Topic 1 - Earth's Sea And Atmosphere Flashcards
What gases were in the early atmosphere?
Mostly CO2.
Small amounts of water vapour (H20), ammonia (NH3) and methane (CH4).
Where did the gases come from that formed the atmosphere?
The earths surface was originally molten for many millions of years. It was so hot that any atmosphere just killed away into space. Eventually things cooled down and a thin crust formed but volcanoes continued to erupt. The volcanoes gave out lots of gases which most likely formed the early Atmosphere.
Why don’t we know exactly how the atmosphere formed?
- long time ago so we don’t have much evidence and no one was there at the time.
- learnt a lot from Antarctic ice cores. Each year, a layer of ice forms and bubbles of air get trapped inside it, then it’s buried by the next layer. So the deeper the ice, the older the air.
Why and Where did the water come from to form the oceans?
All the water vapour in the atmosphere condensed to form the oceans, when the earth cooled.
How did the growth of plants affect the early atmosphere?
Due to photosynthesis it:
- increased 02 (waste product)
- decreased CO2
Why did the amount of CO2 in the atmosphere fall? Give 4 reasons.
- it dissolved in the oceans
- green plants used it up in Photosynthesis
- used in production of sedimentary rocks
- used in production of fossil fuels
How much of the air today is oxygen?
21%
How could you measure the proportion of oxygen in air? (Copper method)
1) When it’s heated, copper oxide reacts with oxygen in the air to make copper oxide, so the reaction uses up oxygen.
2) If you heat an excess of copper in a tube and pass air over it using two syringes, you can use the markers on the syringes to tell how much oxygen has been used.
How could you measure the proportion of oxygen in air? (Candle method)
Weigh a candle, light it and immediately put it inside a very large, sealed container. The candle will stop burning when there is no oxygen left inside the container. Wait for candle to stop burning, weigh it again. The candle will be lighter because some reacted with oxygen to burn. If we know the size of the container, we can calculate how much oxygen there is for a particular volume of air.
What gases are in the atmosphere today?
Nitrogen - 78%
Oxygen - 21%
Argon - 0.9%
Carbon dioxide - 0.037%
How do volcanoes affect the current atmosphere?
Sulphur dioxide - can be thrown high into the atmosphere when volcanoes erupt. It reacts with sunlight, water, oxygen and dust to form volcanic smog. It also causes acid rain.
Carbon dioxide - released into atmosphere by volcanic eruptions which causes warming adding to the greenhouse effect.
How do humans affect the current atmosphere?
Deforestation - increases CO2 levels as trees take CO2 from atmosphere.
Burning fossil fuels - releases CO2, raises levels of greenhouse gases, traps infrared heat, warming atmosphere above normal temperature (global warming.)
Farming - releases huge amount of methane (CH4) due to cattle. Plants absorb CO2 and produce O2 so by picking them you -O2 and +CO2. Produce is shipped all over world, releasing CO2.
