Topic 9 - Chemistry of the Atmosphere

Question 1

What is the proportion of the gases in the atmosphere today?

Answer 1

— 79% nitrogen
— 20% oxygen
— 1% other gases including water vapour, carbon dioxide and noble gases

Question 2

Explain the Earth’s early atmosphere in as much detail possible.

Answer 2

— Volcanic eruptions released lots of nitrogen’s which built up in the atmosphere as well as water vapour, methane and ammonia
— When water vapour condensed, it formed oceans.
— Carbon dioxide dissolved in the oceans which went through a series of reactions to form carbonate precipitates and formed sediments on the seabed.
— Carbon dioxide was also taken in by plants for photosynthesis
— Carbon became locked up in rocks and fossil fuels when organisms died.
— Oxygen is released by photosynthesis of plants

Question 3

Compare the earth’s early atmosphere and the atmosphere today.

Answer 3

The early atmosphere was mostly carbon dioxide with no oxygen whereas todays atmosphere is mostly nitrogen. The earths early atmosphere is like the atmosphere of Mars and Venus today.

Question 4

Why is evidence of the earth’s early atmosphere limited?

Answer 4

The atmosphere was formed 4.6 billion years therefore there have been many theories about the atmosphere and how it has changed.

Question 5

Describe the greenhouse effect in terms of short and long wavelength.

Answer 5

Carbon dioxide, water vapour and methane particles absorb certain frequencies of radiation. These greenhouse gases don’t absorb the short wavelengths but they absorb the long wavelengths -thermal radiation- which reflect back off the Earth and re-radiate in all directions. This is the greenhouse effect.

Question 6

What human activities contribute to the levels of carbon dioxide and methane?

Answer 6

— Deforestation adds carbon dioxide to the atmosphere
— Burning of fossil fuels adds carbon dioxide into the atmosphere as the carbon that was locked is released
— Agriculture adds methane as the farm animals produce methane through their digestive processes
— Creating waste adds methane as there are more landfill sites therefore methane is released by decomposition

Question 7

What problems can particulates in the air cause?

Answer 7

• – When inhaled, particulates can get stuck in the lungs leading to respiratory issues
• – Global dimming as they reflect sunlight back into space

Question 8

What problems does carbon monoxide cause?

Answer 8

• – Can bind to the haemoglobin in the blood which means less oxygen can bind to the haemoglobin to be transported around the body
• – Carbon monoxide has no smell or colour so it is hard to detect which makes it even more dangerous