Topic 9- chemistry of the atmosphere

What are the main gases in the earths atmosphere

20% oxygen, 80% nitrogen, <1% other gases (water vapour, carbon dioxide, noble gases)

What was the arts atmosphere like in the first billion years

Intense volcanic activity which produced lots of CO2, water vapour and nitrogen along with smaller amounts of methane and ammonia

Which planet (today) was earths atmosphere most like

Mars and Venus

What happened to the earth as it began to cool

The water vapour in the atmosphere condensed into liquid water forming the oceans

What happened after the oceans formed

Oceans forming allowed CO2 to dissolve in them where it could form carbon precipitated and then finally become sediments in the seabed

What happened about 2.7 billion years ago

Algae evolved and then over the next billion years green plants evolved. They both absorbed CO2 in the atmosphere and used it for photosynthesis where it also released oxygen in the atmosphere

What did the reduction in carbon dioxide and increase in oxygen allow

Allowed more complex life to evolve eg animals

How did the algae and green plants lock away carbon

When the algae and green plants died they sunk to the seabed and became buried in layers of sediment and over millions of years they became compressed to form sedimentary rock, oil or gas which trapped the carbon to stop it from getting back into the atmosphere

What is crude oil and natural gas formed from

(Deposits of) Dead plankton

What do crude oil and natural gas form

Reservoirs under the seabed

What is coal and what is it made from

A sedimentary rock from thick dead plant deposits

What is limestone and what is it made of

A sedimentary rock made of calcium carbonate from shells and skeletons of marine organisms

Where do we get the evidence for earths early atmosphere

Volcanoes, rocks, other planets, living things

What is the atmosphere

A mixture of gases that surround the earth in order to keep the perfect amount of suns energy (to support life)

How does the green house effect work

Sun emits short wavelength radiation which passes through earths atmosphere as it isn’t absorbed by green house gases. The short wavelength radiation reaches earths surface, is absorbed and then remitted as long wavelength radiation. Some of this radiation escapes into space and some of it is absorbed by greenhouse gases in atmosphere. The green house gases then reradiate in all directions. Because the long wavelength radiation is thermal it results in global warming

Why is global warming happening

Because human produce lots of greenhouse gases the concentration in atmosphere is increasing and so greenhouse effect is getting stronger leading to global warming

Why is it hard to determine the consequences of climate change

There are lots of variables to consider

What are the main reasons CO2 is increasing and why

Burning of fossil fuels which release carbon that was locked up inside as CO2, deforestation which leads to less photosynthesis so less CO2 is being removed from the atmosphere

What are the main reasons methane is increasing and why

Increasing global population sans more food needs to be produced leading to increase in farm animals eg cows which produce methane during digestion which gets released into the atmosphere, huge amounts of waste production which releases methane as it’s decomposed by microorganisms

What are the consequences of climate change

1) frequency and severity of extreme weather events eg droughts, hurricanes, floods

2) sea level rise from higher temperature either causing ice caps and glaciers to melt or from water in the oceans expanding from warming- leading to flooding in coastal areas and coastal erosion

3) species perfectly adapted to environment might not be able to survive anymore leading ti decrease in biodiversity or they may adapt or migrate to regions with better conditions

What is carbon footprint

The total amount of carbon dioxide and other greenhouse gases emitted over something’s (product, service, event) entire lifecycle

What are the benefits of carbon footprints

Shows how environmentally damaging something is (so helps decide if it’s worth the cost), can identify the most polluting activities in order to reduce their emissions

Why is measuring carbon footprint really hard or sometimes impossible

So many factors to consider eg manufacturing process and transportation

Ways to reduce carbon footprint

1) Using renewable energy sources, more efficient manufacturing processes which would use less energy and produce less waste

2) Government introducing new laws or taxing companies based on how many greenhouse gases they emit

3) Carbon capture technology (captures CO2 before it’s released into atmosphere)- can then be stored deep underground in cracks in rocks eg old oil wells

Problems with reducing carbon footprint

1) renewable energy is often more expensive than fossil fuels and entire economy is based on fossil fuels (making it hard to change)

2) Governments worry that prioritising environment may cause the economy to suffer making international agreements difficult

3) some individuals aren’t willing to make changes to their lifestyle to reduce carbon footprint

What are the products of complete combustion

Water and carbon dioxide

What are the products of incomplete combustion

Carbon monoxide and solid particles (particulates) of carbon (soot)

What are the problems with carbon particulates

If soot is inhaled it can get stuck in lungs and damage them leading to respiratory problems, can cause smog which reflects sunlight back into space leading to less light reaching earth causing global dimming.

What are the problems with carbon monoxide

When carbon monoxide is inhaled it diffuses into our blood and binds to our haemoglobin (same place oxygen binds) so less oxygen gets transported around body leading to fainting, comas or death

Why is carbon monoxide hard to detect

It’s a colourless, odourless gas

What are the problems with sulfur dioxide and nitrogen oxide

Lung damage leading to respiratory problems, when the gases mix with water in clouds they dissolve to form dilute sulfuric acid or dilute nitric acid which then falls as acid rain which damages certain buildings and statues, corrodes metals and damages plants

How does acid rain damage plants

They either land directly on the plant ore make soil more acidic making it harder for plants to grow

How is sulfur dioxide formed

When hydrocarbons burn with impurities like atoms of sulfur so oxidises to sulfur gas

How is nitrogen oxide formed

When nitrogen and oxygen from the air to react together

Why does oxygen and nitrogen in the air not normally react with each other

Requires high temperatures, often reached inside internal combustion engines eg cars