26/06/22 26/06/22 C2 Material Choices C2 Material Choices OCR 21 st Century W Richards
Mar 26, 2015
10/04/2310/04/23
C2 Material ChoicesC2 Material Choices
OCR 21st Century
W Richards
10/04/23C2.1 Properties of Materials
Q. For each of the following materials describe what properties the material needs to have and why…
10/04/23Properties of materials
Plastic (polythene)
• Light
• Flexible
• Easily moulded
10/04/23Properties of materials
Plastic (polystyrene)
• Light
• Rigid
• Good insulation
10/04/23Properties of materials
Nylon
• Light
• Tough
• Waterproof
10/04/23Properties of materials
Polyester
• Light
• Tough
• Waterproof
10/04/23Properties of materials
Unvulcanised rubbers
• Low tensile strength
• Soft
• Flexible
10/04/23Properties of materials
Vulcanised rubbers
• High tensile strength
• Hard
• Flexible
10/04/23C2.2 Crude Oil
10/04/23Using Different Materials
We use a variety of materials from a variety of different places:
Cotton from plants
Silk from silkworms
Wood and paper from trees
These are all “natural” materials – we can also use synthetic (man-made) ones like plastics – these are often made from materials from within the Earth like crude oil.
10/04/23Chemical formulae
The chemical formulae of a molecule or compound is simply a way of showing the ratio of atoms in it. For example…
Na
Cl = sodium chloride (NaCl)
K I = potassium iodide (KI)
K N
O
O
O
= potassium nitrate (KNO3)
10/04/23Chemical formulae
Try drawing these:
1) Water H2O
2) Carbon dioxide CO2
3) Calcium sulphate CaSO4
4) Magnesium hydroxide Mg(OH)2
10/04/23Simple chemical reactions
Mg OH Cl
Mg ClCl
HH OH Cl
Magnesium
+ Copper sulphate
Mg
O
OCu
O
O S Cu Mg
O
O
O
O S
Magnesium
sulphate
Copper +
H2OMgO +
WaterMagnesium oxide
+ Hydrochloric acid
Magnesium chloride
+
2HCl MgCl2 +
MgSO4Mg + CuSO4 Cu +
Notice that the number of atoms on each side of the equation is the same!
10/04/23Hydrocarbons and crude oil
Incre
asin
g le
ng
th
Crude oil is a mixture of HYDROCARBONS (compounds made up of carbon and hydrogen). Some examples:
Ethane
C C
HH
H
HH
H
Butane
C C
HH H
HH
H C C H
H
HH
These different “lengths” are called “_______” and most of them are used as _____. Some are used to make materials such as _______. Longer chains have higher _____ points.
Words – boiling, fractions, plastics, fuels
10/04/23Fractional distillation
Crude oil can be separated by fractional distillation. The oil is evaporated and the hydrocarbon chains of different lengths condense at different temperatures:
Fractions with low boiling
points condense at
the top
Fractions with high boiling
points condense at the bottom
10/04/23Forces between molecules
Weak force of interaction here
Longer molecules = stronger force of attraction, leading to higher boiling points due to the molecules needing more energy to “pull” them away from each other.
10/04/23Polymers
C CHH
HH
Ethene
Here’s ethene. Ethene is called a MONOMER because it is just one small molecule. We can use ethene to make plastics…
Step 1: Break the double bond
Step 2: Add the molecules together:
This molecule is called POLYETHENE (i.e. polythene), and the process that made it is called POLYMERISATION
10/04/23C2.3 Molecular Structure
10/04/23Uses of addition polymers
Poly(ethene) Poly(propene)
Poly(chloroethene), PVC
Poly(styrene)
10/04/23Structure of Plastics
1) Some plastics have ____ intermolecular forces between each molecule – these have __ melting points and can be ________ easily
2) Some plastics have _____ forces between each molecule. These have ____ melting points and are ____.
Words – high, low, strong, weak, stretched, rigid
10/04/23Forces between molecules
As we’ve already said, longer molecules have stronger forces of attraction between them. This tends to lead to longer chain plastics being:
1) Stronger
2) Stiffer
3) Harder
4) More difficult to melt (i.e. higher melting point)
10/04/23Modifying Plastics
Polymers can be modified in a number of ways:
1) Increasing the chain length
...making it stronger
2) Crosslinking
...making it harder
3) Plasticizing
...making it softer and more flexible
4) Packing more closely (a crystalline polymer)
...making it stronger and more dense
10/04/23C2.4 Nanotechnology
10/04/23Nanotechnology
Task: To find out what nanotechnology is and what it is used for
1) What is nanotechnology?
2) Define the terms nanoparticle and nanocomposite
3) Gives some examples of its uses
4) Describe some of the future uses of this technology
5) Describe some of the ethical concerns over this technology
10/04/23Nanotechnology
Nanotechnology is a new branch of science that refers to structures built from a few hundred atoms and are 1-100nm big. They show different properties to the same materials in bulk, partly because they also have a large surface area to volume ratio and their properties could lead to new developments in computers, building materials etc.
Definition:
10/04/23How nanoparticles are formed
Nanoparticles can be formed by a number of methods:
They can occur naturally in sea spray
They can also be formed during combustion
Or they can be formed by grinding down materials
10/04/23Two examples of nanotechnology
The “Nano Carbon Pro” tennis racket uses nanoparticles to increase its strength.
Silver nanoparticles can be used to give fibres antibacterial properties – look at what they do to e-coli bacteria:
Normal e-coli
E-coli affected by silver
nanoparticles
10/04/23Nanoscience and health
Nanoparticles are obviously very small and, as we have said, have a large surface area to volume ratio. This makes them useful but can also make them dangerous. Nanoparticles could easily pass through a cell membrane:
How do these health concerns affect the development of nanotechnology?
I’m going to die…