C15 Using Our Resources

Question 1

What is rust?

Answer 1

The corrosion of iron

Question 2

what are the conditions needed for rusting?

Answer 2

air and water

Question 3

what is the chemical name of rust?

Answer 3

hydrated iron oxide

Question 4

how can rust be prevented?

Answer 4

• paint
• oil/grease
• plastic coating
• less reactive metal
• more reactive metal

Question 5

what is sacrifical protection?

Answer 5

a method of preventing rusting where a more reactive metal than iron is attached or coated on an object

Question 6

what does galvanised mean?

Answer 6

iron or steal objects that are protected from rusting by a thin layer of zinc metal on their surface

Question 7

when is sacrificial protection used?

Answer 7

when the conditions are harsh such as in seawater

Question 8

what accelerates rusting?

Answer 8

seawater

Question 9

what is an alloy?

Answer 9

a mixture of two or more elements where at least one is a metal

Question 10

why are alloys used?

Answer 10

it makes the metal harder
this is because differently sized particles make it harder for layers to slip over each other

Question 11

what are some alloys of copper and what are they made from?

Answer 11

• bronze (copper ant tin)
• brass (copper and zinc)

Question 12

why is gold alloyed and what is it alloyed with?

Answer 12

it is alloyed to make it harder
it is usually alloyed with copper

Question 13

what are steels?

Answer 13

alloys of iron with carbon and other elements

Question 14

why is pure iron not used?

Answer 14

it is too soft to be usefull

Question 15

how can you change the properties of steel?

Answer 15

carefully controlling quantities of carbon and other elements added to the iron

Question 16

how are carbon steels made?

Answer 16

removing most of the carbon from the iron in the blast furnace

Question 17

what are the properties of high carbon steels?

Answer 17

very hard but brittle

Question 18

what are the properties of low carbon steels?

Answer 18

softer and more easily shaped

Question 19

what are the substances in stainless steel?

Answer 19

chromium
nickel
iron

Question 20

what are the properties of stainless steels?

Answer 20

resistant to corrosion

Question 21

how can the properties of a polymer be altered?

Answer 21

• different monomers
• the conditions of the reaction

Question 22

what are the conditions to produce low density poly(ethene)?

Answer 22

high pressures
a trace of oxygen

Question 23

what is the structure of LD poly(ethene)?

Answer 23

the polymer chains are randomly branched and cannot pack closely together

Question 24

what are the conditions to produce high density poly(ethene)?

Answer 24

catalyst
50 degrees C
slightly raised pressure

Question 25

what is the structure of HD poly(ethene)?

Answer 25

straighter chains that can pack more closely

Question 26

what are thermosoftening polymers?

Answer 26

polymers which will soften or melt easily when heated due to their weak intermoleculular forces

Question 27

what are thermosetting polymers?

Answer 27

polymers that do not melt when heated

Question 28

why do thermosetting polymers not melt?

Answer 28

they have 'cross-links' (covalent bonds between chains) which stop them from softening

Question 29

what is soda glass made of?

Answer 29

heating sand, limestone and sodium carbonate

Question 30

what is borosiliate glass made from?

Answer 30

sand and boron trioxide

Question 31

what are the properties of borosiliate glass?

Answer 31

it melts at a higher temperature than soda-lime glass

Question 32

what are ceramics?

Answer 32

objects made from clay such as pottery and bricks

Question 33

what compounds does clay contain?

Answer 33

metal compounds non-metals with ionic bonding and covalent bonding

Question 34

how are clay ceramics made?

Answer 34

shaping wet clay and then heating in a furnace

Question 35

why are ceramics brittle?

Answer 35

a sharp blow can distort the layers in the structure so that ions with like charges are adjacent and repel each other which cracks the object

Question 36

what are the two materials in composite materials?

Answer 36

- matrix (one acting as a binder) - other material which give structure or strength

Question 37

why are composite materials used?

Answer 37

theu improve a desirable property than neither of the original materials could offer alone

Question 38

why do plants need nitrogen?

Answer 38

they need it to grow as it is needed to make proteins

Question 39

why can plants not obtain nitrogen from the air?

Answer 39

the gas is insoluble in water and most plants can only absorb a soluble form of nitrogen

Question 40

what are the raw materials to make ammonia in the Haber process?

Answer 40

- nitrogen from the air - hydrogen from natural gas

Question 41

what are the conditions of the Haber process?

Answer 41

- 450 degrees C - 200 atmospheres of pressure - iron catalyst

Question 42

what happens to unreacted nitrogen and hydrogen in the haber process?

Answer 42

it is recycled back into the reaction vessel

Question 43

how is ammonia separated from unreacted hydrogen and nitrogen?

Answer 43

cooling the gases so that the ammonia liquifies

Question 44

why is a pressure of 200 atmospheres used in the Haber process?

Answer 44

to increase the yield of ammonia if higher pressures are used, the plant would be too expensive to run and build

Question 45

why is a temperature of 450 degrees C used for the Haber process?

Answer 45

lower temperatures would increase the yield but it would produce too slowly?

Question 46

what is the effect of a catalyst in the Haber process?

Answer 46

it speeds up the rate of the forward and backward reaction so causes ammonia to be produced more quickly

Question 47

what is produced when ammonia is neutralised with sulfuric acid?

Answer 47

ammonium sulfate fertiliser

Question 48

what is used to make ammonium phosphate fertiliser?

Answer 48

ammonium sulfate fertiliser and phosphoric acid or phosphate rock is reacted with nitric acid to produce phosphoric acid this is then neutralised with ammonia

Question 49

what are NPK fertilisers?

Answer 49

mixtures of compounds which supply nitrogen, phosphorus and potassium

Question 50

what are the sources of phosphorus?

Answer 50

deposits of phosphate containing rock which is dug or mined

Question 51

where does potassium come from for NPK fertilisers?

Answer 51

potassium salts potassium chloride or potassium nitrate mined from the ground

Question 52

what is the main compound of nitrogen in NPK fertilisers?

Answer 52

ammonium nitrate

Question 53

how is ammonium nitrate made?

Answer 53

ammonia is used to make nitric acid nitric acid is reacted with more ammonia

Question 54

what is single superphosphate?

Answer 54

when phosphate rock is treated with sulfuric acid which mades a mixture of **calcium sulfate** and **calcium phosphate**

Question 55

how can you make triple superphosphate?

Answer 55

if phosphate rock is treated with phosphoric acid