbons present in natural gas. Coal, natural gas, and biomass are also responsible for the formation of petroleum.

Q. Is petroleum and crude oil the same?
A. Petroleum and crude oil are not the same but sometimes interchangeably. We know that crude oil is a mixture of hydrocarbons that exists as a liquid underground and remains a liquid when extracted. Petroleum is a broad category that includes both crude oil and petroleum products such as natural gas.

Q. Why is petroleum called black gold?
A. Petroleum is called ‘black gold’ because the crude oil which is extracted from the earth is black. But after its purification, this black crude oil gives golden colour. Also, petroleum is a costly fossil fuel, as gold is among the metals. Hence, due to its appearance and usefulness, it is known as black gold.

Now that you have a detailed article on Petroleum, we hope you do not face issues while preparing for the exam. Let us know in case of any difficulty in understanding the topic in the comments section below. We will get back to you at the earliest.