Topic 9 - Chemistry of the atmosphere Flashcards
(32 cards)
What is the percentage of gases in our atmosphere?
Nitrogen - 80%
Oxygen - 20%
Small proportion of other gases, including carbon dioxide, water vapour and noble gases.
What happened in phase 1 in the evolution of the atmosphere in the 1st billion years?
In the first billion years intense volcanic activity released gases which formed the early atmosphere. Nitrogen was released by the volcanos and built up in the atmosphere. Water vapour was also released. But the atmosphere was mainly carbon dioxide. Little to no oxygen. We also think there were small amounts of methane and ammonia in the early atmosphere as well.
What happened in phase 2 in the evolution of the atmosphere in the 1st billion years?
Oceans, Algae and Green plants absorbed carbon dioxide. When the water vapour condensed it formed oceans. Lots of carbon dioxide was removed from the atmosphere as it was dissolved in the oceans and carbonates formed producing sediments. This reduced the amount of carbon dioxide in the atmosphere.
What happened in phase 3 of the evolution of the atmosphere?
Plants and algae produced oxygen by photosynthesis. Algae first started producing oxygen 2.7 billion years ago. Plants evolved over the next billion years and the plants produced even more oxygen. Eventually oxygen levels go so high that it was enough to support animals.
How did carbon dioxide decrease in the atmosphere?
The photosynthesis of algae and plants had also decreased the proportion of carbon dioxide in the atmosphere. It also decreased due to formation of sedimentary rocks and formation of fossil fuels.
Why do we need greenhouse gasses?
Important to have in atmosphere to support life as without them earth would be to cold.
What happens if there are too many greenhouse gases?
It can increase the temperature of the earth too much.
What are the three greenhouse gases we need to know?
Carbon dioxide
Methane
Water vapour
How does the greenhouse effect work?
Electromagnetic radiation is radiated out from the sun and passes through the earth’s atmosphere.
The earth absorbs most of this radiation warming it up.
The warmer the earth radiates a longer wavelength infrared radiation.
Some of the radiation goes back into space but some of the infrared radiation gets absorbed by the greenhouse gases in the atmosphere.
This increases the temperature of the atmosphere.
How do humans increase the amount of carbon dioxide in the atmosphere?
Carbon dioxide in the atmosphere is increased by; Vehicles and factories burning fossil fuels, deforestation.
How do humans increase the amount of methane in the atmosphere?
Methane in the atmosphere is increased by cattle farming and rice farming (paddy fields)
Are humans causing climate change?
Most scientists believe that human activities will cause the surface temperature of the earth to increase.
Define climate.
Climate refers to the average temperature and whether cycles over a long period of time.
Has the climate of earth been steady?
No, it has always been changing cycling through periods of extreme cold and warm. This used to be due to naturally occurring phenomenon for example volcanic eruption.
What is the difference between global warming and climate change?
Global warming refers to the warming of the climate due to human activities over the last 200 years.
Is there a correlation between the earths average temperature and the amount of carbon dioxide in the atmosphere?
Yes there is a strong correlation. Most scientists agree the extra carbon dioxide caused by humans is causing the increase in climate change.
Is an increase in global temperature a cause of climate change?
Yes it is a major cause of climate change.
What are some of the effects of global warming?
Glaciers melting
Droughts
Sea levels rising
Loss of habitats
Define a carbon footprint.
The total amount of carbon dioxide and other greenhouse gases emitted over the full lifetime of a product, event or service.
How can we reduce our carbon footprint and give some examples.
Reduce emissions of carbon dioxide and methane.
Example; Solar power, Cycle or walk instead of drive, Fly less, Plant trees.
Combustion of fuels is a major source of pollutants in the atmosphere. When fuels are combusted what is released?
Greenhouse gases and other pollutants such as carbon dioxide, sulfur dioxide etc.
How does complete combustion occur and what is the general word equation?
Complete combustion occurs when a hydrocarbon fuel is combusted in an excess of oxygen.
fuel + oxygen –> carbon dioxide + water
What is the advantages and disadvantages of complete combustion?
Advantages - Releases maximum amount of energy.
Disadvantages - Releases carbon dioxide and water
How does incomplete combustion occur and what is the general word equation?
Incomplete combustion occurs when a hydrocarbon fuel is combusted in a limited supply of oxygen. Incomplete combustion releases less energy and instead and produces carbon monoxide and/or particulate carbon.
Ethane + oxygen –> carbon monoxide + water
