Chemistry unit 9 Flashcards
What is the modern composition of elements in our atmosphere
78% Nitrogen, 21% Oxygen, 1% argon, 0.04% CO2, very little water vapour
How is this different to the earths atmosphere 4.6 billion years ago
Back then, there was a lot more CO2 in the air and no oxygen as there was no photosynthesis. There were also larger traces of Methane and phosphorus
Explain how earths atmosphere has changed over time
The earth began very hot due to frequent volcanic eruptions that put CO2 and Nitrogen into the atmosphere. As it cooled down, Water vapour condensed and it rained for a long time to form Oceans. These Oceans dissolved CO2 into the water and produced sediments, which decreased CO2 levels in the atmosphere.
How did oxygen levels increase
Life began to form as plants and algae and they could photosynthesise so they took in CO2 and released oxygen so over time, more and more oxygen replaced the CO2. These higher oxygen levels meant that other animals could start to grow.
6CO2 + 6H2O → C6H12O6 + 6O2 + 6H2O
How else did CO2 levels decrease
-Sedimentary rocks formed as carbon which trapped the gas away for billions of years until we started burning it for fuel today,
-Algae and plants decreased it
What is the (normal) greenhouse effect
Em Radiation enters the earths atmosphere and heats the planet up when the earth absorbs some of it. When the remaining radiation try’s escaping the atmosphere, greenhouse gases such as water vapour block it and keep it in which helps to keep the planet warm so life can exist
What is the enhanced greenhouse effect
Due to human activity of burning fossil fuels, there has been an increased number of these greenhouse gases entering the atmosphere and so more heat is trapped inside the atmosphere but it is more than the planet can handle so global warming takes place
Give some examples of human activity in burning fossil fuels
-Driving
-Consuming electricity
-Landfill site decay
-Animal Farming (cattle produce methane)
What are some of the effects of global warming
Extinction of species, rising sea levels, Ocean acidification, migration due to floods and droughts
What is a carbon footprint and how can we decrease ours
The total amount of CO2 emitted in the lifecycle of a product.
We can decrease carbon footprints by using less electricity or making sure we buy locally sourced foods to reduce travel miles
How are atmospheric pollutants like soot produced from burning fossil fuels
often incomplete combustion takes place and so instead of CO2 beings formed, CO or just C are formed and they are for the environment because carbon monoxide is toxic and carbon soot can cause global dimming. other substances like sulphur dioxide may be trapped in the fossil fuels
name some atmospheric pollutants
Carbon monoxide, sulphur dioxide, particulates
What are the properties and effects of these pollutants
-Carbon monoxide is a colourless toxic gas so not easily detected.
-Sulphur dioxide can cause reparatory problems and acid rain.
-Particulates cause global dimming and health problems
Why cant we always trust what the media say about global warming
it is a very complicated process that we cannot describe in a simple way to the public
