C9 - Chemistry of the Atmosphere Flashcards
What is the composition of gases in the Earth’s current atmosphere?
- Nitrogen: 78%
- Oxygen: 21%
- Other gases: 1%
How did early, intense volcanic activity help form the early atmosphere?
- large amount of CO2 released
- little/ no oxygen released
- small amounts of other gases (ammonia and methane) released
- Nitrogen also released –> gradually built up in atmosphere as it’s unreactive.
How did the oceans form?
- Water vapour released
- Condensed as Earth cooled
- Formed oceans
Why did levels of carbon dioxide in the atmosphere change as oceans formed?
- CO2 is a soluble gas
- It dissolves in water
- As oceans formed –> CO2 dissolved to form soluble carbonate compounds
- Amount of CO2 in atmosphere decreased. -
- Carbonate compounds then precipitated as sedimentary rocks (like limestone)
State the approximate time in Earth’s history when algae started producing oxygen?
- Algae first evolved around 2.7 billion years ago
- Soon after oxygen began to exist in the atmosphere.
Describe the effects of a gradually increasing oxygen level.
- O2 increased due to photosynthesis
- O2 gradually built up in the atmosphere.
- Eventually, the amount of oxygen present in the atmosphere enabled animals to evolve.
Explain the ways that atmospheric carbon dioxide levels decreased.
- Algae and plants decreased the % CO2 in the atmosphere by photosynthesis
- Formation of sedimentary rocks that contain carbon
- Production of fossil fuels from remains of dead plants and animals when they decay
- Oceans absorbed CO2
Name some greenhouse gases.
- Water vapour
- Carbon dioxide
- Methane
- Nitrous oxide
Describe briefly how the greenhouse gases cause an increase in Earth’s temperature.
- Gases absorb heat radiated from Earth
- Release energy in all directions
- Keeps Earth warm
Describe the greenhouse effect.
- Electromagnetic radiation at most wavelengths passes through Earth’s atmosphere.
- Earth absorbs most of the radiation and warms up.
- Earth radiates energy as infrared radiation.
- Some of the infrared radiation goes into space.
- Some of the infrared radiation is absorbed by greenhouse gases in the atmosphere.
- Lower atmosphere warms up.
What are some human activities that produce greenhouse gases?
- Farming cattle releases methane
- Farming rice in paddy fields releases methane
- Burning fossil fuels releases carbon dioxide
- Deforestation releases carbon dioxide and reduces absorption of carbon dioxide through photosynthesis
Why might some believe that humans are not the cause of climate change?
- Rise in global temperatures is caused by natural factors and cycles of climate change.
- Climate science is complicated and it is difficult to predict and explain what will happen to global temperatures in the future
- Media may present opinions and articles which are simplified/inaccurate/biased
What is the difference between global warming and climate change?
- Climate change: the long-term alterations of weather patterns
- Global warming: rise in average temperature of Earth’s surface
What are some side effects of global warming?
- Glaciers and polar ice melting
- Sea levels rising
- Patterns of rainfall changing –> leads to floods or droughts
- habitats changing
Define ‘carbon footprint’.
The carbon footprint of a product is:
- total amount of CO2 (and other greenhouse gases)
- which are emitted over the full life cycle
