C10: MATERIALS

Question 1

What is an alloy?

Answer 1

a mixture of a metal with small amounts of other elements

Question 2

Steels:
-main metal
-other elements
-uses

Answer 2

-main metal: iron
-other elements: carbon (stainless steel - chromium and nickel)
-uses: cutlery, construction, cars

Question 3

Gold alloys:
-main metal
-other elements
-uses

Answer 3

-main metal: gold
-other elements: silver/copper/zinc
-uses: jewellery

Question 4

How many carats pure gold?

Answer 4

24 carat

Question 5

How do you calculate the % of gold in an alloy?

Answer 5

(no. of carats/24) x 100

Question 6

Brass:
-main metal
-other elements
-uses

Answer 6

-main metal: copper
-other elements: zinc
-uses: brass instruments, brass pins in plugs

Question 7

Bronze:
-main metal
-other elements
-uses

Answer 7

-main metal: copper
-other elements: tin
-uses: statues, coins

Question 8

What is corrosion?

Answer 8

the destruction of materials (esp metals) by chemical reactions with water/O2

Question 9

What is rusting?

Answer 9

corrosion when iron or steel reacts with oxygen and water

Question 10

What is the word equation for rusting?

Answer 10

iron + oxygen –> iron oxide

Question 11

What needs to be present for rusting to occur?

Answer 11

water

Question 12

What are the 2 methods of preventing corrosion?

Answer 12

-protective layer
-sacrificial protection

Question 13

Protective layer:
-how it works
-examples

Answer 13

-acts as a barrier which stops it reacting with O2 and water
-examples: paint, oil, plastic, any less reactive metal

Question 14

Sacrificial protection:
-how it works
-examples

Answer 14

-zinc often used to coat iron nails because it is more reactive so any water and O2 that comes into contact with the nail reacts with the zinc and not with the iron
-examples: any more reactive metal

Question 15

Clay

Answer 15

-soft when dug up out of the ground so it can be moulded into different shapes
-when fired at high temps it hardens to form a clay ceramic
-ideal for making pottery and bricks

Question 16

Glass (properties)

Answer 16

-transparent
-can be moulded when hot
-brittle when thin

Question 17

What are the 2 types of glass

Answer 17

-soda-lime glass
-borosilicate glass

Question 18

How is soda-lime glass made?

Answer 18

-made by heating a mixture of limestone, sand and sodium carbonate
-when mixture cools it comes out as glass

Question 19

How is borosilicate glass made?

Answer 19

-made by heating a mixture of sand and boron trioxide
-when mixture cools it comes out as glass

Question 20

What are composites?

Answer 20

a material made from two or more different materials with contrasting properties

Question 21

What are the components of composite materials?

Answer 21

-the reinforcement (fibres/fragments of a material)
-the matrix (acts as a binder and holds reinforcement together)

Question 22

What are some examples of composites?

Answer 22

-fibreglass
-carbon fibre
-concrete
-wood

Question 23

Fibreglass:
-reinforcement
-matrix
-properties
-uses

Answer 23

-reinforcement: glass fibres
-matrix: polymer
-properties: low density, very strong
-uses: skis, boats, surfboards

Question 24

Carbon fibres:
-reinforcement
-matrix
-properties
-uses

Answer 24

-reinforcement: carbon fibres/nanotubes
-matrix: polymer
-properties: strong, light
-uses: aerospace, sports car manufacturing

Question 25

Concrete:
-reinforcement
-matrix
-properties
-uses

Answer 25

-reinforcement: aggregate (mixture of sand and gravel)
-matrix: cement
-properties: very strong
-uses: building (eg: pavements/in skate parks)

Question 26

Wood:
-reinforcement
-matrix

Answer 26

natural composite
-reinforcement: cellulose fibres
-matrix: organic polymer

Question 27

What are the 2 factors that influence the properties of a polymer?

Answer 27

-how it is made
-what it is made from

Question 28

What do the properties of poly(ethene) depend on?

Answer 28

-reaction conditions
-use of a catalyst

Question 29

How is low density (LD) poly(ethene) made?

Answer 29

-made from ethene
-moderate temp
-high pressure

Question 30

What are the properties and uses of LD poly(ethene)?

Answer 30

-low density
-flexible
-used for bags and bottles

Question 31

How is high density (HD) poly(ethene) made?

Answer 31

-made from ethene
-lower temp
-lower pressure
-catalyst present

Question 32

What are the properties and uses of HD poly(ethene)?

Answer 32

-high density
-more rigid
-used for water tanks and drainpipes

Question 33

The _________ that a polymer is made from determine the type of ______ that form between the polymer chains. these _____ _____ between the different molecule chains determine the _______ of the polymer

Answer 33

the monomers that a polymer is made from determine the type of bonds that form between the polymer chains. these weak bonds between the different molecule chains determine the properties of the polymer

Question 34

What are the 2 different types of polymers?

Answer 34

-thermosoftening polymers
-thermosetting polymers

Question 35

Thermosoftening polymers

Answer 35

-melt when heated
-weak intermolecular bonds between polymer chains
-can be remoulded

Question 36

Thermosetting polymers

Answer 36

-do not melt when heated
-strong covalent bonds form cross links between polymer chains
-when heated, cross links do not allow the chains to separate
-cannot be remoulded