C1 Topic 1 - The Earth's Sea and Atmosphere Flashcards
Describe phase 1 of the early atmosphere.
The Earth’s surface was molten but cooled down and a thin crust formed but volcanoes kept erupting. The volcanoes gave out carbon dioxide, water vapour and small amounts if other gases. The oceans formed when the water vapour condensed.
Describe phase 2 of the early atmosphere.
A lot of the early carbon dioxide dissolved into the oceans. Later marine organisms developed which took in some of the carbon dioxide. When they died the organisms were buried under layers of sediment. Green plants removed carbon dioxide from the atmosphere and produced oxygen by photosynthesis. The oxygen level gradually increased.
Describe phase 3 of the early atmosphere.
The build-up of oxygen killed off some organisms that couldn’t tolerate it but allowed other, more complex organisms to evolve and flourish. The oxygen created the ozone layer which blocked harmful rays from the sun which allowed even more complex animals to evolve. There’s little carbon dioxide left now.
Why is it difficult to predict what the early atmosphere was made up of?
No one was around to observe the atmosphere and there was no written evidence.
What are the gases in the atmosphere today?
78% Nitrogen, 21% Oxygen, nearly 1% of Argon and 0.04% Carbon dioxide.
Describe a test for how to determine how much oxygen is in the air.
Heat copper in a tube and pass air over it using syringes. The copper reacts with oxygen in the air to make copper(II) oxide. The markets will show how much oxygen has been used up.
Explain how small changes in the atmosphere occur due to volcanic and human activities.
Burning fossil fuels release carbon dioxide by being burnt in power stations and in car engines. Deforestation causes a load of carbon dioxide to be left in the atmosphere. Livestock farming releases huge amounts of methane into the atmosphere by animals passing wind. Sulphur dioxide can be thrown high into the atmosphere which reacts with sunlight, water, oxygen and dust to form volcanic smog. Carbon dioxide is also released by volcanic eruptions.
