C6.3 - Earth Systems

Question 1

What substances form the earths atmosphere from highest to least %

Answer 1

• nitrogen
• oxygen
• argon
• carbon dioxide
• trace amounts of other gases

Question 2

What was the atmosphere like billions of years ago

Answer 2

• lots of volcanic activity
• release huge volumes of water vapour & carbon dioxide
• as earth cooled, water vapour condensed, formed oceans
• leaving atmosphere as mostly carbon dioxide
• small amounts of other gases: methane, ammonia
• little/no oxygen

Question 3

How is it thought an oxygen-rich atmosphere developed on earth

Answer 3

• plants & algae appeared
• photosynthesis reduced amount of CO2 (absorbed) & increased amount of oxygen (released)
• first, oxygen reacted with metals in rocks, produce metal oxides
• as most of metals becomes oxidised, free oxygen began to accumulate in atmosphere
• eventually oxygen-rich atmosphere

Question 4

Pollutants

Atmospheric pollutants

Answer 4

Substances released into environment that may cause harm to living things

Atmosphere = released into air

Question 5

Examples of atmospheric pollutants as a result of burning fossil fuels

Answer 5

• carbon monoxide
• particulates
• oxides of nitrogen (NO, NO2)
• sulfur dioxide

Question 6

How is carbon monoxide produced

Answer 6

During incomplete combustion of fuels that contain carbon

(coal, wood, in vehicle engine)

(in poor supply of air)

Question 7

Problems with carbon monoxide

What does it cause

Answer 7

• toxic gas
• colourless, no smell / taste
• when breathed in, attached to haemoglobin protein in red blood cells
• reduces amount of oxygen bloodstream cab carry

= drowsiness, difficulty breathing, death

Question 8

How are particulates produced

Answer 8

Small particles

• formed during incomplete combustion (in vehicle engines)
• in industrial processes (metal extraction)

Question 9

Why are particulates dangerous

What do they cause

Answer 9

• smallest particulates settle deep in lungs when breathed in

= disease (bronchitis), breathing problems, increases chance of heart disease

Question 10

How are oxides of nitrogen formed (NOx)

Answer 10

• nitrogen & oxygen in air don’t normally react
• nitrogen & oxygen react at high temps in vehicle engines
• forming nitrogen monoxide (NO)
• NO oxidised in air
• forming nitrogen dioxide (NO2)

Question 11

Why are oxides of nitrogen dangerous

Answer 11

• nitrogen dioxide dissolves in moisture in clouds, forming acidic solutions
• falls as acid rain

Question 12

How does sulfur dioxide form

What problems does sulfur dioxide cause

Answer 12

Fossil fuels contain small amounts of sulfur compounds
Impurities form sulfur dioxide when fuel burnt

• acid rain
• breathing difficulties

Question 13

Acid rain

What problems can it cause

Answer 13

Rain containing acidic gases from air

• erodes stonework
• corrodes metals
• can kill trees
• can kill living things in rivers / lakes

Question 14

Greenhouse effect

Answer 14

Interaction of infrared radiation with molecules in the atmosphere
Reducing the transfer of energy to space

Keeps earth & atmosphere warm enough for living things to exist

Question 15

Explain how the greenhouse effect works

Answer 15

1. Energy transferred by radiation from sun reaches earths surface
2. Radiation warms up earths surface
3. Infrared radiation emitted by earths surface
   - some goes directly into space
   - some absorbed by greenhouse has molecules in atmosphere
4. Greenhouse gas molecules emit infrared radiation in all directions, warming earths surface & atmosphere

Question 16

How are different greenhouse gases released into the atmosphere

Answer 16

Carbon dioxide: combustion of fossil fuels
Methane: rice paddy fields, cattle, landfill waste sites, use of natural gas

Others: human / anthropogenic activities

Question 17

What causes an enhanced greenhouse effect

Answer 17

• release of additional greenhouse gases (by human / anthropogenic activities)
• increases temp of earths atmosphere

Question 18

What can the enhanced greenhouse effect cause

Answer 18

Global warming:

• melting ice caps
• rising sea levels

Climate change

• altered weather patterns
• flooding
• problems with farming
• problems with disease control

Question 19

How can greenhouse house emissions be reduced

Answer 19

• reduce consumption of fossil fuels (use biofuels)
• use renewable energy resources (wind, solar energy) to generate electricity
• stop carbon dioxide escaping when fuels used (carbon capture)

Question 20

What is done to protect against the effects of global warming

Answer 20

• flood barriers
• planting different crops
• designing buildings to withstand high winds

Question 21

Carbon capture

Answer 21

Process by which carbon dioxide emissions are collected & stored & not allowed into atmosphere

Question 22

Where does tap water originally come from

Answer 22

• lakes
• reservoirs
• aquifers
• rivers
• waste water

Question 23

Aquifer

Answer 23

Layer of rock that stored water underground

Question 24

What must be removed from water to make it safe to drink

Answer 24

• insoluble materials (leaves, particles from rocks / soil)
• soluble substances (salts, pollutants: pesticides, fertilisers)
• microorganisms

Question 25

Potable water

Answer 25

Water safe for drinking

Question 26

Stages in water treatment of fresh water

Answer 26

• passed through screen (bars of metal placed close together), catch large objects (leaves, twigs)
• settlement tank: sand & soil settle out
• aluminium sulfate & lime added, small particles of dirt clump together & sink to bottom, sludge dumped in landfill site & forms mud
• passed through filter (made of fine sand), removes remaining particles (mud, grit) so water clear
• small amount of chlorine added to kill bacteria
• pH checked & corrected so it is neutral
• stored in large tanks & service reservoirs, ready to be pumped to where its needed

Question 27

What process is used to treat salt water

Answer 27

Desalination

= removes dissolved salts from water

Question 28

Desalination (to removed salts from salt water)

Answer 28

Small scale: ‘reverse osmosis’ using ‘ultrafilters’ used to filter out salts

Large scale: simple distillation used

Question 29

In what countries would desalination be worthwhile

Answer 29

• fresh water supplies limited

- cost of energy resources is low