Using the Earth's Resources

Question 1

what has chemistry replace natural resources with?

Answer 1

a synthetic alternative

Question 2

an example of a synthetic alternative?

Answer 2

rubber

Question 3

where does natural rubber come from?

Answer 3

the sap of a tree

Question 4

how is synthetic rubber produced?

Answer 4

using crude oil

Question 5

examples of finite resources?

Answer 5

• fossil fuels
• metal

Question 6

example of renewable resources?

Answer 6

wood

Question 7

why is it important that human activities are sustainable?

Answer 7

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

Question 8

what do artificial fertilisers do?

Answer 8

they allow us to grow more food with the land available

Question 9

define potable water

Answer 9

water that is safe to drink

Question 10

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

Answer 10

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

Question 11

how is potable water produced? (3)

Answer 11

• 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

Question 12

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

Answer 12

through desalination

Question 13

what is desalination?

Answer 13

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

Question 14

two ways of carrying out desalination

Answer 14

1. distillation
2. reverse osmosis

Question 15

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

Answer 15

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

Question 16

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

Answer 16

• 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

Question 17

what is the easiest way to produce potable water?

Answer 17

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

Question 18

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

Answer 18

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

Question 19

describe the process of desalination (4)

Answer 19

• 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.

Question 20

why is desalination expensive?

Answer 20

because it requires a lot of energy

Question 21

state the three ways that water can be sterilised

Answer 21

• adding chlorine
• adding ozone
• adding UV (ultraviolet light)

Question 22

metal extraction is by: (2)

Answer 22

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

Question 23

define low-grade ore

Answer 23

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

Question 24

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

Answer 24

because copper ores are starting to become scarce

Question 25

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

Answer 25

- phytomining - bioleaching

Question 26

define **phytomining**

Answer 26

the extraction of copper using plants

Question 27

define **bioleaching**

Answer 27

the extraction of copper using bacteria

Question 28

describe the process for **phytomining** (3)

Answer 28

- 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

Question 29

describe the process for **bioleaching** (3)

Answer 29

- the bacteria absorb the copper compounds - they produce a leachate solution containing copper - this leachate is then processed to remove the copper

Question 30

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

Answer 30

ADVANTAGES - removes carbon dioxide via photosynthesis - extracts copper from where there is limited resources DISADVANTAGES - burning releases carbon dioxide into the atmosphere

Question 31

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

Answer 31

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

Question 32

define what is meant by **life-cycle assessment**

Answer 32

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

Question 33

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

Answer 33

- extraction and process of raw materials - manufacturing and packaging - use and reuse - disposal

Question 34

how are plastic bags produced?

Answer 34

using chemicals from crude oil

Question 35

how are paper bags produced?

Answer 35

using wood from trees

Question 36

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

Answer 36

- 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

Question 37

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

Answer 37

- 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

Question 38

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

Answer 38

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

Question 39

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

Answer 39

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