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Chemistry > Using resources > Flashcards

Using resources Flashcards

1
Q

what are ceramics

A

non metallic solids with high melting points that are not made from carbon based compounds

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2
Q

what are some general properties of ceramics

A

good insulators of heat and electrify and very brittle and stiff

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3
Q

what are clay ceramics

A

when clay is fired at a high temperature it hardens to form a cay ceramic. Ideal for making pottery and bricks

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4
Q

what are glass ceramics

A

glass can be moulded when hot and brittle when thin.
most glass is a soda lime glass ( made by heating limestone, sand and sodium carbonate until it melts and then it cools to become glass.

borosilicate glass has a higher melting point. its made in the same way as soda lime glass but using sand and boron trioxide

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5
Q

what are composites

A

one material embedded in another. fibres or fragments are surrounded by a matrix which acts as a binder

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6
Q

what are polymers

A

large molecules formed when small molecules ( monomers) join together.
held by strong covalent bonds in long chains
most insulators of heat and electricity and can be flexible
clothing, insulators and electrical items

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7
Q

what are two important things that influence the properties of a polymer

A

the monomers

conditions in which its made

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8
Q

how do the monomers effect the property of a polymer

A

they determine what type of force form between the polymer chains. e.g. if there are cross links or not

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9
Q

what are thermosoftening polymers

A

made of individual tangled chains of polymers. weak forces between the chains which mean they are flexible and can be melted and remoulded.

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10
Q

what are thermosetting polymers

A

cross links between polymer chains so doesn’t melt when heated, it chars instead. They are strong, hard and rigid

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11
Q

how do reaction conditions affect the properties of polymers

A

low density polyethene is made at 200 degrees under hp.

high density polyethene is made at a lower temp and pressure with a catalyst

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12
Q

what are alloys

A

mixtures of two or more metals or a metal and non metal

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13
Q

why do we use a lot of alloys

A

pure metals are often too soft because the layers of atoms slide over each other

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14
Q

why are alloys harder than most metals

A

different elements have different sized atoms so it will distort the layers of the metal atom making it harder for the layers to slide

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15
Q

why is most iron used to make steel

A

too soft and bendy

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16
Q

what is added to iron to make steel

A

carbon and sometimes other metals

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17
Q

give a use for both low carbon and high carbon steel

A

low - car bodies

high- bridges

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18
Q

what is added to make stainless steel

A

chromium and sometimes nickel

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19
Q

bronze

A

idk but i should

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20
Q

brass

A 
alloy of copper and zinc
gold like appearance
more malleable than bronze
good for application which require moving with low friction
e.g. water taps and door fittings
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21
Q

gold alloys

A

used for jewellery cus pure gold is too soft
zinc, copper and silver can be used to harden gold
have slightly different colour to pure gold

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22
Q

aluminium alloys

A

low density
aircrafts
alloyed with small amounts of other metals to make it stronger as its too soft for aeroplanes

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23
Q

what is corrosion

A

when a metal is gradually destroyed by reacting with substances in the environment

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24
Q

what is the equation for iron rusting

A

iron + oxygen + water makes hydrated iron (iii) oxide

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25
Q

when aluminium corrodes, why doesn’t it get completely destroyed

A

the aluminium oxide doesn’t flake away so it leaves a protective layer

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26
Q

how do you experiment rusting

A

nail in boiling tube w water and it wont rust
just air it wont rust
water and air it will rust

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27
Q

how can creating a barrier prevent rust

A

painting a metal or coating w plastic

electroplating uses electrolysis to reduce metal ions onto an iron electrode. can be used to coat iron with a different metal that wont corrode
oiling or greasing

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28
Q

how can the sacrificial method be used to prevent rust

A

put more reactive metal w the one u want to protect so reaction will take place w that one

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29
Q

how is iron galvanized

A

spayed w a coating of zinc

30
Q

what is sustainable development

A

takes account of need of present society while not damaging lives of future generations.

31
Q

what 3 things need to be considered when extracting finite resources

A

social, economic and environmental effects

32
Q

pros of reusing and recycling

A

less energy than required to extract material

33
Q

why do we need new ways of extracting copper

A

supply of copper rich ores is limited
demand is high
traditional methods are expensive for low grade ores

34
Q

how does bio leaching work

A

bacteria convert copper compounds into soluble copper compounds, separating the copper from the ore in the process.

the leachate contains copper ions which can be extracted by electrolysis or displacement reactions.
scrap iron is often used for displacement

35
Q

how does phytomining work

A

growing plants in soil that contain copper
copper builds up in leaves
harvested, dried and burned in furnace
copper extracted from ash thro displacement/ electrolysis

36
Q

pros of bio-leaching and phytomining

A 
cheap
smaller environmental impact
require less energy 
low grade ores are not mined in same way so beneficial to habitats
however they are slow
37
Q

why is recycling important

A

less energy needed
so saves money
preserves finite resources
less landfill

38
Q

how is glass recycled

A

separated by colour and chemical composition

crushed and melted to reshape

39
Q

what do life cycle assessments do

A

asses the environmental impact of the entire lifetime of a product

40
Q

what are the 4 stages of the lifetime of a product

A

getting raw material
manufacturing and packaging
using product
product disposal

41
Q

at each stage of the LCA, what is considered

A 
energy
water and other resources
pollution 
waste
how the waste is disposed
42
Q

pro and con of incineration

A

less waste goes to landfill
can generate electricity
air pollution

43
Q

selective LCA

A

show only some of the impacts
can be biased
can be written to support claims of a companies

44
Q

what is potable water

A

been treated or naturally safe for humans. can contain lots of other dissolved substances. pH between 6.5 and 8.5, salts are not too high and no dangerous bacteria

45
Q

what is fresh water

A

not much dissolved in it. e.g. rainwater from lakes and reservoirs and groundwater

46
Q

what treatment does fresh water go through

A

filtration - wire mesh, gravel and sand beds filter out solids

sterilization - bubbling chlorine gas through, using ozone or ultraviolet light

47
Q

what is desalination

A

making sea water potable

done via reverse osmosis or distillation which is really expensive

48
Q

how does reverse osmosis work

A

water passed through a membrane that traps ions and larger molecules

49
Q

why is sewage treated

A

to remove organic matter nad harful microbes. instural waste water has to undergo additional stages of treatment

50
Q

what is screening

A

removing large materials like plastic bags and grit sewage is treated

51
Q

what is sedimentation in waste water treatment

A

after screening, swage stands in settlement tank where heavier solids sink to produce a sludge. (sedimentation)

52
Q

what is aerobic digestion in waste water treatment

A

after sedimentation the effluent is treated by biological aerobic digestion where air is pumped through the water to encourage aerobic bacteria to break down any organic matter and microbes

53
Q

what in anaerobic digestion in waste water treatment

A

slug removed from settlement tank and transferred to large tanks where its broken down by bacteria in anaerobic digestion. this releases methane which can be used as an energy source and remaining waste is used as a fertilizer

54
Q

why would you get potable water from waste water

A

in areas where there isnt much water. it requires more processes but uses less energy than desalination of salt water. ppl dont like the idea of drinking water that used to be sewage

55
Q

where does the nitrogen and hydrogen come from thats used in the haber process

A

nitrogen form air

hydrogen from reacting natral gas ( methane) with steam

or from crude oil

56
Q

what is the symbol equation for the haber process

A

N”2 + 3H”2 2NH”3

57
Q

what temp and preasure is used for the haber process

A

450

200atm

58
Q

how is the ammonia gas extracted

A

cooled in a condenser and liquefied and then removed from reaction vessal

59
Q

what catalyst is used in the haber process

A

iron

60
Q

why should the temp be at 450 for haber

A

forward reaction is exothermic so increasing the temp will make the equilibrium shift the wrong way so yield is greater at lower temp.

lower temp = lower ror so 450 is a compromise

61
Q

why is pressure 200atm in haber process

A

high pressure favours forward reaction so high pressure increases the yield

hp also increases ror

however hp means expensive plant

62
Q

why is an iron catalyst used

A

make reaction go faster so reaches equilibrium faster. doesn’t change amount of products at equilibrium. high temp would be needed without them

63
Q

what are the three main essential elements needed by plants

A

nitrogen, phosphorus and potassium

64
Q

why do farmers use fertilizers

A

to replace missing elements or provide more of them because it helps crop yield as the crops can grow bigger and faster

65
Q

what are NPK fertilizers

A

formulations containing salts of nitrogen, phosphorous and potassium in the right percentages

66
Q

what other nitrogen containing compounds can be produced from ammonia

A

+ oxygen then water = nitric acid
+ acids = ammonium acids
+ nitric acid (HNO”3) = ammonium nitrate (NH”4NO”3)

67
Q

why is ammonium nitrate a good component of fertiliser

A

high proportion of nitrogen per unit mass

68
Q

how is ammonium nitrate made in industry

A

ammonia gas is added directly to giant vats containing highly concentrated nitric acid which results in very exothermic reaction. The heat released is used to evaporate water to make a very concentrated ammonium nitrate product

69
Q

how is ammonium nitrate made in the lab

A

titration and crystallisation. much slower and lower concentration so less heat

70
Q

phosphate rock cannot be used as a fertilizer. what can it be made into that can be used

A

+nitric acid = phosphoric acid and calcium nitrate

+ sulfuric acid = calcium sulphate and calcium phosphate

Chemistry (15 decks)

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