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chemistry > using resources (paper 2) > Flashcards

using resources (paper 2) Flashcards

1
Q

what is potable water

A

water of a suitable quality is essential for life

for humans water should have sufficiently low amounts of dissolved salts and microbes

water that is safe to drink is potable water

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2
Q

what are the stages of producing potable water

A

1 - filtration - leaves, stones and large material is removed

2 - water moves through and any sediment settles at the bottom of the tank

3 - add aluminum sulphate which makes it clump together and sink to the bottom of the tank

4 - water is passed through fine sand and gravel to remove more particles

5 - sterilisation the water is sterilised with chlorine or UV light

6 - pH is checked and adjusted if needed

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3
Q

what is the method for purifying salty water through distillation

A

salty water is heated and then evaporated and condensed

creates pure fresh water

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4
Q

what is the method for purifying salty water through reverse osmosis

A

using high pressure , salty water is forced through a semi permeable membrane

the salt is removed and the water moved through

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5
Q

what is the method for treating sewage water

A
  1. large objects are filtered from the water
  2. large paddles swirl the water and solids sink and are collected at the bottom
  3. bacteria feed aerobically on organic matter and kill harmful bacteria and good bacteria are removed during secondary sedimentation
  4. the water is sterilised using chlorine, ozone or UV light
  5. sludge is digested in a bio gas tank and becomes fertiliser, bio gas etc and can be used to generate electricity
  6. water is pumped into seas and rivers
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6
Q

what is sludge from a biogas tank used to make

A

fertiliser

biogas

solid fuel

can be used to generate electricity

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7
Q

what is an LCA

A

life cycle assessments

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8
Q

why are LCA’s carried out

A

to assess the environmental impacts of a product through all stages of its life

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9
Q

what are the stages of LCA’s

A
  1. raw materials
  2. manufacture
  3. distribution
  4. product use
  5. disposal of the product
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10
Q

what are the raw materials of paper bags and plastic bags

A

plastic bag - crude oil

paper bag - timber

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11
Q

what is the manufacturing and packaging of plastic bags and paper bags

A

plastic bag - the compounds needed to make the plastic are extracted from crude oil by fractional distillation, followed by cracking and then polymerisation. waste is reduced as the other fractions of crude oil have other uses

paper bag - pulped timber is processed using a lot of energy , lots of waste is made

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11
Q

what are the uses of the products of plastic bags and paper bags

A

plastic bag - can be reused. can be used for other things as well shopping e.g. bin liners

paper bag - usually only used once

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12
Q

what is the product disposal of a plastic bag and a paper bag

A

plastic bag - recyclable but not biodegradable and will take up space in land fill and pollute land

paper bag - biodegradable, non toxic and can be recycled

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13
Q

why is an LCA not an objective method

A

it takes into account the values of the person carrying out the assessment, which means they can be biased

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14
Q

how can selective LCAs be biased

A

they only show some of the impacts of a product on the environment, and they can be written to deliberately support the claims of a company in order to give them positive advertising

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15
Q

what is needed to make ammonia

A

nitrogen and hydrogen

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16
Q

symbol equation for the Haber process

A

N2 + 3H2 REVERSIBLE SIGN 2NH3

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17
Q

industrial conditions

A

pressure = 200 atmospheres

temperature = 450 degrees celcius

catalyst = iron

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18
Q

where is nitrogen obtained from in the Haber process

A

easily from the air , which is 78% nitrogen

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19
Q

where is hydrogen obtained from in the Haber process

A

from reacting methane (from natural gas) with steam to form hydrogen and carbon dioxide

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20
Q

what happens due to the Haber process reaction being reversible

A

some of the ammonia produced converts back into hydrogen and nitrogen again and it eventually reaches a dynamic equilibrium

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21
Q

what state is the ammonia made in the Haber process

A

the ammonia formed as a gas , but as it cools in the condenser it liquefies and is removed

the unused hydrogen and nitrogen are recycled so nothing is wasted

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22
Q

what is the ammonia produced in the Haber process used for

A

ammonium nitrate - a very rich nitrogen fertiliser

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23
Q

what ratio are the nitrogen and hydrogen mixed in during the Haber process

A

3 parts hydrogen to 1 part nitrogen

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24
Q

what is the forward reaction of the Haber process

A

exothermic

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25
Q

what happens if we increase the temperature during the Haber process

A

the equilibrium will move backwards - away from ammonia and towards the nitrogen and hydrogen

so the yield of ammonia would be greater at lower temperatures

26
Q

what is the problem with lower temperatures during the Haber process

A

it means a slower rate of reaction - so equilibrium is reached more slowly

27
Q

why is temperature of 450 degrees celcius used during the Haber process

A

it is a compromise between maximum yield and speed of reaction it is better to just wait 20 seconds for a 10% yield than to have to wait 60 seconds for a 20% yield

28
Q

what does a higher pressure cause during the Haber process

A

a higher pressure would move the position of equilibrium towards the products since there are four molecules of gas on the left hand side for every two molecules on the right

so, increasing pressure maximises the percentage yield and also increases the rate of reaction

so the pressure is set as high as possible without making the process too expensive or too dangerous to build and maintain

29
Q

what does the iron catalyst do in the Haber process

A

makes the reaction go faster, but does not affect the yield

30
Q

why are formulated fertilisers so widely used

A

they are more widely available

easier to use

do not smell

have just enough of each nutrient so that more crops can be grown

31
Q

what are the main essentials in a fertiliser

A

nitrogen , phosphorous and potassium

if they do not get enough of these their growth and life processes are affected

these elements may be missing from the soil if they have been used up by previous crops

32
Q

what do fertilisers replace

A

the missing elements from the soil or provide more of them , which helps to increase the crop yield as crops ca grow faster and bigger

33
Q

what are NPK fertilisers

A

formulations containing salts pf nitrogen (N) , phosphorous (P) and potassium (K)

34
Q

what does ammonia , oxygen and water make

A

nitric acid

35
Q

ammonia + acid

A

ammonium salts - which can be used as fertilisers

36
Q

ammonia + nitric acid

A

ammonium nitrate

37
Q

ammonia + nitric acid symbol equation

A

NH3 + HNO3 —> NH4NO3

38
Q

how is ammonium nitrate made in industry

A
  1. the reaction is carried out in giant vats, at high concentrations resulting in very exothermic reactions
  2. the heat released is used to evaporate water from the mixture to make a very concentrated ammonium nitrate product
39
Q

how is ammonium nitrate made in the lab

A
  1. the reaction is carried out on a much smaller scale by titration and crystallisation
  2. the reactants are at a much lower concentration than in industry, so less heat is produced by the reaction and its safer for a person to carry it out
  3. after the titration, the mixture then needs to be crystallised to give pure ammonium nitrate crystals
  4. crystallisation is not used in industry because it is very slow
40
Q

phosphate rock + nitric acid

A

phosphoric acid and calcium nitrate

41
Q

phosphate rock + sulphuric acid

A

calcium sulphate and calcium phosphate

42
Q

phosphate rock + phosphoric acid

A

calcium phosphate

43
Q

properties of clay - ceramics

A

soft material so can be molded into different shapes

when it if fired at high temperatures it hardens to form a clay ceramic

its ability to be molded when wet and then hardened makes clay ideal for making pottery and bricks

44
Q

properties of glass - ceramics

A

generally transparent

can be molded when hot and brittle when thin

45
Q

what is fiberglass made from and what are its uses

A

consists of fibres of glass embedded in a matrix made of polymer

has a low density but is very strong

used for surfboards, skis and boats

46
Q

what is carbon fiber made from and what is it used for

A

have a polymer matrix , the reinforcement is made from either long chains of carbon atoms bonded together or from carbon nanotubes

they are very strong and light so are used in aerospace and sports car manufacturing

47
Q

what is concrete made from and what is it used for

A

made from aggregate embedded in cement

it is very strong

makes it ideal for use in building e.g. skate parks

48
Q

what are composites

A

composites are made from one material embedded in another, fibers or fragments of a material are surrounded by a matrix acting as a binder

49
Q

what are the differences between low density poly(ethene) and high density poly(ethene)

A

low density poly(ethene) is made from ethene at a moderate temperature at a high pressure but high density poly(ethene) is also made from ethene but at a lower temperature and pressure with a catalyst

low density is flexible and used for bags and bottles but high density is more rigid and used for water tanks and drainpipes

50
Q

what properties do polymers have and their uses

A

insulators of heat and electricity

can be flexible and easily molded

polymers are used in clothing and insulators in electrical items

51
Q

what properties do metals have and their uses

A

malleable

good conductors of heat and electricity

ductile, shiny , stiff

uses include in electrical wires, car bodywork and cutlery

52
Q

how is bronze made

A

copper + tin

53
Q

how is brass made

A

copper + zinc

54
Q

why is aluminum used to make air craft parts

A

has a low density

55
Q

what is the word equation for rusting

A

iron + oxygen + water —> hydrated iron (III) oxide

56
Q

how can coating the iron with a barrier prevent rusting - methods

A

painting / coating with plastic

electroplating - uses electrolysis to reduce metal ions onto an iron electrode

oiling / greasing

57
Q

how can the sacrificial method prevent rusting

A

this involves placing a more reactive metal such as zinc or magnesium with the iron

water and oxygen then react with the sacrificial metal instead of with the iron

58
Q

how can an object be galvanised

A

spraying it with a coat of zinc

59
Q

what is a low grade copper ore

A

a rock that has small amounts of copper in it

60
Q

how can copper be extracted using phytomining

A

plants are planted on low grade copper ores , they absorb copper ions from the soil by their roots

the plants are burned which releases carbon dioxide and you are left with plant ash containing copper ions in copper oxide

we then use electrolysis to extract the copper from the copper oxide

this is a slow process but can be sped up by using fast growing plants - it is carbon neutral and a renewable resource

61
Q

how can copper be extracted using bioleaching

A

the bacteria feed on low grade copper ores and produces a leachate

a leachate is a solution that passes through an organism

the leachate contains copper ions - which we then use electrolysis to extract

this is a vey slow process and produces toxic chemicals

62
Q

how can copper be extracted from copper rich ores through the process of smelting

A

heat copper carbonate A LOT so it becomes copper oxide and carbon dioxide

add sulphuric acid to the copper oxide to make copper sulphate solution

displacement reaction -

copper sulphate solution + iron –> iron sulphate + copper

you would see a red brown substance being made or use electrolysis to make copper and oxygen

chemistry (11 decks)

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