Common Atmospheric Pollutants and Their Sources

1. What is a major source of atmospheric pollutants?

Answer: Combustion of fuels.


2. Which three elements are in most fuels?

Answer: carbon, hydrogen and sulfur


3. What are particulates made from?

Answer: Solid particles and unburned hydrocarbons.


4. Which gas is colourless, odourless, toxic and results from the combustion of fuel?

Answer: carbon monoxide


5. What problems are caused by both sulfur dioxide and oxides of nitrogen?

Answer: respiratory problems and acid rain


6. What problems are caused by particulates?

Answer: Global dimming and health problems for humans.


7. Natural gas used to heat homes in the UK is mainly methane (CH4 ).

a) State the names of the elements in a molecule of methane.

Answer: carbon and hydrogen


b) State the number of atoms in one molecule of methane.

Answer: 5 (five)


c) Write the word equation for methane when completely combusted.

Answer: methane + oxygen  →  carbon dioxide + water


d) If there is a limited amount of oxygen when methane is combusted then different products form. State a pollutant that can be made from the incomplete combustion of methane and describe its effect on human health.

Answer: carbon monoxide which is toxic  or  carbon which causes breathing problems


8. Many fuels are hydrocarbons that are made from the fractional distillation of crude oil.

a) Write the symbol equation for the combustion of propane fuel (C3H8 ).

Answer: C3H8 + 5O2  →  3CO2 + 4H2O


b) Describe how carbon particulates can be produced by the combustion of fossil fuels and the effect on the environment.

Answer: During incomplete combustion/limited supply of oxygen solid particles and unburnt hydrocarbons can be released into the atmosphere. These can cause global dimming.


c) Explain how carbon monoxide can be produced by combustion of propane and the effect on the human body.

Answer: During incomplete combustion, carbon is not fully oxidised and carbon monoxide is formed. This gas reduces the oxygen carrying capacity of the blood (binds to red blood cells) and stops them from carrying oxygen and is toxic.


d) Burning of fuels is a major source of atmospheric pollutants. Explain how combustion of fossil fuels can lead to the formation of acid rain.

Answer: Fossil fuels can have some impurities of sulfur in them. When the fossil fuel combusts, the sulfur also combusts (oxidises) to form sulfur dioxide. During some combustion reactions, the nitrogen and oxygen in the air can be forced to react. The oxides of nitrogen and sulfur dioxide (sulfuric acid) dissolve into rain water and form acid rain.