• about four-fifths (approximately 80%) nitrogen • about one-fifth (approximately 20%) oxygen • small proportions of various other gases, including carbon dioxide, water vapour and noble gases.
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What is the theory from the first billion years? (Volcanoes)
One theory suggests that during the first billion years of the Earth’s existence there was intense volcanic activity that released gases that formed the early atmosphere.
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What had then happen to water vapour? (THEN)
Water vapour that condensed to form the oceans.
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What was the atmosphere like (CO2; etc.)?
At the start of this period the Earth’s atmosphere may have been like the atmospheres of Mars and Venus today, consisting of mainly carbon dioxide with little or no oxygen gas.
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What do volcanoes produce? (Chemically)
Volcanoes also produced nitrogen which gradually built up in the atmosphere and there may have been small proportions of methane and ammonia.
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What happened when the oceans formed CO2?
When the oceans formed carbon dioxide dissolved in the water and carbonates were precipitated producing sediments.
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What does this then cause? (Question 6)
This then reduces the amount of carbon dioxide.
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How else is CO2 decreased?
The formation of sedimentary rocks and fossil fuels that contain carbon.
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What did Algae and Plants decrease?
They decreased the percentage of carbon dioxide in the atmosphere by photosynthesis.
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What have algae and plants produced?
Produced the oxygen that's now in the atmosphere by photosynthesis.
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When did algae first produce oxygen?
2.7 billion years ago and soon after this oxygen it was in the atmosphere.
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What is the photosynthesis equation?
6CO2 + 6H2O -> C6H12O6 +6O2.
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How do greenhouse gases help?
Maintained temperatures on Earth high enough to support life.
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Give an example of greenhouse gases.
Water vapour, carbon dioxide and methane.
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What greenhouse gases increase in amount due to human activities?
• carbon dioxide • methane
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What is a carbon footprint?
The carbon footprint is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.
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How is the carbon footprint reduced?
Reducing emissions of carbon dioxide and methane.
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What is the combustion of fuels?
Big source of atmospheric pollutants.
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What do many fuels contain?
Coal and other fuels contain carbon/hydrogen and some sulfur.
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What are the gases releasing when burning fuels?
Carbon dioxide, water vapour, carbon monoxide, sulfur dioxide and oxides of nitrogen.
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What is carbon monoxide?
A toxic gas that's colourless and odourless.
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How is sulfur dioxide dangerous?
Causes respiratory problems in humans and cause acid rain.
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What do particulates cause?
Global dimming and health problems for humans.
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Other cards in this set
Card 2
Front
What is the theory from the first billion years? (Volcanoes)
Back
One theory suggests that during the first billion years of the Earth’s existence there was intense volcanic activity that released gases that formed the early atmosphere.
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