C13/14

Question 1

What is the composition of the atmosphere and how long has it been like this

Answer 1

About four-fifths (approximately 80%) nitrogen
About one-fifth (approximately 20%) oxygen
Small proportions of various other gases, including carbon dioxide, water vapour and noble gases
Been like this for 200 million years

Question 2

Why is evidence of the early atomsphere limited

Answer 2

The time scale is 4.6 billion years and this is too big

Question 3

What is the theory for Earth’s atmosphere today?

Answer 3

First billion years of the Earth’s existence there was intense volcanic activity that released gases that formed the early atmosphere
Water vapour condensed to form the oceans.
At the start of this period the Earth’s atmosphere may have been like the atmospheres of Mars and Venus today, consisting of mainly carbon dioxide with little or no oxygen gas.
Volcanoes also produced nitrogen which gradually built up in the atmosphere and there may have been small proportions of methane and ammonia.
When the oceans formed carbon dioxide dissolved in the water and carbonates were precipitated producing sediments, reducing the amount of carbon dioxide in the atmosphere.

Question 4

How did oxygen levels increase

Answer 4

Algae and plants produced the oxygen that is now in the atmosphere by photosynthesis

Question 5

What did the increase in oxygen mean for the Earth

Answer 5

Algae first produced oxygen about 2.7 billion years ago and soon after this oxygen appeared in the atmosphere.
Over the next billion years plants evolved and the percentage of oxygen gradually increased to a level that enabled animals to evolve

Question 6

How did carbon dioxide decrease

Answer 6

Algae and plants decreased CO2 by photosynthesis

CO2 was also decreased by the formation of sedimentary rocks and fossil fuels that contain carbon

Question 7

What do humans use earths resources for

Answer 7

To provide warmth, shelter, food and transport

Question 8

What do natural resources provide

Answer 8

Supplemented by agriculture, natural resources provide food, timber, clothing and fuels

Question 9

What are finite resources used for

Answer 9

Finite resources from the earth, oceans and atmosphere are processed to provide energy and materials

Question 10

What is potable water

Answer 10

Water that is safe to drink

This is not pure water in a chemical sense as it contains dissolved substances

Question 11

What is fresh water

Answer 11

Water that collects in the ground and in lakes and rivers

Question 12

How is most potable water produced

Answer 12

Choosing appropriate source of fresh water
Passing water through filter beds
Sterilisation

Question 13

What are some sterilisation agents used for cleaning water

Answer 13

Ultraviolet light
Chlorine
Ozone

Question 14

When is desalination used

Answer 14

When supplies of fresh water are limited

Question 15

How is desalination done

Answer 15

Distillation
Processes that use reverse osmosis
These require lots of energy

Question 16

What does sewage treatment include

Answer 16

Screening and grit removal
Sedimentation to produce sewage sludge and effluent
Anaerobic digestion of sewage sludge
Aerobic biological treatment of effluent (to breakdown organic matter including microbes)

Question 17

What is waste water

Answer 17

Urban lifestyles and industrial processes produce large amounts of waste water that require treatment before being released into the environment

Question 18

What are some new ways of extracting copper from low grade ore

Answer 18

Phytomining and bioleaching

These avoid mining methods and digging, moving and disposing of large amounts of rocks

Question 19

What is phytomining

Answer 19

Plants absorb metal compounds. The plants are harvested and then burned to produce ash that contains metal compounds

Question 20

What is bioleaching

Answer 20

Uses bacteria to produce leachate solutions that contain metal compounds

Question 21

How are metal compounds processed to produce metal

Answer 21

Copper can be obtained from solutions of copper compounds by displacement using scrap iron or by electrolysis

Question 22

What does LCA stand for and what is it’s purpose

Answer 22

Life cycle assessments (LCAs) are carried out to assess the environmental impact of products

Question 23

What do we measure to determine the LCA

Answer 23

• extracting and processing raw materials
• manufacturing and packaging
• use and operation during its lifetime
• disposal at the end of its useful life, including transport and
distribution at each stage.

Question 24

Why can an LCA be a subjective process ( opinion )

Answer 24

Use of water, resources, energy sources and production of some wastes can be fairly easily quantified.
However, allocating numerical values to pollutant effects is less straightforward and requires value judgements, so LCA is not a purely objective process

Question 25

Why can an LCA be adapted or unfair

Answer 25

Selective or abbreviated LCAs can be devised to evaluate a product but these can be misused to reach pre-determined conclusions, eg in support of claims for advertising purposes

Question 26

What does reduce, reuse and recycling do

Answer 26

The reduction in use, reuse and recycling of materials by end users reduces the use of limited resources, use of energy sources, waste and environmental impacts

Question 27

How do materials use up resources

Answer 27

Metals, glass, building materials, clay ceramics and most plastics are produced from limited raw materials.
Much of the energy for the processes comes from limited resources.
Obtaining raw materials from the Earth by quarrying and mining causes environmental impacts

Question 28

What happens to glass bottles after use

Answer 28

Glass bottles can be crushed and melted to make different glass products.
Other products cannot be reused and so are recycled for a different use

Question 29

How are metals recycled

Answer 29

Metals can be recycled by melting and recasting or reforming into different products.
The amount of separation required for recycling depends on the material and the properties required of the final product.
For example, some scrap steel can be added to iron from a blast furnace to reduce the amount of iron that needs to be extracted from iron ore

Question 30

formation of deposits of limestone, coal, crude oil and natural gas.

Answer 30

. Idea of becoming compressed and trapping rock

Question 31

What is a source of atmosphric pollution?

Answer 31

The combustion of fuels is a major source of atmospheric pollutants.

Question 32

What are realsed to the atmosphere when fuels are burnt

Answer 32

The gases released into the atmosphere when a fuel is burned may include carbon dioxide, water vapour, carbon monoxide, sulfur dioxide and oxides of nitrogen. Solid particles and unburned hydrocarbons may also be released that form particulates in the atmosphere.

Question 33

describe how carbon monoxide, soot (carbon particles), sulfur dioxide and oxides of nitrogen are produced by burning fuels

Answer 33

Incomplete combustion of hydrocarbons in coal and crude oil releases carbon particulates (soot) and carbon monoxide

Combustion of fossil fuels with sulfur impurities

Reaction between nitrogen and oxygen with the heat of buring

Both mean (nitrogen and sulphur become oxdised)

Question 34

What is the problem with increased pollutants?

Answer 34

Carbon monoxide is a toxic gas. It is colourless and odourless and so is not easily detected.
Sulfur dioxide and oxides of nitrogen cause respiratory problems in humans and cause acid rain.
Particulates cause global dimming and health problems for humans.

Question 35

state examples of natural products that are supplemented or replaced by agricultural and synthetic products

Answer 35

Rubber (from tree sap) - now polymers (use in tires)

High crop yields due to development of fertilsiers.

Question 36

What need to be removed from each bit of waste water

Answer 36

.

Sewage and agricultural waste water require removal of organic matter and harmful microbes.

Industrial waste water may require removal of organic matter and harmful chemicals.

Question 37

Pros and cons of sewage treatment compared with desalination

Answer 37

Desalination requires more energy

Sewage teatemnets require more processs (and people don’t want tp drink water that was sewage)