C10- The Earth's Atmosphere

Question 1

What is the difference between finite and renewable sources of energy?

Answer 1

• Finite resources are those that are being used up at a faster rate than they can be replaced. Finite resources include fossil fuels such as crude oil, coal.
• Renewable sources are those that can be replaced at the same

Question 2

Give examples of finite sources of energy? (4)

Answer 2

Finite resources:

• metal ores used to extract metals.
• crude oil used to make polymers and petrochemicals.
• limestone to make cement and concrete. Crude oil to make petrol, diesel and kerosene that we use for transport.
• coal

Question 3

Give examples of renewable sources of energy? (3)

Answer 3

Renewable sources:

• biofuels
• cotton
• wood ( regenerated in our lifetime)

Question 4

Why do humans use energy sources?

Answer 4

• Enough energy to keep warm,
• shelter
• energy to cook food.
• fuel for transport.

Question 5

What are the two ways crude oil can be used?

Answer 5

1) crude oil used to make polymers and petrochemicals.

2) Crude oil to make petrol, diesel and kerosene that we use for transport.

Question 6

Suggest what these natural sources can be used for and their alternate synthetic product? (6)

Answer 6

1) Wool- used for clothes and carpets- acrylic.
2) Cotton- clothes and textiles- polyester.
3) Silk- clothes- nylon
4) Linseed oil - paint- acrylic resin.
5) rubber- tyres- synthetic polymers.
6) Wood- construction- PVC, composites(MDF)

Question 7

What is sustainable development? List a few sustainable development goals.

Answer 7

Sustainable development that meets the current needs of the generation without compromising the ability of future generations to meet their own needs.

SD Goals:

• clean water sanitation.
• gender equality.
• climate action
• zero hunger.

Question 8

How do chemists play an important role in sustainable development? (4)

Answer 8

1) Developing biodegradable polymers as plastic gets trapped in the oceans and landfills as they take long times to degrade- biodegradable does not collect in the seas and does not take a long time to breakdown- less space in landfills.
2) Developing polymers made from renewable resources such as cellulose or fermenting sugars.
3) Developing biofuels.
4) Improving efficiency of farming.

Question 9

How does potable water differ from pure water(3)

Answer 9

1) Potable water is water that has been treated or is naturally safe for humans to drink and is essential for life. 2) Potable water is not pure water because pure water contains H20 molecules whereas potable water can contain lots of other dissolved substances.
3) In potable water, the levels of dissolved salts aren’t too high that it has a pH between 6.5 and 8.6 and only has minimal and low levels of microbes.

Question 10

Where can potable water be extracted from? (2)

What still has to be done to the water from freshwater sources?

Answer 10

1) Surface water eg lakes, rivers, and reservoirs
2) Groundwater( in rocks called aquifers that trap water underground)

Though it has low levels of dissolved substances, water from these freshwater sources still need to be treated to make it safe before it can be used.

Question 11

Describe the process of the purification of water (3).

Answer 11

1) Choose a source of fresh water
2) Pass water through filter beds
- Giant metal, wire mesh that screens out large items such as twigs and branches.
- Pass water over a filter bed which is graven and then sand bed to filter out any other solid bits and this acts as a fine filter because it removes large items but does not remove any dissolved salts or microbes because they are too small.
3) Sterilization- water is sterilised to kill any harmful bacteria or microbes and this can be done by bubbling chlorine gas through it or by using ozone or UV light.

Question 12

What tests can be done on the water to test for ions? (3)

Answer 12

1) Precipitate test- identify halogen ions or the transition metals present due to coloured precipitate forming.
2) Sulphate ions- BaCl
3) Carbonate ions- HCL acid- fizzing or effervescence.

Question 13

Why do we put Cl in water?

Answer 13

To kill harmful bacteria or microbes in water.

Question 14

What has to be done in countries where there’s not enough surface or groundwater?

Answer 14

• Sea water must be treated by desalination to provide potable water.

Question 15

What chemical can be added to the water supply in the purification of water?

Answer 15

• Floride( which is good for teeth) but is controversial as people aren’t given a choice whether they consume them or not.

Question 16

PAG for desalination of salty water? (4)

Control variables?

Answer 16

1) First test pH of water using a pH meter - pH too high or too low, neutralise it through a titration but use a pH meter to see if the solution is neutral rather than an indicator so it does not contaminate the water.
2) Test the water for NaCl- the main salt in seawater- test for sodium ions, do a flame test on a small sample- flame will be yellow.
Cl ions- take a sample of water and add a few drops of dilute nitric acid followed by silver nitrate solution- Cl ions- white precipitate.
3) Distil water- pour salty water into a distillation apparatus- heat the round flask and water will boil and form steam- the water vapour will pass through the condenser and leave any dissolved salts be left behind. Water vapour will condense back
4) Retest distil water for NaCl to check that it has been removed and also retest the pH of the water with a pH meter to check if it’s netural

Control:
- the heat- flame from the experiment as large amounts of water can spill so control the bunsen burner carefully.
-

Question 17

Besides distillation, what’s another way seawater can be treated? (2)

Disadv of this process?

Suggest one piece of equipment that could be sed to improve the distillation?

Answer 17

• Using membranes- like reverse osmosis and salty water is passed through a membrane that only allows water molecules to pass through. Ions and larger molecules are trapped by the membrane so separated from the water.
• Both distillation and reverse osmosis need loads of energy so they’re really expensive and not practical for producing large quantities of fresh water but reverse osmosis uses less energy than distillation.

Disadv: does not involve heating n requires high pressure. Even though pressure is increased, lots of countries have not developed the technology to do this and they use fossil fuels to heat the water.

1) Liebig condenser can cause water to more efficient cooled.

Question 18

What are the 3 ways potable water can be made?

Answer 18

1) Distillation.
2) Reverse Osmosis.
3) Purification.

Question 19

What are disadv of desalination?(3)

Answer 19

1) Process requires large amount of energy often.
2) small traces of salt are left behind.
3) Affect the aquatic life as salt is thrown back and that can disrupt the conc of salt in sea which can affect the life.

Question 20

% of fresh water to sea water?

Answer 20

97% of the earth’s water on Earth is in the oceans and sea’s with the remaining 3% being fresh water.

Question 21

List some sources as to where the waste water comes from and what needs to be removed from it? (3)

Why does components need to be removed from sewage from domestic or agriculture sources?

Answer 21

1) Domestic waste water- baths, toilets, showering, washing- organic matter and harmful microbes needs to be removed.
2) Agriculture run off- fields and slurry from animals- removing organic matter and harmful microbes
3) Industrial processes in the factory produce lots of waste wateras well - removing organic matter and harmful chemicals

• Sources have to be treated before being put back in freshwater sources like rivers and rike otherwise it would make them v polluted and pose health risks.

Question 22

Describe the process of the sewage treatment.(4)

Answer 22

1) Screening- waste water is pass through a metal mesh which removes any solid items and these solid items can be compacted and send to landfill as well as grit.
- Grit removal- filter and remove grit and inorganic matter is also removed.

2) Primary treatment;
- Sedimentation to produce sludge and effluent- the heavier suspended solids sink to the bottom to produce sludge and light effluent floats on top. 70% of the solid has been removed.Phosphates are added to help treat process.

3) Secondary treatment:
1) Aerobic digestion- the effluent from the settlement tank is removed and treated by biological aerobic digestion. This is when air is pumped through the water to encourage aerobic useful bacteria to feed on any remaining organic matter and harmful microorganisms still present, breaking them down.
2) Sludge from the bottom of the tank is also removed and by breaking down the organic matter in sludge, releases methane gas in the process which can be used as an energy source and the remaining digested water can be used as a fertiliser and is broken down by the bacteria in a process called anaerobic digestion.

4) Final treatment: The treated wastewater is safe enough to be discharged back into rivers.
5) Wastewaters containing toxic substances cannot be put in the river as it is too sensitive therefore water is sterilised by UV light or by chlorine.

Question 23

Define

• effluent
• slurry
• grit
• sludge

Answer 23

• effluent- liquid waste which has been discharged into seas or river and solid organic matter is removed.
• slurry: semi liquid- liquid with a solid in it eg manure or coal suspended in the liquid
• grit- small rocks and salt.
• sludge- more viscous and has less water- thick mud.

Question 24

How can you treat the sewage sludge?(3)

Answer 24

• most can be dried and used as fertiliser or farmland to improve the soil or used as a renewable source of energy.
• can be turned into a ‘crusty solid cake’ which can be used to burn electricity.
• when sewage sludge is dried, it takes up a lot less space and becomes easier to take it away the sewage treatment plant

Question 25

Benefits of treating waste water vs distillation?(4)

Answer 25

• Cost effective.
• Could provide potable water directly.
• Dried treated solid can be used as fertiliser.
• Treatment of waste water produces methane- a renewable fuel.

Question 26

What is a life cycle assessment? What stages are involved(4)

Answer 26

A life-cycle assessment or LCA is a ‘cradle to grave’ analysis of the impact of a manufactured product on the environment. There are many detailed stages but the main ones are:
• 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 27

How does raw materials and manufacture affect LCA?

Answer 27

1. Raw materials
   All the raw materials we need come from the Earth’s crust, atmosphere or oceans, or are due to living organisms. Obtaining these materials has an impact on the environment, including:

• using up limited resources such as ores and crude oil
• damaging habitats through quarrying, mining, or felling trees

2. Manufacture
   The manufacture of products has an impact on the environment, including:

• using up land for factories
• the use of machines and people

Question 28

How does use and disposal affect LCA?

Answer 28

3. Use
   The impact of a product on the environment during its use depends on the type product. For example, a wooden chair has very little impact, unless it needs cleaning or repair. On the other hand, using a car will have a significant impact.
4. Disposal
   The disposal of old products has an impact on the environment, including:

• using up land for landfill sites
• whether any or all of the product can be recycled or reused

Question 29

Give LCA comparisons between plastic bags and paper bags in regards to the raw material and manufacture?

Answer 29

Plastic bags:

1) Raw material:
- Crude oil is a finite resource; fractional distillation, cracking and polymerisation all require a lot of energy.

2) Manufacturer:
- Cheaper to make large quantities of bags from plastic.

Paper bags:

1) RM:
- Can be made from recycled paper, or from trees. Making paper from trees requires more energy than recycling paper, but much less than making plastics..
- Making paper also requires a huge amount of water.

2) M
- More expensive to make bags from the paper because the handles must be glued on.
- Not strong and can tear.

Question 30

Give LCA comparisons between plastic bags and paper bags in regards to the use and the disposal.

Answer 30

Plastic Bags.

1) Use : Lower impact on the environment because plastic bags are usually stronger so they can be reused many times.
- Relatively short lifetime; can only be reused a limited number of times.

2)Disposal: Can sometimes be collected and recycled; if disposed of as litter, they do not biodegrade; in landfill, may take decades or centuries to degrade.

Paper Bags:

1) Use: Relatively short lifetime; can only be reused a limited number of times.
2) Disposal: Can be recycled easily; if disposed of in landfill, they biodegrade quickly.

Both plastic bags and paper bags have to be transported to landfills or for recycling. Paper bags are heavier so they can take more energy to transport.

Question 31

Is LCA a purely objective process? (2)

Answer 31

• Use of water, resources, energy sources and production of some wastes can be fairly easily quantified.
• However, we cannot always be sure as to how they are damaging to the environment as allocating numerical values to pollutant effects is less straightforward and requires value judgements or estimate values, so LCA is not a purely objective process.

Question 32

Problems with LCA?

Answer 32

1) Can be biased eg to support claims by advertisers as producing an LCA is not an objective method and takes into account the values of the person carrying out the assessment.
2) Selective LCAS, which only show some of the impacts of a product on the environment can also be biased as they can be written to deliberately support the claims of a company, in order to give them positive advertising.

Question 33

How are most copper extracted from and why is this process not sustainable?

Answer 33

Most copper is extracted from copper- rich ores and they are a finite resource and have a danger of running out as they are in a short supply.

Question 34

Extracting Copper from malachite PAG?

with ionic eqs.

Answer 34

1) Malachite is a copper ore containing copper carbonate and to extract the copper, thermal decomposition occurs and copper oxide is left in the tube and CO2 is left behind.
2) add dilute sulphuric acid to the copper oxide to form a copper sulphate solution
3) Put an iron nail into the copper sulphate solution and the iron is more reactive than copper so it will displace it to form iron sulphate + copper.
Fe-> Fe2+ + 2e-
Cu2+ + 2e- = Cu

Overall eq= Fe + Cu2+ -> Fe2+ + Cu

4) or collect some extra copper sulphate solution and place it in a beaker. Set it up in an electrolysis with carbon electrodes and the copper metal will be deposit at the negative electrode as it reduced.

Cu2+ 2e- -> Cu.

Question 35

What are some other ways to improve the sustainability of extracting copper? (2)

How do these methods compare with traditional methods?

Answer 35

1) Bioleaching- bacteria are used to convert copper compounds in the ore into soluble copper compounds, separating out the copper from the ore in the process. The leachate( the solution produced by the process) contains copper ions, which can be extracted by electrolysis or displacement with a more reactive metal such as scrap iron.

About 20% of the copper comes from bioleaching but it is a slow process.

2) Phytomining- this involves growing plants in soil that contain low grade copper. ore The plants can’t use or get rid of the copper so it gradually builds up in leaves. The plants can be harvested, dried and burned in a furnace. The ash contains soluble copper compounds from which copper can be extracted by adding sulphuric acid. This made a leachate of copper sulphate and by electrolysis or displacement using scrap iron, pure copper metal can be extracted,

Traditional methods of copper mining and pretty damaging to the environment and these new methods of extraction have a much smaller impact but the disadvantage is that they’re slow.

Question 36

What is one way to reduce our need for copper rich ores? Elaborate on the given answer (5)

How are metals usually recycled?

Answer 36

• Recycling.
• Mining and extracting metals take lots of energy, most of which comes from burning fossil fuels.
• Recycling metals often uses much less energy than is needed to mine and extract new metal, conserving the finite amount of each metal in the earth and cuts down on the amount of waste getting sent to landfills.
• Metals are usually recycled by melting them and then casting them into the shape of the new product.
• The amount of separation required for recycling materials can change.

Question 37

Why is recycling key? (3)

Answer 37

to reduce:

• our use of limited resources.
• our use of energy.
• the waste we produce.

Question 38

Give a few points on recycling:

1) aluminium
2) iron and steel.

Answer 38

• aluminium is extracted from molten aluminium oxide which requires electrolysis and is very expensive and requires lots of energy generated from the burning of fossil fuels, therefore, recycling helps reduce energy.
• iron and steel
• a blast furnace is used to extract iron from its ore at high temp using carbon- problems with pollution arrise when fossil fuels are burnt so using less energy helps reduce these effects.

Question 39

Can glass be recycled?(4)

Answer 39

• glass recycling can help sustainability by reducing the amount of energy to make new glass products and also the amount of waste created when used glass is thrown away
• glass bottles can often be reused without reshaping.
• Glass bottles can be crushed and melted to make different glass products such as bottles or jars and might also be used for a diff purpose such as insulating glass wool for wall insulation in homes.
• Other products cannot be reused and so are recycled for a different use. Usually, the glass is separated by colour and chemical composition before being recycled.

Question 40

Evaluate the recycling with environmental considerations? (4)

Answer 40

• recycling reduces the need to mine the ores and conserves the Earth’s limited resources
• prevents any pollution that arises from extracting the metal from its ore= reduces the burning of fossil fuels.
• noise and dust pollution and destroys the habitats of animals and organisms and recycling reduces this.
• when ores are mined, they must be processed to extract the metals and they release pollutants such as sulphur dioxide which causes acid rain and co2 contributes to global warming and enhances greenhouse gases.

Question 41

What is corrosion vs rusting?(5)

Answer 41

Corrosion is where metals react with substances in their environment and are gradually destroyed.

• iron corrodes easily and it is called rusting and this is only appropriate for iron and not any other metals.
• For iron to ruse, iron needs to be in contact with both O2 and water.
• iron+ oxygen + water -> hydrated iron (III) oxide and corrosion only happen on the surface of a material where it’s exposed to the air.
• rust is a soft crumbly solid that soon flakes off to leave more iron available to rust again

Question 42

How can you test as to what causes the iron rust?

Answer 42

1) Put an iron nail in a boiling tube with water, it won’t rust as the water is boiled to remove oxygen and oil is used to stop the air getting in.
2) 2nd testube- put an iron nail in a boiling tube with air, it won’t rust as calcium chloride can be used to absorb any water from the air.
3) 3rd testtube- put an iron nail in a boiling tube with air and water, it will rust and to test if a material has rusted, the mass of a rusty nail will increase as the iron atoms in the nail have now bonded to oxygen and water molecules, resulting in a compound that is heavier than iron alone.

Question 43

How does alumminium corrode? (2)

Answer 43

• corrodes when exposed to air.
• unlike iron objects, things made from alum aren’t completetly destriyed by corrsion- alumminium oxide is a protective layer which is v unreactive that forms when aluminium corrodes doesn’t flaske away and it sticks firmly to the alumminium below and stops any furthe reaction taking place.

Question 44

How are there ways to prevent rusting? (3)

Answer 44

1) Coat the iron with a barrier to keep out H20 and O2:
- painting/ coating with plastic- ideal for big and small structures alike.
- electropainting- uses electrolysis to reduce metal ions onto an iron electrode and can be used to coat the idron with a layer of a different metal that won’t be corroded away.
- oiling/ greasing- when moving parts are involved, like on bike chains.

2) Sacrificial methhods- placing a more reactive metal such as zinc or magnesiu with the iron. Water and oxygen then react with the sacrifical metal instead with the iron.
3) An object can be galvanished by spraying it with a coating of zinc. The zinc layer is firstly protective but if its sccratched, the zinc around the site of the scratch works as sacrifical metal and as as it is more reactive, it would be oxidised in preference to Fe.

Question 45

What is the problem with galvanisation?

Answer 45

1) Needs to be replaced.

2) Cost a lot of money.

Question 46

When is sacrificial ways usually used? (3)

Answer 46

• used under harsh conditions such as when the iron is in contact with seawater, as salt accelerates rusting.
• but sacrificial metrals will need replacing.
• sacrifical protetion is used when the metal coating is likely to be scratched off

Question 47

What happens to the ammonia after the Haber process?(4)

Answer 47

• After the haber process, 10% of the ammonia is converted in another process into nitric acid.
• then the ammonia can react with the nitric acid to make ammonium nitrate fertiliser.
• NH3 + HNO3 -> NH4NO3
• Ammonia can also be neutralised by sulphuric acid to make ammonium sulphate fertiliser, and with phosphoric acid to make ammonium phosphate fertiliser.

Question 48

What are NPK fertilisers? (3)

Answer 48

• Compounds of nitrogen, phosphorus and potassium are used as fertilisers to improve agricultural productivity. NPK fertilisers contain compounds of all three elements in the right %s and these elements may be missing from the soil if they’d been used up by a previous crop.
• Fertilisers help increase crop yield as the crops grow faster and bigger eg fertilisers contain nitrogen to make proteins which makes the plant grow faster- increasing productivity.
• Industrial production of NPK fertilisers can be achieved using a variety of raw materials in several integrated processes.

NPK fertilisers are formulations of various salts containing appropriate percentages of the elements.

Question 49

What is the source for phosphorous?

Answer 49

The sources of phosphorous are deposits of phosphate-containing rock, which is dug or mined from the ground.
- It cannot be used directly on the soil as it is insoluble in water, so the rock is treated with acid to make fertiliser salts.

Question 50

Explain why desalination is not needed to produce large quantities of water in the UK (2)

Answer 50

1) Uses large amounts of energy

2) We have enough fresh water sources

Question 51

Name one factor, apart from yield, that must be taken into consideration when choosing the temperature and pressure to operate the Haber process plant at?

Answer 51

Cost, safety, rate

Question 52

Why are alloys harder than pure metals?

Answer 52

Because the regular layers in a pure metal are distorted by differently sized metal atoms in an alloy which prevents layers from sliding over each other.

Question 53

How are steel made?

Answer 53

-carefully controlled quantities of carbon and other elements are added to iron to make steel alloys with diff properties

Question 54

list %, property and use

• low carbon steel.
• high carbon steel.
• stainless steel

Answer 54

• low carbon steel- 0.1-0.3%- easily shaped- car bodies.
• high carbon steel- 0.22-2.5%- v strong, inflexible and resistant to stretching forces, brittle- bridges.
• stainless steel- chromium added and sometimes nickel- corrosion resistant so don’t rust, hard- cutlery and cooking utensils

Question 55

How is:
-bronze
-brass
made?

Answer 55

1) Bronze= copper + tin.
- Bronze is harder than copper and it’s used to make medals, decorative ornaments and statues.
2) Brass= copper + zinc
- more malleable than bronze and is used in situations where lower friction is required, such as in water taps and door fittings, musical instruments such as trumpets

Question 56

What are gold alloys used to make?

Alumminum alloys?

Answer 56

1) Gold alloys are used to make jewellery as pure gold is v soft and metals such as zinc copper and silver are used to harden the gold. Pure gold is described as 24 carats. Pure gold wears away easily than its alloy with copper and by varying the proportions of the 2 metals, it is possible to get different shades of ‘gold’ objects
2) Aluminium alloys are used to make aircraft but AL has a low density which is impo for the aircraft manufacturer, military vehicles,but pure alum is too soft for making aeroplanes so it’s alloyed with small amounts of other metals to make it hard

Question 57

How much gold is in 18 carats?

Answer 57

18/24 75% gold

Question 58

What are most modern materials made up of? what do people have to keep in mind?

Evaluate the effects of mining. 2 adv and 4 disadv

Answer 58

1) Many modern materials are made from raw, finite resources for eg most plastics, metals and building materials.
2) People have to balance the social, economic, environmental effects of extracting finite resources.

3) Eg mining metal ores is good because useful products can be ,ade and it also provides local people with jobs and brings money into the area however mining ores is bad for the environ as it uses loads of energy, most of which comes from the burning of fossil fuels, scars the landscape, produces lots of waste and destroys habitats.

Question 59

Glass bottles can be reused, whereas metal is recycled- describe the similarities and differences between these two processes? (3)

Answer 59

Both glass and metals are melted (1)
Glass is crushed before melting(1)
whereas metals are recasted/ reformed after melting (1)

Question 60

List what:
- high carbon steel(3)
- low carbon steel
can be used for?

Answer 60

High carbon steel: tools, cutters, bridges.

Low carbon steel- construction/ building/ ships vehicles.

Question 61

Give a source for nitrogen and hydrogen?

Answer 61

Nitrogen- air

Hydrogen- natural gas

Question 62

Describe what happens in the aeration chamber?

Answer 62

Microbes break down dissolved organic matter by using air.

Question 63

Explain why obtaining potable water from distillation is not good for the environment? (2 marks)

Answer 63

• Requires large amount of energy that could be produced through the use of finite resources such as crude or fossil fuels.
• Co2 and other pollutants are also released which can cause acid rain and global warming

Question 64

Describe a test that could be carried out to show the water produced is pure.

Answer 64

-Measure water at boiling point and it should be 100 degrees

Question 65

Give some reasons as to why scrap iron is used to extract copper rather than more reactive scrap metal such as zinc (3)

Answer 65

• Scrap iron is cheaper.
• More scrap iron is available than zinc.
• Zic react mores vigorously than iron

Question 66

Describe 5 adv and 3 disadv of using bioleaching and phytomining to obtain copper

Answer 66

Adv:

1) Less energy is needed.
2) Uses low grade copper ore.
3) Reduces need for copper rich ores.
4) No release of sulphur dioxide.
5) Phytomining plants release more energy when when burnt.

Disadv:

1) Takes time to grow plant.
2) Impure copper.
3) Large vol of leachate must be disposed of.

Question 67

(2 marks) Why is LCA carried out on products?

Answer 67

-How a manufactured product affects the environment over time and how damaging it may be from the extraction of raw materials to its disposal

Question 68

Give 5 possible methods of reducing the carbon footprint of a plastic bottle.

Answer 68

1) Recycle.
2) Increased use of alternate energy.
3) Reduce energy consumption.
4) CCS.
5) Carbon offsetting- reduce through tree planting