Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
7 Cards in this Set
- Front
- Back
|
Describe the Earth's early atmosphere?
|
The earth's surface was originally molten. Any atmosphere boiled away due to the extreme heat. Things started to cool and thin crusts formed and volcanoes started erupting. The volcanoes gave off CO2, water vapour, and small amounts of other gases. The water vapour condensed and formed the oceans. It was mostly CO2 with almost no oxygen.
|
|
|
Describe phase 2 of the evolution of the earth's atmosphere?
|
A lot of early CO2 dissolved into the oceans. Green plants evolved over most of the earth. They removed CO2 from the atmosphere and produced oxygen through photosynthesis. This caused the oxygen levels to gradually increase.
|
|
|
Describe phase 3 of the evolution of the earth's atmosphere?
|
The build up of oxygen killed off some early organisms but allowed others to evolve. The oxygen also created the ozone layer which blocked harmful rays from the sun and enabled more organisms to evolve.
|
|
|
Describe today's atmosphere?
|
78% nitrogen
21% oxygen Small amounts of gases |
|
|
Explain the experiment you can do to investigate the proportion of oxygen in the atmosphere?
|
When its heated, copper reacts with oxygen in the air to make copper oxide, so it uses up oxygen. If you heat an excess of copper in a tube and pass air over it using two syringes, you can tell how much oxygen has been used up by reading the markers on the syringes. So if you start off with 100cm3 of air, you should end up with 80cm3 when the reaction is finished. The equation for this reaction is 2Cu + O2 = 2CuO.
|
|
|
Explain how human activity is changing the atmosphere?
|
Burning fossil fuels- releases CO2 into atmosphere
Deforestation- Trees take in CO2 so getting rid of them will leave more CO2 in the atmosphere Livestock farming- releases a lot of methane (cH4) into atmosphere. |
|
|
Explain how volcanic activity is changing the atmosphere?
|
Sulfur dioxide is thrown up into atmosphere when volcanoes erupt which reacts with sunlight, water, oxygen and dust to form volcanic smog. Carbon dioxide is also released in this way.
|
