CHAPTER 15 Flashcards
1
Q
what is corrosion caused by
A
chemical reactions between the metal and chemicals in the environment
2
Q
what is rusting
A
the corrosion of iron
3
Q
what two conditions are needed for iron to rust
A
oxygen and water
4
Q
why des the mass of iron increase as it rusts
A
the atom bond with the oxygen and water molecules which makes a compound that is heavier than iron
5
Q
equation for the rusting of iron III
A
iron + oxygen+ water-> hydrated iron III oxide
6
Q
what happens to the iron when it rusts
A
it is oxidised
7
Q
3 ways of barriers to stop rusting
A
paint
oil
plastic
8
Q
what is the sarcrifical method of preventing rusting
A
a more reactive metal is placed onto the iron so the iron stays intacts
9
Q
what happens when iron is galvanised
A
it is covered with a layer of zinc so the oxygen and water oxidise and react with zinc and not iron
10
Q
why isn’t aluminium completely destroyed by corrosion
A
aluminium oxide forms a protective layer that stops any further reaction taking place
11
Q
why is iron completely destroyed by rusting
A
iron oxide is flaky and will fall off to leave more iron exposed to react again
12
Q
what is an alloy
A
a mixture of a metal and another material
13
Q
why are allows much harder than normal metals
A
the structure of the metal so disrupted so the layers cant slide over eachother
14
Q
what is bronze made from
A
copper + tin
15
Q
why is bronze better than copper
A
it is much harder
16
Q
uses of bronze 3
A
makes medals
decorative
ornaments and statues
17
Q
what is brass made from
A
cooper + zinc
18
Q
why is brass better than bronze
A
it is more malleable and is used where there needs to be little friction
19
Q
uses of brass 3
A
musical
instruments taps
door fittings
20
Q
what is the most useful property of aluminium
A
it is low density
21
Q
why is aluminium alloyed
A
to make it stronger
22
Q
uses of aluminium alloys 2
A
aircraft
plating on military vehicles
23
Q
why is gold alloyed
A
to make it stronger
24
Q
why is copper mixed with gold
A
it is more long wearing
25
uses of gold alloys
jewellery
26
what is 24 carat gold
pure gold
27
how to work out how much gold is in a carat
divide by 24
28
what are steels
alloys of iron with carbon and other elements
29
what are the simplest steels
carbon steels
30
how are carbon steels made
most of the carbon is removed from the iron
31
uses of carbon steels 3
car bodies
ships
structural ships
32
properties of high carbon steels
strong but brittle
33
properties of low carbon steels 2
soft and easily shaped
34
what are nickel steel alloys used for and why
long span bridges , bicycle chains resistant to stretching forces
35
what is stainless steel made from
chromium and nickel
36
characteristics of stainless steel 2
don't rust
| very strong
37
uses of stainless steels
cutlery
| cooking utensils
38
what do the properties of a polymer depend on
the monomers used to make it
| the conditions under which the reaction happened
39
what are the two types of polyethene
low density polyethene
| high density polyethene
40
how is low density polyethene made
very high
| temperaatures and a catalyst
41
what is ld polyethene used for and why
plastic bad and bottles
| it is very flexible
42
what gives ld polyethene its lolw density
the polymer chains are randomly branched and cant pack closely together
43
how is hd polyethene made
lower temperature and a different catalyst
44
uses of LD polyethene and why
water tanks
| it is very rigid
45
what gives HD polyethene its high density
the polyethene chains are straighter and can pack together more closely
46
what are thermosetting polymers
the don't soften when heated because of cross links between polymer chains
47
what are thermosoftening polymers
they soften when heated
| made of individual polymer chains tangled together
48
what allows thermosoftening polymers to soften under heat
weak intermolecular forces between polymer chains that need little energy to overcome
when it cools the forces bring the polymer back together again
49
what stops thermosetting polymers from softening under heat
the monomers from covalent cross links between polymer chains which are strong an wont soften
50
what is glass mainly made from
sand
51
how is glass made
the raw materials are heated - sand limestone and sodium carbonate
they melt and react to form molten glass
when they cool, they remain in this disorganised structure
52
how to make different types of glass
use different raw materials
53
what is different about borosilicate glass and what is it used for
it has boron trioxide in it
| it is used for oven ware as it has a high melting point
54
what are ceramics
non metal solids with high melting points that aren't made from carbon based compounds
55
examples of ceramics made from clay 3
bricks crockery and toilets
56
how are clay ceramics made
wet clay is moulded into desired shape and heated
57
why do the properties of clay change so drastically when heated
there is ionic bonding between metals and non metals in clay covalent bonding
between non metals arranged in giant layers when wet water gets between layers and makes them slimy
when they are heated water is driven out and strong bonds for between layers
58
what are composites made from
one materials embedded in another
59
4 examples of composites
fibreglass
carbon fibre
concrete
wood
60
why is natural wood so srong
cellulose
61
what is a matrix in a composite
it acts as a bonder and holds everything together
62
what is fibreglass made from
fibre of glass embedded in a matrix made of plastic
63
properties of fibreglass 2
low density
| very strong
64
what is fibreglass used for 3
skis
boats
surfboards
65
what is concrete made from
aggregate embedded in cement
66
use of concrete
buiding materials
67
what is carbon fibre made form
long chains of carbon atoms in plastic
| carbon nanotubes in plastic
68
use of carbon fibres
aerospace
sports car
manufacturing
69
what do most fertilisers contain
nitrogen
| phosphorous and potassium
70
why do fertilisers contain nitrogen and similar nutrients
crops grow and absorbs nutrients for growth
farmers harvets plants so little of the plant is allowed to decompose and add nutrient back into the soil
so farmers hve to replace the missing nutrients or provide more of them
71
even though there is a lot of nitrogen in the air why don't plants absorb it
the gas is insoluble in water and plants can only absorb a soluble form of nitrogen
72
even though there is a lot of nitrogen in the air, why don't plants absorb it
the gas is insoluble in water and plants can only absorb a soluble form of ntirogen
73
what is the haber process
nitrogen and hydrogen are converted to ammonia which is used in fertilisers
74
who created the haber process
german scientist
| fritz haber
75
what I the most important us of ammonia
fertilisers
76
how is the nitrogen for the haber process sources
obtained from the air
77
how is hydrogen sourced for the haber process
methane is reacted with steam to form hydrogen and carbon dioxide
78
what are the three conditions used in the haber process
iron catalyst
high temperature
high pressure
79
the haber process
nitrogen and methane are sourced they are passed over an iron catalyst at high temperature and pressure
this reaction is reversible so some ammonia formed is converted back to the raw materials a dymanic equilibrium is reached. ammonia formed as a gas it is collected condensed and turned into fertiliser. the unused reactants are recycled so nothing is wasted
80
how is ammonia obtained from the haber process
te gases are cooled ammonia liquefies and can be separated
81
equation for haber process
nitrogen + hyfrogen ammonia + heat
82
equation for the formation of hydrogen
methane + steam-> hydrogen + carbon dioxide
83
why are fertilisers used
replace missing nutrients increases crop yield
| crops grow faster and bigger
84
how to create ammonia nitrate
ammonia + nitric acid
85
how is ammonia phosphate formed
ammonia + phosphoric acid
86
when are salts formed
when acids and alkalis react together in a neutralisation reaction
87
is ammonia solution alkali or acid
alkali
88
how is ammonium nitrate formed in industry
in gaint vats high concentrations very exothermic reaction
| then heat released evaporates water, leaving a very concentrated ammonium nitrate product
89
how is ammonim nitrate formed in the lab
smaller scale titration and crystallisation reactants are at a lower concentration less heat produced after titration, the solution is crystallised to result in pure ammonium nitrate crystals
90
why is crystallisation not used in industry
it is too slow
91
ho to make ammonium sulfate
react ammonia with sulfuric acid
92
what is npk fertiliser
nitogren , phosphorous and potassium fertiliser
93
where to source phosphorous
rocks
94
why is acid added to phosphorous rocks
plants cant use it as it is insoluble in water
95
what is produced when phosphate rock is reacted with nitric acid
phosphoric acid and calcium nitratr
96
what is produced when phosphate rock is react with sulfuric acid
calcium suflate and calcium phosophate also known as single superphosphate
97
what is produced when phosphate rock is reacted with phosphoric acid
tripe superphosphate
98
how is nitrogen obtained from air
air Is cooled to -200 c to liquefy it fractional distillation happens
99
reaction for methane+ steam
methane + steam-> hydrogen + carbon monoxide
100
what is the main cost of producing ammonia
sourcing the methane, which is a natural gas
101
why is 200 atmospheres of pressure used
there are less moles of ammonia then reactants so higher pressure - higher yield
but higher pressure is also expensive and dangerous so 200 atmospheres is a compromise
102
why is an iron catalyst used
it speeds up both the forward and reverse reaction doesnt affect yield of ammonia but makes it be produced quicker
103
what is the forward reaction of the production of ammonia
exothermic
104
why is 450 c used for the haber process
forward reaction is exothermic increasing temperature = less yield
bbut decreasing temperature = slower rate of reaction and minimises effect of catalyst
450 c is a compromise between maxiumum yield and speed of reaction
