Chemistry of the Atmosphere (review)

1. Theories about how the atmosphere was formed have changed and developed over time.

a) Put the statements below in order so that they describe the main stages of atmospheric formation in one theory.

Answer: The order is C – D – B – E – A

b) State the name of the process that made oxygen in the Earth’s atmosphere.

Answer: photosynthesis

c) Carbon dioxide is a greenhouse gas. Define the term "greenhouse gas".

Answer: A gas that absorbs longwave infrared radiation reflected by the Earth. This maintains the temperature high enough on Earth to support life as we know it.

d) Give some ways in which humans have increased the amount of carbon dioxide gas in our atmosphere.

Answer: burning fossil fuels and deforestation

2. Coal, oil and natural gas are all examples of fossil fuels. These resources are widely used in industry as well as our homes for energy, heating and electricity production.

a) Describe how acid rain can form due to combustion of coal.

Answer: Coal contains sulfur impurities. When coal is used and combusted, the sulfur will also burn. Oxides of sulfur are acidic and combine with natural rain water to make acid rain.

b) Explain how carbon monoxide can be formed from the combustion of fossil fuels. Describe the health problems that it can cause.

Answer: Fossil fuels are made of mainly hydrocarbons. When they are used, they are combusted. If oxygen is limited, then incomplete combustion happens which produces carbon monoxide. Carbon monoxide is a colourless, odourless toxic gas. Carbon monoxide attaches to the haemoglobin (red blood cells) and reduces their ability to carry oxygen around the body. This causes headaches, confusion and can cause death.

c) Justify the importance of having some carbon dioxide in our atmosphere.

Answer: Carbon dioxide is needed by plants for photosynthesis. Without this there would be no oxygen made in our atmosphere and life that needs oxygen from the air would die out. Carbon dioxide is a greenhouse gas. This means that it traps longer wave radiation reflected from the Earth. This natural process keeps the temperatures at a level to support life.

d) Explain carbon neutral fuels could reduce carbon footprints.

Answer: Carbon neutral fuels have a zeronet release of greenhouse gases into the atmosphere. This would reduce the carbon footprint of many products and services as fuels are essential for producing goods and services.

3. Peer-reviewed scientific research indicates that humans are adding more greenhouse gases to the atmosphere and this is likely to be the main cause of climate change.

a) Explain the importance of peer-reviewed scientific research.

Answer: Peer-reviewing means that the research is likely to be unbiased. The research is likely to be of a high standard and can be trusted.

b) Suggest why almost all scientists now agree that humans are contributing to global warming, but some people do not think that global warming is due to human activity and that climate change will continue. Suggest why this is.

Answer: Models that predict the climate are simplified. Leading to a level of uncertainty of future global temperatures.

c) Describe the potential effects of global climate change.

Answer: As temperatures rise, the polar ice caps will melt, and this will cause the sea level to rise. Low lying areas will be flooded and coastal erosion will be increased. More extreme weather events like drought and storms will increase in frequency. The amount, timing and frequency of rainfall affected with some areas of the world getting more rain and some less. The availability of fresh water is likely to reduce as droughts occur. These changes will affect habitats and wildlife as well as the types of crops that can be grown in different parts of the world.

d) Suggest ways to reduce global climate change.

Answer: Global climate change can be reduced by reducing emissions of greenhouse gases (carbon dioxide and methane), carbon capture and storage, carbon neutral fuels.