P2 - Chemistry of the Atmosphere (Done) Flashcards
How many phases were there in the evolution of the atmosphere ?
Three phases.
What happened in phase one of the atmosphere ?
Volcanoes in earths early life erupted and released gases forming the early atmosphere. Consisting primarily of carbon dioxide with little oxygen - similar to mars’ and venus’ atmospheres today. They also released nitrogen, water vapour and a little methane and ammonia. Oceans formed when water vapour condensed.
What happened in phase two of the atmosphere ?
Over time carbon dioxide was removed from the atmosphere, lots dissolving into the oceans forming carbonates that precipitated as small, solid particles. When green plants and algae evolved, they took in some during photosynthesis.
What happened in phase three of the atmosphere ?
Algae evolved 2.7 billion years ago, and green plants over the next billion years, and they produced oxygen though photosynthesis. Over time oxygen levels built up allowing animals to evolve.
What are the proportions of the gases in today’s atmosphere ?
They have been similar for the past 200 million years: 80% nitrogen, 20% oxygen, and small amounts of other gases (<1%) including carbon dioxide, noble gases and water vapour.
What are greenhouse gases ?
Carbon dioxide, methane and water vapour - they keep the earth warm enough to support life.
How do greenhouse gases work ?
1 - the sun gives out short wave radiation, 2 - reflected back by the earth as long wave(thermal) which is absorbed by greenhouse gases, 3 - they then give this out in all directions, 4 - some back to earth warming the surface.
What human activities increase the amount of greenhouse gases ?
Deforestation - less photosynthesis, agriculture - farm animals produce methane, creating waste - carbon/methane released when it breaks down, and burning fossil fuels - carbon that was ‘locked up’ in these fuels is released as CO2.
How is increased carbon dioxide linked to climate change ?
Extra carbon dioxide from human activity causes greenhouse layer to increase, heating up the earth.
What could some consequences of climate change be ?
Higher global temperatures - ice in Arctic and Antarctic could melt leading to rising sea levels, change in rainfall leading to abnormal levels of precipitation and storms becoming more frequent and severe.
What is a carbon footprint ?
A measure of the amount carbon dioxide and other greenhouse gases released over the full life cycle of something.
How can you reduce the carbon footprint of something ?
By reducing the amount of greenhouse gases given out by a process: using renewable energy sources or nuclear energy, using more efficient industrial processes, put limits on greenhouse gas output for companies and develop technology that catches carbon dioxide and traps it under ground.
Why is reducing carbon footprint difficult ?
There’s still a lot of work to be done on alternative technologies to reduce CO2 emissions (carbon capture and storage), and many renewable technologies are still quite expensive (solar panels).
Why are some governments reluctant to to make changes to reduce CO2 emissions ?
They’re worried it could have an impact on their economic growth - which could be bad for peoples well-being especially for still developing countries.
Why is it hard to make international agreements to reduce emissions ?
Not everyone’s on board and most countries don’t want to sacrifice their economic development if others won’t too.
How can individuals reduce their own carbon footprint ?
They can cycle or walk instead of using a car, reduce their air travel and doing activities to save energy - turning the lights off more.
How did carbon become trapped in fossil fuels or rocks ?
When plants/plankton/marine animals dies they fell to the seabed and got buried by sediment, over millions of years they were compressed to form sedimentary rocks, oils and gas - trapping the carbon in fossil fuels.
What is coal ?
It’s a sedimentary rock made from thick plant deposits.
What are crude oils and natural gases ?
Formed from deposits of plankton - they form reservoirs under the seabed when they get trapped in rocks.
What is limestone ?
A sedimentary rock made of mostly calcium carbonate deposits from shells and skeletons or marine organisms.
What are hydrocarbons ?
Compounds that only contain hydrogen and carbon.
What happens during combustion of fossil fuels ?
The carbon and hydrogen in the hydrocarbons are oxidised releasing carbon dioxide and water vapour into the atmosphere.
What is complete combustion ?
When there’s enough oxygen present - all of the fuel burns.
What is incomplete combustion ?
When there’s not enough oxygen - some of the fuel doesn’t burn releasing particulates made up of soot (carbon) and unburned hydrocarbons, and carbon monoxide can be produced as well as carbon dioxide.
