C2 - Material Choices Flashcards
Give one example of a chemical element
Iron
Name a material we use that comes from plants
Wood and paper are both made from trees
Cotton comes from the cotton plant
Name a material we use that comes from animal
Wool comes from sheep
Silk is made by the silkworm larva
Leather comes from cows
Why do we use both natural and synthetic rubber?
Naturally it comes from the sap of the rubber tree so is cheaper to use from the sap of the tree
Synthetically rubber is made in a factory which means that you can control its properties, making it suitable for different purposes e.g. wetsuits
Whats the difference between compressive and tensile strength?
Compressive strength is how much a material can resist a pushing force
Tensile (or tension) strength is how much a material can resist a pulling force
What’s the hardest material found in nature?
Diamond
Give a definition of density
Density is a material’s mass per unit volume (e.g. g/cm3)
You’re measuring the properties of a material. Give three reasons why your results might not be accurate
- There might be a fault in your equipment
- Wrong results can because of human - inaccurate measuring, reading or recording of the results
- Your samples and techniques have to be the same every time
Why should you always repeat your measurements?
It will allow for faults in the equipment, human error etc. It will then make your results more accurate.
How can you ensure that an experiment is a fair test?
Vary only one factor in your experiment and to only measure one thing at a time. Each time you repeat the test the other factors must be exactly the same.
Name two properties of plastic that make them useful in manufacturing
Can be fairly hard, strong and stiff
Some are fairly low density (good for lightweight goods)
Some are mouldable (easily made into things)
Name two properties of rubber that make them useful in manufacturing
Strong but soft and flexible
Mouldable
Name two properties of nylon that make them useful in manufacturing
Soft and flexible
Good tensile strength
Name three properties that you’d look for when choosing a material to make a child’s dinner bowl
Non-toxic Stiff Non-brittle Hard Fairly high melting point
What does crude oil contain?
A mixture of hydrocarbons, these chains are of varying lengths
Briefly describe what happens during polymerisation
Under high pressure many small molecules ‘join hands’ (polymerise) to form long chains called polymers
Give an example of a product where a polymer has replaced a natural material
Window frames used to be made from wood. Many new window frames are made from uPVC, a synthetic polymer.
How does the arrangement of polymer chains affect the density of a material?
If the polymer chains are packed close together, the material will have a high density.
If the polymer chains are spread out, the material will have a low density.
A polymer is easily stretched and has a low melting point. What can you say about the arrangement of its molecule chains and the forces holding them together?
Chains held together by weak forces are free to slide over each other
What would you add to a polymer to make it stiffer and stronger?
Crosslinks hold the chains firmly together and will result in stronger forces so will make it stiffer and stronger. (Crosslinks are chemical bonds between the polymer chain)
How do plasticisers work?
They can be added to a polymer to make it softer and easier to shape. Plasticisers work by getting in between the polymer chains and reducing the forces between them
What are the properties of a crystalline polymer?
Crystalline polymers has straight chains with no branches so the chains can fit close together. Crystalline polymers have higher density, are stronger and have a higher melting point.
Name the four main stages considered in a life cycle assessment
Extracting and refining raw materials
Manufacturing the product
Using the product
Disposing of the product
Explain why a Life Cycle Assessment can’t tell you whether you should make a product or not
You have to consider other things when you’re making your decision:
- Making the product will benefit some people (like employers) and some products are essential to their customers (syringes for diabetics)
- Some people may be badly affected (e.g. land pollution)
- Many countries have laws which limit how much impact a company can have on the environment
Give an example of a sustainable development
A paper company only using wood from forests that are replanted and regrow faster than the company is felling them, and taking steps to protect the wildlife that lives in the forests
Why do we use both natural and synthetic rubber?
Cheaper to use naturally from the sap of the rubber tree
Synthetically rubber is made in a factory which means that you can control its properties, making it suitable for different purposes e.g. wetsuits
What does crude oil contain?
Mixture of hydrocarbons, chains are of varying lengths
What would you add to a polymer to make it stiffer and stronger?
Crosslinks. Holds the chains firmly together and will result in stronger forces so will make it stiffer and stronger. (Crosslinks are chemical bonds between the polymer chain)
