When these fuels burn, the atoms in the fuels combine with oxygen from the air to make new molecules. Coal is made mainly of carbon. This burns to produce carbon dioxide. Petrol, diesel fuel and fuel oil are hydrocarbons.

When coal burns in air, carbon dioxide is formed.

When coal burns in air, it undergoes a chemical reaction known as combustion. Combustion is a process in which a substance reacts with oxygen to release energy in the form of heat and light. Coal is a fossil fuel that primarily consists of carbon.

Combustion of coal:
1. Coal is composed mainly of carbon, but it also contains small amounts of other elements such as sulfur, hydrogen, and oxygen.
2. When coal is heated and exposed to air (which contains oxygen), the carbon in coal reacts with the oxygen in the air to produce carbon dioxide (CO2) gas.
3. The balanced chemical equation for the combustion of carbon can be represented as follows:
C + O2 → CO2

Formation of carbon dioxide:
During the combustion process, the carbon atoms in coal combine with oxygen molecules from the air to form carbon dioxide. This reaction occurs due to the high temperature and the presence of oxygen.

Importance of carbon dioxide formation:
Carbon dioxide is a greenhouse gas that plays a significant role in the Earth's climate system. It traps heat from the sun and prevents it from escaping back into space, leading to the greenhouse effect. While carbon dioxide is a natural component of the Earth's atmosphere, the burning of fossil fuels, including coal, has significantly increased its concentration, contributing to global warming and climate change.

Other byproducts of coal combustion:
While carbon dioxide is the primary byproduct of coal combustion, other gases and substances can also be formed depending on the composition of the coal and the combustion conditions. Some of these byproducts include:

- Sulfur dioxide (SO2): If the coal contains sulfur impurities, they will react with oxygen during combustion to form sulfur dioxide. This gas contributes to air pollution and can cause respiratory issues and environmental damage.
- Carbon monoxide (CO): In incomplete combustion, where there is a limited supply of oxygen, carbon monoxide can be formed instead of carbon dioxide. Carbon monoxide is a poisonous gas that can be harmful to human health.
- Hydrogen gas (H2): While coal itself does not contain hydrogen, some hydrogen gas may be released as a byproduct of coal gasification or during the combustion of certain types of coal.

Conclusion:
When coal burns in air, the primary byproduct is carbon dioxide. This gas is a major contributor to climate change and is formed due to the reaction between carbon in coal and oxygen in the air. However, it is important to note that coal combustion can also produce other gases such as sulfur dioxide, carbon monoxide, and hydrogen gas depending on various factors.

Carbon dioxide