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Chemistry Paper 2 > Using the Earth's Resources > Flashcards

Using the Earth's Resources Flashcards

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1
Q

what has chemistry replace natural resources with?

A

a synthetic alternative

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2
Q

an example of a synthetic alternative?

A

rubber

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3
Q

where does natural rubber come from?

A

the sap of a tree

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4
Q

how is synthetic rubber produced?

A

using crude oil

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5
Q

examples of finite resources?

A
  • fossil fuels
  • metal
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6
Q

example of renewable resources?

A

wood

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7
Q

why is it important that human activities are sustainable?

A

so that we can meet our needs without preventing future generations from meeting theirs

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8
Q

what do artificial fertilisers do?

A

they allow us to grow more food with the land available

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9
Q

define potable water

A

water that is safe to drink

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10
Q

what’s the difference between potable water and pure water?

A
  • pure water doesn’t contain any dissolved substances at all whilst potable water does contain dissolved substances
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11
Q

how is potable water produced? (3)

A
  • choose a good source of fresh water
    e.g lake or reservoir
  • pass the water through filter beds to remove leaves and suspended particles
  • the water is then sterilised to kill microbes; in the uk, we use chlorine to sterilise potable water
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12
Q

how is potable water produced in countries that don’t have many sources of fresh water?

A

through desalination

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13
Q

what is desalination?

A

reduces the levels of dissolved minerals down to an acceptable level for potable water

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14
Q

two ways of carrying out desalination

A
  1. distillation
  2. reverse osmosis
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15
Q

why must waste water be carefully treated before going back into the environment? (2)

A
  • because it contains a very large amount of organic molecules
    e.g from urine or faeces
  • it also contains harmful microorganisms such as bacteria
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16
Q

what is the method in which waste water is treated? (7)

A
  • in the first stage, the sewage is screened by passing through a mesh; this removes solids and pieces of grit
  • then, the sewage is allowed to settle in large sedimentation tanks; this produces a liquid effluent and a semi-solid sludge which sinks
  • the liquid effluent has air bubbled through it which allows aerobic bacteria to multiply
  • the aerobic bacteria digest the organic molecules and harmful microorganisms
  • after this, the liquid effluent can be safely discharged into a nearby river
  • this sludge is then taken away and digested by anaerobic bacteria
  • at the end, the digested sludge can be used as fertilisers for farming
17
Q

what is the easiest way to produce potable water?

A

by using ground water from aquifers
- this is usually safe to drink, once it’s been
treated with chlorine

18
Q

why would the water from aquifers need to be tested carefully?

A

because it can sometimes be polluted with things like fertilisers from farms

19
Q

describe the process of desalination (4)

A
  • pressure is applied to sea or salt water
  • water molecules are forced over a partially permeable membrane
  • salt molecules within the water are too big to pass through the membrane
  • after the molecules of water have passed through the membrane, fresh water is created.
20
Q

why is desalination expensive?

A

because it requires a lot of energy

21
Q

state the three ways that water can be sterilised

A
  • adding chlorine
  • adding ozone
  • adding UV (ultraviolet light)
22
Q

metal extraction is by: (2)

A
  1. reduction with carbon
    • carbon removes impurities like the oxygen
      from the metal ore
  2. electrolysis
    • an electric current separates the ions in
      the ore to be left with a pure metal
23
Q

define low-grade ore

A

ores that contain limited copper/only a very small amount of copper

24
Q

why is copper now having to be produced from low-grade ores?

A

because copper ores are starting to become scarce

25
Q

name the two methods in which copper is extracted from low-grade ores:

A
  • phytomining
  • bioleaching
26
Q

define phytomining

A

the extraction of copper using plants

27
Q

define bioleaching

A

the extraction of copper using bacteria

28
Q

describe the process for phytomining (3)

A
  • plants are burnt
  • when this happens, the copper ions combine with oxygen to form copper compounds in the left over ash
  • electrolysis is then used to purify the copper compounds
29
Q

describe the process for bioleaching (3)

A
  • the bacteria absorb the copper compounds
  • they produce a leachate solution containing copper
  • this leachate is then processed to remove the copper
30
Q

what are the advantages (2) and disadvantages (1) of phytomining?

A

ADVANTAGES
- removes carbon dioxide via photosynthesis
- extracts copper from where there is limited resources

DISADVANTAGES
- burning releases carbon dioxide into the atmosphere

31
Q

what are the advantages (3) and disadvantages (3) of bioleaching?

A

ADVANTAGES
- naturally occurring process
- reduces sulfuric acid from being released into the soil
- extracts from low grade-ores (where there’s little resources)

DISADVANTAGES
- costly; requires energy
- still needs electrolysis
- lengthy process

32
Q

define what is meant by life-cycle assessment

A

looking at the environmental impact at each stage in a products life

33
Q

what are the four main stages that need to be looked at when carrying out a life-cycle assessment?

A
  • extraction and process of raw materials
  • manufacturing and packaging
  • use and reuse
  • disposal
34
Q

how are plastic bags produced?

A

using chemicals from crude oil

35
Q

how are paper bags produced?

A

using wood from trees

36
Q

name the disadvantages in the process of producing plastic bags? (2)

A
  • extracting crude oil can be harmful to habitats if there’s an oil leak
  • needs to be chemically processed which requires a lot of energy and releases waste products
37
Q

name the disadvantages in the process of producing paper bags (3)

A
  • felling trees for food is extremely destructive to habitats
  • need to be chemically processed with requires a lot of energy and releases waste products
  • making the paper requires large amounts of water
38
Q

describe the differences between the use and reuse of paper and plastic bags: (4)

A

PAPER
- not very strong and tend to tear
- they’re often used once before being thrown away

PLASTIC
- plastic shopping bags are relatively strong
- they are often reused

39
Q

describe the differences between the disposal of paper and plastic bags:

A

PAPER
- breaks down quickly, especially when wet

PLASTIC
- non biodegradable, meaning they can’t be broken down by microorganisms, and so they stay in the environment for a long time

Chemistry Paper 2 (4 decks)

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