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PAPER 2 : CHEMISTRY > C10 > Flashcards

C10 Flashcards

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1
Q

Give examples of natural resources and how they are used

A
  • wood (timber)
  • farming
  • fuels
  • rubber
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2
Q

Give details of a natural resource which has been replaced by a synthetic product

A

rubber

  • all rubber used to be extracted by ‘tapping’ rubber trees
  • however, chemist are developing synthetic polymer (long chain molecules)
  • to use for products traditionally made from rubber
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3
Q

Give details of a resource which has been supplemented by a synthetic product

A

it would be fertilisers for agricultural

  • dung used to be used as a natural fertiliser
  • using man made fertilisers to increase the crop yield
  • is an example of using synthetic products to supplement a natural resource
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4
Q

Describe the difference between finite and renewable resources (with examples)

A
  • finite resources will run out and can not be replaced/reused
  • however renewable resources you can reuse it
  • example of finite resource are: quarry’s, coal, crude oil
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5
Q

What is ‘sustainable development’? Give an example

A
  • development which meets the needs of people alive today
  • without compromising the ability of future generation to meet their own needs
  • example of this would be: limiting the number of fish allowed in a catch( ‘a quota’)
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6
Q

What is potable water? How is this different to pure water?

A
  • potable water is drinkable, safe water
  • however it’s not pure as it contains dissolved substances but it’s still safe to drink as the quantities of substances are low
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7
Q

Describe the three steps we can use to provide potable water in the UK. Make sure to explain why we do each step

A

1) choose an appropriate source
= as the water supply should be dirty not clean/safe water or sea water (as seawater cost & take alot of time to desalinate it)

2) pass the water through a filter bed
= so that any waste, rubbish, dead bacteria can be trapped in the filter bed to separate it from the water

3) sterilize it with chlorine, ozone gas or UV light
= so that it kills (NOT REMOVE) the bacteria from the bacterial water

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8
Q

Other countries do not have the same amount for fresh water supplies as we do, so they have to use other methods to obtain potable water
State the names of 2 of the methods:

A
  • desalination by distillation

- reverse osmosis

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9
Q

Use the step to describe the process of distillation. Use the key words boil and condense

A
  • a rounded bottom flask will contain salty water which is heated by as bunsen burner
  • this is then turned into pure water vapour once it boils at around 105o as the water is not pure
  • the vapour then travels up the flask to the spring which cools water out
  • it also condenses in the condenser from the vapour
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10
Q

What happens during the process of reverse osmosis?

A

is when a membrane is used to filter out bacteria

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11
Q

If a country had access to both freshwater and saltwater supplies, from which would they obtain their drinking water. Explain my answer

A

both methods use a lot of energy and are expensive

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12
Q

State a range of sources of waste water?

A
  • sewage
  • industrial waste water
  • farming/agricultural
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13
Q

Why is it important to treat the waste water from sewage and agricultural?

A
  • requires treatment before being returned to the environment
  • both to remove organic matter & any harmful microbes
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14
Q

How many stages are there to treat sewage?

A

4 stages

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15
Q

Explain stage 1 in sewage treatment

A

stage 1 is screening

  • to remove any larger bits of material (like bags or plastic) and any grit (small bits of stone & sand)
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16
Q

Explain stage 2 in sewage treatment

A

stage 2 is sedimentation

  • allowing the heavier solids sink to the bottom to produce sludge
  • the lighter effluent (liquid waste) floats on the top
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17
Q

Explain stage 3 in sewage treatment

A

stage 3 is treating effluent

  • is removed and treated by biological aerobic digestion
  • this is where bacteria breaks down any organic matter - including other microbes in the water then clean water plumbs back in rivers
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18
Q

Explain stage 4 in sewage treatment

A

stage 4 is breaking down sludge

  • is also broken down by bacteria in a process called anaerobic digestion
  • this produces methane gas which can be used as an energy source
  • the remaining waste can be used as fertilisers
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19
Q

State the names of the 4 methods to obtain potable water

A
  • treating fresh water
  • desalination
  • reverse osmosis
  • treating sewage
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20
Q

How do we extract gold?

A

it can be mined in its pure form

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21
Q

How do we extract iron?

A

we heat with carbon which reduces the ore in a displacement reaction

22
Q

How do we extract aluminum?

A

electrolysis

23
Q

What issues are there with traditional extraction methods?

A
  • have to dig, move and dispose of a large amount of rock
  • extraction requires heavy machinery, releasing a lot of greenhouse gases (CO2 and SO2) into the atmosphere
  • quarrying causes environmental issues, eg. reduction in land availability, habitat loss and reduced biodiversity
  • high-grade metal ore is also a finite resource which we are running out of
24
Q

What is a metal ore?

A

a rock which contains enough metal to make it economical to extract it

25
Q

What is low-grade ore?

A

ores containing a small amount of copper

26
Q

Why are low grade ores less desirable than high grade?

A

harder to extract metal economically from low grade ores (won’t make as much money)

27
Q

What organisms are used in phytomining?

A

plants

28
Q

Where are the plants grown?

A

in soil which contains the metal compound we want

29
Q

What happens to the metal compounds in the soil?

A

the plants absorb the metal compound and it becomes concentrated in the plant tissue

30
Q

How are the metal compounds extracted from the plant?

A

the plants are harvested and burned to collect the ash

31
Q

What organisms are used in bioleaching?

A

bacteria

32
Q

How does bioleaching work?

A

bacteria is mixed with the ore and carries out chemical reactions to produce a solution called a leachate

33
Q

What does the leachate contain?

A

the metal compound we want

34
Q

How can the metal be extracted from the copper compounds collected by these 2 methods? (2 possibilities)

A
  • displace using iron (for less reactive metals)

- electrolysis (more reactive metals)

35
Q

Why is scrap iron used in the first method?

A

it is cheap and readily available

36
Q

Give the main advantage of both bioleaching and phytomining

A

they allow us to extract metal from low grade ores

37
Q

Why is this so important?

A

metal is a finite resource (it will run out)

38
Q

Give another advantage of both bioleaching and phytomining

A
  • rock does not have to be dug up, transported and disposed of like it does in traditional mining
  • which means there is less environmental impact
39
Q

Can you think of any disadvantages of these methods?

A

Both:

  • produces smaller amounts of copper
  • takes a long time (either for the bacteria to produce the solution or the plant to grow)

Phytomining:

  • takes up a lot of space
  • produces carbon dioxide when plants burnt
  • land cannot be used to grow food crops

Bioleaching:
- can produce toxic substances like sulfuric acid

40
Q

Why are these (LCA’S) carried out?

A

to assess the environmental impact of products at each of these stages

41
Q

What are the 4 stages which are considered in a Life Cycle Assessment?

A

1) raw materials
2) manufacturing
3) use
4) disposal

42
Q

What steps are involved in its life cycle?

A

steps in the bag’s life cycle:

1) drill for crude oil
2) put the oil through fractional distillation
3) crack alkanes to make ethene
4) use heat to polymerise ethene
5) transport plastic bags to shops
6) transport bags to landfill sites

43
Q

How can the carbon footprint of each step be reduced?

A

ways to reduce the pollution or environmental cost:

1) use recycled materials
2) reduce consumption of the bags
3) manufacture them closer to shops
4) recycle the bags after use

44
Q

Describe the LCA stage of plastic bag

A

Raw material :
-crude oil

Manufacturing(and packaging) :

  • plastic are made from compounds extracted from crude oil by fractional distillation & processed by cracking & polymerisation
  • waste is reduced as the other fractions of crude oil have other use

Using the product :

  • can be reused serval times
  • can be used for other things as well as shopping (for examples as bin liners)

Product disposal :
- recyclable but not biodegradable and will take up space in landfill & pollute land

45
Q

Describe the LCA stage of paper bag

A

Raw material :
- trees/ wood

Manufacturing(and packaging) :
- pulped wood and processed using lots of energy but also lots of waste is made

Using the product :
- usually only used once

Product disposal :
- biodegradable, non-toxic and can be recycled

46
Q

Explain the problems with Life Cycle Assessments

A
  • the use of energy, some natural resources and the amount of certain types of waste produced by a product over it’s lifetime can easily quantified . However the effect of some pollutants is harder to give a numerical value (e.g: it’s difficult to apply a value to the negative visual effects of plastic bags in the environment compared to paper one)
  • LCA’s is not an objective method as it takes into account the values of the person carrying out the assessment. meaning LCA’s can be biased
  • selective LCA’s only show some of the impacts of a product on the environment can be also biased as they can be written to deliberately support the claims of a company to give them positive advertising
47
Q

Why is it important to recycle materials?

A

1) less space will be needed for landfill sites if there is less waste
2) recycling uses far less energy compared to producing new materials
3) recycling saves raw materials - metal, plastics, glass & ceramics all comes from limited raw material
4) less excavation (digging up) & mining costs. plus less environmental damage from these activities

48
Q

Give examples of resources which are produced from limited raw materials

A

metals , plastics, ceramic

49
Q

What issues are there with obtaining and processing these raw materials?

A

many of the energy for the processes come from

50
Q

How can glass be recycled?

A
  • glass bottles can be crushed and melted to make other glass products
51
Q

How can metal be recycled?

A
  • metals can be recycled by melting and recasting into different products
  • sometimes a substitute can be used, e.g. some scrap steel can be added to iron to reduce the amount of iron needed

PAPER 2 : CHEMISTRY (3 decks)

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