Chemistry of the Atmosphere

Question 1

What are the percentages of gases in the air?

Answer 1

Oxygen - 21%
Nitrogen - 78%
CO2 - 0.04%
Argon - 0.9%

Question 2

How can scientists measure historic atmospheric composition?

Answer 2

Analysing tiny air bubbles trapped in ICE CORES in the poles

The air bubbles were trapped as the snow and ice was laid down tens of thousands of years ago and provide a snapshot of what our atmosphere was like back then

Question 3

What was Earth’s early atmosphere like?

Answer 3

Earth used to be molten for millions of years, where there was NO ATMOSPHERE

When the molten materials solidified, volcanoes were formed which released gases from Earth’s interior.

Gravity prevented these gases from escaping forming an ATMOSPHERE

There was mostly CO2 and water vapour present, and little or no oxygen present

When the earth cooled the water vapour condensed and formed OCEANS

CO2 is a water soluble gas, so dissolved in the oceans which reduced the levels of CO2 in the atmosphere

Question 4

How were oxygen levels increased in the atmosphere?

Answer 4

Primitive plants and algae begun PHOTOSYNTHESISING which used up CO2 from the atmosphere and released OXYGEN

Over long periods of time the oxygen increase and the CO2 decreased

Marine algae are thought to be responsible for about 90% of all the atmospheric oxygen produced

Question 5

What happens when shortwave light radiation from the sun hits the earth?

Answer 5

It hits the Earth’s surface and energy is absorbed then re-emitted from the surface as INFRARED RADIATION (heat)

Question 6

What do greenhouse gases do?

Answer 6

They can ABSORB and STORE the infrared radiation which is emitted from the surface of the Earth which can result in the Earth becoming hotter

Question 7

What are some examples of greenhouse gases?

Answer 7

CO2, Methane and water vapour

Question 8

What is the enhanced greenhouse effect?

Answer 8

Where increasing levels of gases such as CO2 or Methane cause significant upset in the Earth’s natural conditions by trapping extra heat energy

Question 9

How can carbon dioxide be exposed to the atmosphere?

Answer 9

Combustion of wood and fossil fuels, respiration of plants and animals and thermal decomposition of carbonate rocks

Question 10

How can methane be exposed to the atmosphere?

Answer 10

Digestive processes of animals, decomposition of vegetation and bacterial action in swamps and rice fields

Question 11

How do we match the increasing energy demands of the growing human popualtion?

Answer 11

Burning fossil fuels as a cheap and reliable energy source and more landfill sites to dispose of waste which increases emissions of methane by decomposition

Question 12

How does deforestation affect the climate?

Answer 12

Trees remove CO2 from the atmosphere during photosynthesis, so by mass removal of large forests, the amounts of atmospheric CO2 increases as a result

Question 13

How can we estimate past climate conditions?

Answer 13

Analysis of fossil records, tree rings, gas bubbles trapped in ice, etc

However none of these methods provide as accurate data as we have today, and they do not represent data on a global scale

Question 14

What are some effects of climate change?

Answer 14

Rising sea levels, frequent and intense droughts, storms, infrequent weather, extreme heat waves and rainfall, etc

Question 15

What causes rising sea levels?

Answer 15

Melting of polar ice caps and glaciers due to warming global temperatures.

Question 16

What are the effects of rising sea levels?

Answer 16

Erosion of coastal regions, habitat destruction for bids, fish and plants

Low lying cities are likely to see flooding and permanent loss of usable land

Question 17

What are some effects of droughts?

Answer 17

Crop failure, collapse of agricultural production and starvation

Question 18

What is the life cycle assessment?

Answer 18

A technique used to assess the environmental impact associated with all the stages throughout the life cycle of a product, service or event

It takes into account raw extraction of the materials, how it is manufactured, how it is distributed and how it is disposed of at the end of its life

It is a very difficult process because there are so many factors to consider, such as the emissions released in sourcing all of the parts of a computer!

Question 19

How can we quantify emissions of CO2?

Answer 19

In terms of a CARBON FOOTPRINT

Question 20

What is a carbon footprint?

Answer 20

The amount of carbon dioxide generated by a persons’ activities

Question 21

How can we reduce our carbon footprint?

Answer 21

• Using renewable energy supplies (eg. solar or wind energy instead of burning fossil fuels)
• Governments and global organisations are slowly switching to greener and more sustainable sources of energy
• Cutting unnecessary journeys
• Using public transport
• Reducing consumption of meat
• Recycling
• Electric vehicles

Question 22

What are the challenges with reducing our carbon footprint?

Answer 22

• Governments tend to be slow to act on these issues as they fear a negative impact on their economy
• Difficult to convince people to change their ways
• Too expensive and too much luxury to sacrifice

Question 23

What are fossil fuels?

Answer 23

Coal, oil, natural gas, etc

Question 24

How are some fossil fuels obtained?

Answer 24

Some non-renewable fossil fuels are obtained from crude oil by fractional distillation

Question 25

What is carbon monoxide?

Answer 25

An extremely poisonous gas which combines with haemoglobin in blood and prevents it from carrying oxygen, reducing oxygen supply to brain which can cause fainting, coma or death

Colourless, odourless, difficult to detect

Question 26

What is soot?

Answer 26

Clumping together of carbon particles released from incomplete combustion form SOOT

Causes respiratory problems and accelerates corrosion on infrastructure

Question 27

What is sulphur dioxide?

Answer 27

Colourless, pungent smelling gas responsible for acid rain, which can cause corrosion to metal and damages aquatic organisms, pollutes crops and water supplies and irritates lungs, throat and eyes

Question 28

What are oxides of nitrogen?

Answer 28

Come largely from vehicle exhausts and also contribute to acid rain

They produce a photochemical smog and breathing difficulties, in particular for asthma sufferers

Question 29

How did the earth atmosphere change over time?

Answer 29

• water vapour condensed and formed the oceans (reduced h2o in atmosphere)
• co2 dissolved into oceans (reduced co2)
• dissolved co2 formed carbonates