Pollutants

Question 1

Describe the process of incomplete combustion.

Answer 1

• Combustion reactions of hydrocarbons in the presence of little oxygen
• The products contain less oxygen than carbon dioxide, so carbon monoxide and carbon in the form of soot are produced, as well as carbon dioxide and water

Question 2

Explain why carbon monoxide is harmful.

Answer 2

• Carbon monoxide can bind to haemoglobin in red blood cells
• This prevents oxygen from being carried around the body

Question 3

Describe the problems associated with soot as a product of incomplete combustion.

Answer 3

• During incomplete combustion, tiny particles of carbon are released into the atmosphere and fall to form soot
• It makes buildings look dirty, reduces air quality and can cause respiratory problems

Question 4

Explain how sulfur dioxide is formed and how it causes acid rain.

Answer 4

• Alongside other harmful gases, sulfur dioxide is released when fossil fuels are burned due to sulfur impurities within them
• When sulfur dioxide mixes with clouds, it forms dilute sulfuric acid which falls as acid rain

Question 5

Give some harmful effects of acid rain.

Answer 5

• It causes lakes to become acidic and many plants and animals die as a result
• It kills trees and damages limestone buildings and stone statues, can also make metal corrode

Question 6

Explain how nitrogen oxides are formed.

Answer 6

• Created from a reaction between nitrogen and oxygen in the air
• This is caused by energy released by combustion reactions in the internal combustion engines of cars

Question 7

Describe the harmful effects of nitrogen oxides as a pollutant.

Answer 7

• They contribute to acid rain and cause photochemical smog at ground level
• Photochemical smog is a type of air pollution that causes breathing difficulties

Question 8

Give the advantages to using hydrogen gas as a fuel.

Answer 8

• It is a very clean fuel
• In hydrogen fuel cell, hydrogen combines with oxygen to release energy, and the only waste product is water
• Hydrogen is obtained from that water which is a renewable resource

Question 9

Give the disadvantages to using hydrogen gas as a fuel.

Answer 9

• Special, expensive engines required to produce it
• Expensive and uses energy from another source to manufacture it, which often comes from burning fossil fuels
• It is hard to store and not widely available