C2 - Material Choices Flashcards
Tensile strength
The force needed to break a material which stretched
Compressive strength
The force needed to crush a material which it is being squeezed
Stiffness
The force needed to bend a material
Hardness
How well a material stands to wear, it can be compared by scratching two materials together
Density
The mass of a given volume of the material
What unit is density measured in?
Mass per volume: g/cm3 or kg/m3
What is the word equation for calculating density?
Mass
——— = Density
Volume
What is rubber used for and why?
Rubber is used for car tyres because it is hard and elastic
What are fibres used for
To weave cloth into clothes
What is the main property of plastics?
They keep their shape when moulded: not malleable
Name three plastics which float in water
HDPE (High Density polythene), LDPE (Low Density polythene) and PP (Poly propene)
Name three plastics which soften in boiling water
LDPE, Polystyrene and PMMA
What is the density of HDPE?
0.97g/ cm3
What is the density of LDPE?
0.94g/ cm3
What is the density of PP?
0.91g/ cm3
Outlier
A result which is different or incorrect in comparison to the overall pattern
Mean
Average
Range
The smallest to largest result
Give 3 Properties of metals
- Shiny
- Malleable
- Electrical conductors
Give 3 examples of ceramics
Clay, glass and cement
What are the main two properties of ceramics?
They are hard and strong
What is concrete a mixture of?
Sand and cement
What is bronze a mixture of?
Copper and tin
Name 3 natural materials:
Wool, cotton and silk
Name 3 synthetic materials:
Polyester, nylon and polystyrene
Name 3 natural materials which are extracted from the earth’s crust:
Limestone, iron ore and crude oil
Why have synthetic materials replaced some natural ones? 3 reasons
- Some natural materials are in short supply
- They can be designed to give particular properties
- They are often cheaper and can be made in the quantity needed
Crude oil
A mixture of thousands of hydrocarbons.
Hydrocarbons
Compounds made up of just hydrogen and carbon atoms
What is made when fuels burn in oxygen?
Carbon dioxide and water
How much of crude oil is used as fuel?
Nearly 90%
How much of crude oil is used to synthesise other chemicals?
Around 3%
Name two chemicals which are synthesised from crude oil?
Ethanol and plastics
Fractional distillation
The process which is carried out to separate crude oil
What happens during fractional distillation?
- The oil is heated up which turns it into gases
- The distillation tower gets cooler as it gets higher
- Gas molecules condense into liquids when they cool
- Liquids with similar boiling points collect together
Fractions
The areas in a fractional distillation tower where liquids with similar boiling points collect together
The smaller the molecule chain length, the _____ the boiling point and the _______ the intermolecular forces:
The lower the boiling point and the weaker/ smaller the intermolecular forces
Polymer
A large molecule made by joining many smaller molecules called monomers
Polymerisation
The process by which polymers are made
Alkenes
Hydrocarbons that contain a carbon-carbon double bond.
What happens during polymerisation
One part of the alkene double bond breaks in each molecule and they both join to make a polymer
Give 3 advantages of synthetic materials
Cheaper, you can change their properties, easy to clean, lighter and stronger
What is the structure of LDPE
- It has long molecules with branches
* Weak intermolecular forces
What is the structure of HDPE
- It has long chains but no branches
- More Crystalline than LDPE
- Strong intermolecular forces
- High melting point
Plasticisers
Small molecules which are inserted into polymer chains to keep them apart
Thermoplastics
Plastics which soften when heated and can be moulded into shape
Thermosetting plastics
Plastics which do not soften when heated and contain cross-links which lock the molecules together so they cannot melt
Give two methods someone can use to increase the crystallinity of a chemical
- By drawing the polymer through a tiny hole when it is heated
- By removing branches of the main polymer chain
What is the width of a human hair?
0.1mm
Nano particles
Materials which contain up to a thousand atoms
Nanotechnology
The use and control of tiny matter
What units are nano particles measured in?
Nanometres nm
A nanometer is one _______ of a metre
Billionth
Buckyballs
Very strong carbon spheres made of 60 Carbon atoms
Why are nano particles excellent catalysts
They have large surface areas so they have more reaction areas
Uses of silver nano particles and what they do:
- They kill bacteria
- They can be added to fibres and woven into socks, put into wound dressings, put into plastic and made into food containers
Uses of titanium oxide particles and what they do:
•They are used in sunscreen and make it transparent and absorb uv light
Composites
Materials where nano particles have been combined with materials like metals, ceramics and plastics
What are graphene sheets and what are they used for?
One atom thick sheets of graphite which can be rolled into Carbon nanotubes
What are the problems with the use of silver nano particles?
- They can be washed into the sewers and kill the useful bacteria
- They could then get out into the environment and kill all useful microorganisms
Why are nano particles added to plastic sports equipment?
They make it stronger
Why are nano particles added to tennis balls?
To make them stay bouncy for longer
Why are nano particles added to rubber used in tyres?
To make it more hard wearing
Arguments for and against the use of nanoparticles, give an example from each side
FOR: They occur naturally so must be safe
AGAINST: They might be breathed in from the air and cause lung damage, they can be passed through the skin and into the blood and organs, no one knows if nanoparticles used in solids can escape into the air, some want proof that new nanotechnologies won’t create health and environment risks
Risk
The chance of an event occurring and the consequences if it did
Melting point
The temperature at which a solid turns into a liquid
What is the order of gases in the fractional distillation column from top to bottom? (7)
Bottled gas, Petrol, Parrafin/ Aircraft fuel, Diesel, Central heating oil, Ship & power station oil, Bitumen for roads & roofing
TO REMEMBER
BOTTLE; PETROL; AIRCRAFT; DIESEL; HEATING; SHIPS; ROADS
