C9-chemistry of the atmosphere

What happened in phase 1?

-the surface of the earth was covered with volcanos that erupted and released lots of gases (how the early atmosphere was formed)

P1 What was the early atmosphere like?

-Mostly CO2, with virtually no oxygen

-similar to the atmosphere of Venus & Mars today

P1 What did the volcanic activity release?

-nitrogen

-water vapour

-small amounts of methane+ammonia

-built in the atmosphere over time

what happened in phase 2?

-when the water vapour in the atmosphere condensed, it formed oceans

-CO2 was removed from the atmosphere as it dissolved into the oceans

-green plants+algae evolved and absorbed some of the CO2 so they could carry out photosynthesis

-later, marine animals evolved (their shells/skeletons contained carbonates from the oceans)

-some of the carbon these organisms took in from the atmosphere and oceans became locked up in rocks+fossil fuels when they died

P2 what did the dissolved CO2 in oceans do?

went through a series of reactions to form carbonate percipitates that formed sediments on the seabed

P2 what happened when plants/plankton/marine animals died?

-they fall to the seabed and get burried by layers of sediment

-over millions of years, they become compressed and form sedimentary rocks,oil and gas (trapping carbon in them-helping to keep CO2 atmospheric levels reduced)

P2 what happened to deposits of plankton?

-form crude oil and natural gases

-these fossil fuels form reservoirs under the sea bed when they get trapped in rocks

P2 what happened to deposits of plants?

thick plant deposits make sedimentary rocks (coal)

P2 what happened to deposits of shells/skeletons?

calcium carbonate deposits from the shells/skeletons forms the sedimentary rock limestone

What happens in phase 3?

-green plants/algae produce oxygen through photosynthesis

-algae evolved first, around 2.7 biollion years ago

-then over around the next billion years, green plants evolved

-as oxygen levels built up over time, more complex life could evolve

-around 200 million years ago, the atmosphere reached a composition similiar to what it is today

What is the atmosphere like today?

about:

-80% nitrogen

-20% oxygen

-trace amounts of other gases (carbon dioxide, noble gases, water vapour)

What are some greenhouse gases?

-carbon dioxide

-methane

-water vapour

What do greenhouse gases do?

-act like an insulating layer in the earths atmosphere

-which allows the earth to be warm enough to suppo-which allows the earth to be warm enough to support lifert life

How do greenhouse gases keep the earth warm (greenhouse effect)?

-they don't absorb the incoming short wavelength radiation from the sun

-they do absorb the long wavelength radiation that gets reflected back off the earth

-then they re-radiate it in all directions- including to the earth

-the long wavelength radiation is thermal radiation, so it warms the earths surface

What are some forms of human activity that affect the amount of greenhouse gases in the atmosphere?

-deforistation

-burning fossil fuels

-agriculture (more farm animals produce methane through digestive processes)

-creating waste (decomposition of waste)

Why is there speculation to if climate change is real or not?

-it's very hard to make a model of the earths climate that isn't oversimplified

-stories in the media may be biased/ only some info is given

What can changing rainfall patterns (amount, timing and distribution) lead to?

-may cause some regions to get too much/ too little water

-may affect certain regions' ability to produce food

-may affect wild species ability to obtain water (-may affect wild species ability to obtain water (leading to decreased biodiversity)leading to decreased biodiversity)

What can an increase in global temperature lead to?

-polar ice caps melting

-causing a rise in sea levels

-increased flooding in coastal areas

-coastal erosion

-may affect certain regions' ability to produce food

-may affect wild species (leading to decreased biodiversity)

What consequences could climate change have?

-increase in global temperatures

-changing rainfall patterns (amount, distribution, timing)

-the frequency/severity of storms may increase

What are carbon footprints?

-Carbon footprints are a measure of the amount of carbon dioxide and other greenhouse gases released over the full life cycle of something

-This could be a service, an event, a product, etc.

Why is measuring carbon footprints so hard?

-Measuring carbon footprints is so hard as there are so many different factors to consider

What are things governments can do to reduce Carbon footprints?

-Governments could tax companies or individuals based on the amount of greenhouse gases they emit

-Governments can also put a cap on emissions of all greenhouse gases that companies makev

What are ways of reducing carbon footprints?

-renewable energy resources or nuclear energy could be used instead of fossil fuels

-Using more efficient processes could conserve energy and cut waste

-Lots of waste decomposes to release methane, so this will reduce methane emissions

-advances in technology

How can advances in technology help reduce carbon footprints?

-technology that captures the CO2 produced by burning fossil fuels before its released into the atmosphere, which can then be stored deep underground in cracks in the rock such as old oil wells

Why are governments reluctant to make reductions in carbon footprints?

-lots of governments are also worried that making these changes will impact on the economic growth of communities (bad for people's well-being)

-This is particularly important for countries that are still developing

Why is it hard to make international agreements to reduce emissions?

-As most countries don't want to sacrifice their economic development if they think others won't do the same, it's hard to make international agreements to reduce emissions

What happens during combustion of fossil fuels?

-during combustion, the carbon and hydrogen in the compounds are oxidised so that carbon dioxide and water vapour are released into the atmosphere

What happens when fuels incompletely combust?

-under these conditions, solid particles (particulates) of soot (carbon) and unburnt fuel are released and carbon monoxide can also be produced

How do fuels combust?

-when there's plenty of oxygen, fuels completely combust

-if there's not enough, fuels incompletely combust

How can particulates in the air cause problems?

-if particulates are inhaled, they can get stuck in the lungs and cause damage, which can lead to respiratory problems

-aid global warming

How do particulates cause global warming?

they're also bad for the environment, as they/their cloud, reflect sunlight back into space, meaning less light reaches the earth, causing global warming

Why is carbon monoxide dangerous to breath?

-Carbon monoxide (CO) is really dangerous as it can stop your blood from doing its proper job of carrying oxygen around the body

-It does this by binding to the haemoglobin in your blood that normally carries O2, so less oxygen can be transported round your body

-a lack of oxygen in the blood can lead to fainting, a coma or even death

Why is CO so dangerous?

-carbon monoxide is colourless and odourless, so hard to detect

When is sulfur dioxide released?

-Sulfur dioxide (SO2) is released during the combustion of fossil fuels, such as coal, that contain sulfur impurities

-the sulfur in the fuel becomes oxidised

How are nitrogen oxides created?

-Nitrogen oxides are created from a reaction between the nitrogen and oxygen in the air, caused by the heat of the burning (happens in the internal combustion engines of cars)

Why are nitrogen oxides and sulfur dioxide so dangerous?

-When these gases mix with clouds they form dilute sulfuric acid or dilute nitric acid, then falling as acid rain

-they cause respiratory problems if breathed in

Why is acid rain so bad?

-Acid rain kills plants, damages buildings and statues, and makes metal corrode

How is sulfuric acid created?

SO2 gas reacts with water to form sulfuric acid

How can you test for sulfur impurities in a fuel?

-You can test for sulfur impurities in a fuel by bubbling the gases from combustion through a solution containing universal indicator

-if the fuel contains sulfur, the gases will contain SO2, which will form sulfuric acid and turn the universal indicator red