AS - Unit 2 - Resources

Question 1

How does the Earth get most of its energy?

Answer 1

As electromagnetic radiation from the Sun

Question 2

What is the greenhouse effect?

Answer 2

The process in which the absorption and subsequent emission of infrared radiation by atmospheric gases warms the lower atmosphere and the planet’s surface

Question 3

Give three natural processes which produce carbon dioxide

Answer 3

Volcanic eruptions
Respiration of animals
Burning or decay of organic matter, such as plants

Question 4

What is the third most abundant greenhouse gas?

Answer 4

Methane

Question 5

Give three ways methane is produced and released into the atmosphere

Answer 5

It is;
emitted during the production of coal, natural gas and oil
A product of rotting organic waste in landfill sites
Released from certain animals, especially cows, as a by-product of digestion

Question 6

In water which bonds absorb infrared radiation?

Answer 6

the O-H bonds

Question 7

In methane which bonds absorb infrared radiation?

Answer 7

the C-H bonds

Question 8

Give 4 examples of the evidence of global warming on Earth

Answer 8

Ice and permafrost disappearing in the Arctic
Ice sheet melting into the oceans in the Antarctic
Tropical areas experiencing more frequent and destructive storms and floods
Glaciers are disappearing and extreme heat waves in Europe

Question 9

What 5 unpredictable changes has global warming brought to earth?

Answer 9

Rivers overflow due to excessive rainfall, in others drought-like conditions lead to water shortages
Longer growing season improving crop yield, but in others there is drought and disease ruining harvests
Storms and hurricanes are becoming more extreme, frequent and destructive
Sea ice in the Arctic is melting faster each year, fears that the Gulf Stream current may be cut off, leading to severe winters in northern Europe, including the UK
Increasing temperatures expend the water in the oceans. Together with extra water from melting land ice, sea levels are rising. If the Greenland ice sheet and the Antarctic glaciers where to melt, sea levels would rise by 6 metres, flooding land populated by millions of people

Question 10

What three targets were agreed within the EU regarding global warming?

Answer 10

20% of energy used in the EU will come from renewable sources by 2020
10% of the fuels used in transport will be biofuels by 2020
EU greenhouse gas emissions will be reduced to 20% below 1990 levels by 2020

Question 11

Give 4 ways of producing energy more cleanly

Answer 11

Wind turbines
Tidal power
Solar panels
Nuclear plants

Question 12

What is the troposphere?

Answer 12

The lowest layer of the Earth’s atmosphere, extending from the Earth’s surface up to about 7km (above the poles) and to about 20km (above the tropics)

Question 13

What is the stratosphere?

Answer 13

The second layer of the Earth’s atmosphere, containing the ‘ozone layer’, about 10km to 50km above the Earth’s surface

Question 14

Where in the atmosphere is ozone good and where is it bad?

Answer 14

Bad: ozone near to the Earth’s surface in the troposphere is in air pollutant with harmful effects on the respiratory systems of animals
Good: ozone in the upper atmosphere in the stratosphere protects living organisms by preventing harmful UV light from reaching the Earth’s surface

Question 15

How does the ozone layer help to protect living organisms on Earth?

Answer 15

It filters out the shorter UV light wavelengths, which are harmful to living organisms (less than 320nm) and converts this UV radiation into heat

Question 16

What are the three different types of UV radiation?

Answer 16

UV-a
UV-b
UV-c

Question 17

What is UV-a?

Answer 17

It has a wavelength of 320-400nm
It reaches the Earth’s surface, has less energy than the shorter wavelengths as is not as damaging
UV-a radiation doesn’t cause us much concern

Question 18

What is UV-b?

Answer 18

It has a wavelength of 280-320nm

It can cause sunburn and sometimes genetic damage, which can result in skin cancer if exposure to UV-b is prolonged

Question 19

What is UV-c?

Answer 19

It has a wavelength of 200-280nm

It is completely screened out by the ozone layer

Question 20

Why is it a worry that the ozone layer is depleting in regards to UV-b?

Answer 20

Any decrease in the ozone layer would allow more UV-b radiation to reach the surface of the Earth. This would cause increased genetic damage to living organisms

Question 21

How is ozone formed?

Answer 21

1. O2 molecules absorb a wavelength of less than 240nm
   This high-energy radiation is capable of breaking an O2 molecule into two oxygen atoms
   O2 + (radiation < 240nm) –> 2O
2. The O atoms then react with O2 molecules to form ozone molecules
   O2 + O –> O3 + heat

Question 22

How does the ozone layer work?

Answer 22

The ozone layer is broken down by wavelengths of 310nm turning O3 into O2 and O

O3 + (radiation < 310nm) –> O2 + O

The O atom then immediately reacts with O2 molecules in the ozone later:

O2 + O –> O3 + heat

And the cycle continues, this cycle keeps the ozone layer in a stable balance and a natural steady state is reached in which ozone is being formed at the same rate as it is being broken down

O2 + O O3

Question 23

What is the removal of ozone?

Answer 23

When an oxygen atom and an ozone molecule combine they form two O2 molecules
Luckily the removal rate is slow since the concentration of O atoms is very low
However human activity can affect this balance.

Question 24

How do CFCs destroy the ozone layer?

Answer 24

When CFCs reach the ozone layer the C-Cl bond is broken by the UV radiation from the sun
This produces a Cl radical
Cl radicals are extremely reactive and once in the ozone layer can react with the ozone and break it down
Cl + O3 –> ClO + O2
ClO + O –> Cl + O2
where the overall equation is O3 + O –> O2
The Cl radical is regenerated at the end and continues to break down ozone again and again in a cycle

Question 25

What else can destroy ozone other than CFCs?

Answer 25

Nitrogen oxide from lightning or aircraft engines

Question 26

What three main things are emitted from internal combustion engines?

Answer 26

Carbon monoxide Oxides of nitrogen Unburnt hydrocarbons

Question 27

Give some facts about carbon monoxide

Answer 27

Poisonous gas, produced from the incomplete combustion of hydrocarbons. Majority of carbon monoxide production comes from traffic pollution in urban areas Can exist in the environment for one month before being oxidised to carbon dioxide For humans, the haemoglobin in our blood carries oxygen to our tissues, carbon monoxide binds strongly to this haemoglobin reducing the amount of oxygen supplied to tissues and organs.

Question 28

Give some facts about oxides of nitrogen

Answer 28

Produced in the high temperature process where air is drawn into the cylinder along with fuel in the internal combustion engine. They are made by some of the nitrogen in the air being oxidised by the oxygen. The two oxides of nitrogen are: Nitrogen monoxide Nitrogen dioxide high concentration of these gases in urban areas with high traffic levels Nitrogen dioxide is responsible for the formation of low level ozone, most of the NO2 is converted into nitric acid, a contributor to acid rain. They are also respiratory irritants.

Question 29

Which two unburnt hydrocarbon compounds are of particular concern and why?

Answer 29

Benzene Buta-1,3-diene Known to be human carcinogens

Question 30

Give some facts about unburnt hydrocarbons

Answer 30

Once released into the atmosphere, the unburnt hydrocarbons and nitrogen dioxide react together to form low-level ozone The energy for this is provided by sunlight The mechanism responsible for this involves radicals Low-level ozone is a serious concern causing breathing difficulties and increasing susceptibility to infections Conc of low-level ozone builds up on humid sunny days when the still air contains large quantities of hydrocarbons and oxides of nitrogen

Question 31

Explain the structure of a catalytic converter

Answer 31

It is made from platinum, rhodium, and palladium | It is supported on a honeycomb mesh. This is used to provide a large surface area

Question 32

How do catalytic converters work?

Answer 32

The hot exhaust gases pass over the catalytic surface and the harmful gases are converted to less harmful products. These are then released into the atmosphere 1. The catalyst provides a surface on which the reaction takes place 2. The CO and NO gas molecules diffuse over the catalytic surface of the metal. Some of the molecules are held on to the metal surface by adsorption 3. Temporary bonds are formed between the catalytic surface and the gas molecules 4. These bonds hold the gas molecules in the correct position on the metal surface, where they react together 5. After the reaction, the CO2 and N2 products are desorbed from the surface and diffuse away from the catalytic surface

Question 33

What are the two types of catalytic converter typically in use?

Answer 33

Oxidation catalysts | Three-way catalyst

Question 34

In what vehicle is an oxidation catalytic converter used?

Answer 34

Used in vehicles with diesel engines to decrease emissions of carbon monoxide and unburnt hydrocarbons They contain a complex filter system, and remove particulate matter and nitrogen oxides

Question 35

What reactions take place in an oxidation catalytic converter?

Answer 35

2CO(g) + O2(g) ----> 2CO2(g) | C12H26(l) + 18 1/2 O2(g) ----> 12CO2(g) + 13H2O(l)

Question 36

In what vehicle is a three-way catalytic converter used?

Answer 36

It is fitted in vehicles with petrol engines | In this system, nitrogen monoxide reacts with carbon monoxide to form the non-toxic gases nitrogen and carbon dioxide

Question 37

What reaction takes place in a three-way catalytic converter?

Answer 37

2NO(g) + 2CO(g) ----> N2(g) + 2CO2(g)

Question 38

What is adsorption?

Answer 38

The process that occurs when a gas, liquid or solute is held to the surface of a solid or, more rarely, a liquid

Question 39

What are the 12 principles of green chemistry?

Answer 39

1. Prevention 2. Atom economy 3. Less hazardous chemical synthesis 4. Designing safer chemicals 5. Safer solvents and auxiliaries 6. Design for energy efficiency 7. Use of renewable feedstocks 8. Reduce derivatives 9. Catalysts 10. Design for degradation 11. Real-time analysis for pollution prevention 12. Inherently safer chemistry for accident prevention

Question 40

How are green bags produced?

Answer 40

Bacteria is used to ferment vegetable oils and sugars in the waste and converts this into plastics It took nearly 15 years to perfect this technique

Question 41

How are companies able to cut down on the amount of water and energy needed to produce what they need?

Answer 41

The use of catalysts

Question 42

How has ibuprofen become more 'green'?

Answer 42

It was originally synthesised in 6 steps with less than 40% atom economy. A new way of producing ibuprofen has been developed where it has 3 catalytic steps and a 99% atom economy. And any waste produced is either recycled or is sold on as a useful by-product

Question 43

Give 7 ways CO2 can be used to be helpful to humans

Answer 43

``` In foam As a solvent For decaffeinated coffee For beer For dry cleaning Toxic waste treatment Chemical synthesis ```

Question 44

How is CO2 used in foam?

Answer 44

CO2 has replaced CFCs as the blowing agent to produce foam. The company is using CO2 waste from industrial or natural sources, ensuring there is no net increase in global CO2.

Question 45

How is CO2 used for beer?

Answer 45

CO2 produces the natural fizz in beer, but can also be used to extract the characteristic flavour of beer from hops