The composition of the atmosphere changes when fossil fuels are burned in air - Edexcel - GCSE Chemistry - Question 6 - 2012 - Paper 1

The incomplete combustion of methane results in the formation of carbon soot and carbon monoxide, which pose several problems:

1. Soot Production: Carbon soot can accumulate on surfaces, leading to increased air pollution and respiratory issues in humans and animals due to inhalation of fine particulate matter.

2. Toxicity of Carbon Monoxide: Carbon monoxide is a toxic gas that can bind with hemoglobin in red blood cells, reducing the blood's ability to carry oxygen. This can lead to severe health consequences, including headaches, confusion, and in extreme cases, death.

3. Environmental Impact: Both soot and carbon monoxide contribute to poor air quality, which can harm the environment and contribute to climate change.

Impurities in fossil fuels, particularly sulfur compounds, play a significant role in the formation of acid rain:

1. Combustion of Fossil Fuels: When fossil fuels are burned in air, sulfur impurities react with oxygen to form sulfur dioxide.

2. Formation of Acidic Compounds: Sulfur dioxide can further react with water vapor in the atmosphere, leading to the formation of sulfuric acid. This process can be summarized as:

   $$$$

ightarrow ext{H}_2 ext{SO}_4$$

3. Acid Rain Precipitation: The sulfuric acid dissolves in rainwater, resulting in acid rain, which can have harmful effects on aquatic ecosystems, vegetation, and buildings.