Organic Chemistry - Fuels

This section covers the three main fossil fuels: coal, natural gas, and petroleum. We will learn to identify and describe their properties and uses.

Coal

Coal is a dark-colored, solid fossil fuel formed from the remains of ancient plants that lived in swampy environments millions of years ago. It is a sedimentary rock.

Formation

Coal forms over millions of years through a process of compaction and heating of plant matter under high pressure and temperature.

Types of Coal

Coal is classified into different ranks based on its carbon content and heat value:

• Lignite: The lowest rank of coal. It has a low carbon content and a high moisture content.
• Bituminous: The most common type of coal. It has a medium carbon content and is used for power generation.
• Anthracite: The highest rank of coal. It has a high carbon content and burns with little smoke.

Uses of Coal

1. Power Generation: Coal is burned to heat water and produce steam, which drives turbines to generate electricity.
2. Iron and Steel Production: Coal is used as a reducing agent in the production of iron and steel.
3. Heating: Historically, coal was widely used for heating homes.

Natural Gas

Natural gas is a colorless, odorless gas primarily composed of methane ($CH_4$). It is found underground, often alongside coal and petroleum deposits.

Formation

Natural gas forms when organic matter is buried under high pressure and temperature for millions of years. The organic matter breaks down into hydrocarbons, including methane.

Composition

Besides methane, natural gas can also contain other hydrocarbons like ethane, propane, and butane, as well as non-hydrocarbon gases like carbon dioxide and nitrogen.

Uses of Natural Gas

• Power Generation: Natural gas is burned to generate electricity.
• Heating: It is used for heating homes and water.
• Cooking: Natural gas is a common fuel for cooking stoves and ovens.
• Industrial Processes: It is used as a fuel in various industrial processes.

Petroleum

Petroleum, also known as crude oil, is a liquid fossil fuel composed of a mixture of hydrocarbons. It is found underground in porous rock formations.

Formation

Petroleum forms from the remains of microscopic marine organisms (plankton and algae) that accumulate on the ocean floor. These organisms are buried under layers of sediment, which compacts them and heats them over millions of years, transforming them into hydrocarbons.

Composition

Petroleum is a complex mixture of hydrocarbons with varying chain lengths. These hydrocarbons are separated into different fractions through fractional distillation.

Fractions of Petroleum (obtained by fractional distillation):

Fraction	Boiling Point (°C)	Uses
Gases	-160 to -40	LPG (Liquefied Petroleum Gas), petrol gas
Petrol (Gasoline)	40 to 200	Fuel for cars
Naphtha	70 to 200	Petrochemicals (plastics)
Diesel Oil	200 to 300	Fuel for diesel engines (trucks, buses)
Fuel Oil	300 to 370	Heating oil for ships and power stations
Bitumen	370°C and above	Road surfacing

Uses of Petroleum

• Transportation: Petrol and diesel are the primary fuels for cars, trucks, and other vehicles.
• Petrochemicals: Petroleum is a raw material for the production of plastics, synthetic rubber, and other chemicals.
• Heating and Power Generation: Fuel oil and gas oil are used for heating and power generation.