3.2 - Petroleum

Petroleum is a natural liquid found beneath the Earth’s surface, primarily consisting of hydrocarbons (compounds made up of hydrogen and carbon atoms). It is an essential source of energy and is used for a variety of purposes, including fuel for vehicles, heating, and in the production of numerous chemical products like plastics, fertilizers, and pharmaceuticals.

Formation of Petroleum

Petroleum is formed from the remains of tiny plants and animals that lived millions of years ago. These organisms got buried under layers of mud and sand. Over time, with heat and pressure, the organic material broke down and transformed into petroleum. This process can take millions of years.

Composition of Petroleum

The main components of petroleum are hydrocarbons, which can be divided into:

• Alkanes: Saturated hydrocarbons with only single bonds between carbon atoms, e.g., methane (CH₄).
• Alkenes: Unsaturated hydrocarbons containing one or more double bonds between carbon atoms.
• Aromatic hydrocarbons: Compounds containing rings of carbon atoms, such as benzene (C₆H₆).

Extraction of Petroleum

Petroleum is extracted through drilling. Special oil rigs are used to drill deep into the Earth’s crust to reach the petroleum deposits. The extracted crude oil is then transported to refineries for further processing.

Refining of Petroleum

Once crude oil is extracted, it undergoes a process called refining. This involves separating the different components of the oil based on their boiling points. This process is known as fractional distillation. The crude oil is heated in a distillation column where it vaporizes. The vapor rises up through the column, and different components condense at different heights due to their varying boiling points. Some of the main fractions obtained include:

• Petrol (gasoline)
• Diesel
• Kerosene
• Liquefied Petroleum Gas (LPG)
• Bitumen

Uses of Petroleum

Petroleum and its products are used in a wide range of applications. Some of the important uses include:

• Fuel: Petroleum products like petrol and diesel are used in vehicles, airplanes, and other forms of transportation.
• Heating: Kerosene and natural gas are used for heating purposes.
• Electricity Generation: In some cases, petroleum is used in power plants to generate electricity.
• Petrochemicals: Petroleum is a raw material for the production of chemicals, plastics, synthetic rubber, and fertilizers.

Environmental Impact

The extraction and use of petroleum have significant environmental impacts. Some of the major concerns include:

• Pollution: The burning of petroleum products releases harmful gases like carbon dioxide (CO₂) and carbon monoxide (CO), contributing to air pollution and global warming.
• Oil Spills: Accidental leaks and spills during transportation or drilling can cause damage to marine ecosystems and wildlife.
• Resource Depletion: Petroleum is a non-renewable resource, meaning it will eventually be exhausted if not managed sustainably.

Formula for Combustion of Hydrocarbons

The combustion of hydrocarbons, such as methane (CH₄), is a chemical reaction where the hydrocarbon reacts with oxygen (O₂) to produce carbon dioxide (CO₂) and water (H₂O), along with the release of energy:

$CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O + \text{Energy}$

This exothermic reaction is the basis for the use of petroleum products as fuels.