Flashcards in Using resources Deck (45)
What are ceramics?
Non-metals with high melting points not made from carbon based compounds
What are two common examples of ceramics?
What are composites?
A material made up of two or more materials embedded in each other.
What do the properties of composites depend on?
what the composite is made from
What are some examples of composites? And what are their properties?
fibreglass (glass fibres embedded in polymers) - has a low density (from the polymers) but is strong (from the glass)
Carbon fibre (long chains of carbon joined together) - strong and light
Concrete (aggregate [any material made from fragments, eg. sand and gravel] embedded in cement) -very strong
Wood (natural composite)
What influences the properties of a polymer?
how it's made
what it's made from
What do the monomers a polymer is made from determine?
the type of bonds that form between the polymer chains
the weak bonds between the chains affect the properties of the polymer
What are alloys and why do we use them?
Alloys are a metal with another element added to it to change the properties to make the metal more appropriate for its use. We use them instead of metals as they are better for its job, for example an alloy could be harder and stronger than the original metal.
What are steels?
alloys of iron
What properties does low carbon steel have? What can it be used for?
What properties does high carbon steel have? What can it be used for?
very hard and inflexible
blades for cutting tools or bridges
What properties does stainless steel have? What can it be used for?
cutlery or containers for corrosive substances
What is bronze an alloy of?
copper and tin
What is brass an alloy of?
copper and zinc
What are gold alloys used for?
What are aluminium alloys used for?
What is rust?
hydrated iron (III) oxide
corrosion of iron
What is corrosion?
Where metals react with substances in their environment and are gradually destroyed
How does stainless steel prevent rust?
Stainless steel contains aluminium. When aluminium is exposed to air, it reacts to form aluminium oxide, which acts as a protective layer as none of the rest of the metal is exposed to air or water, meaning it can not rust.
What experiment can you do to show that air and water are needed for rusting?
set up three test tubes:
in one, have an iron nail in water (with no air; boil the water and put a layer of oil on top to keep out air) to show that the iron won't rust without air
in another, have air with no water (use calcium chloride to absorb any water) to show that water is needed to rust
in the third, have some water and air to show that the iron nail rusts with water and air
How can you prevent rusting?
Coating the iron (eg. painting, coating with plastic, electroplating, oiling, greasing)
Sacrificial protection (placing a more reactive metal with the iron so that that metal reacts with the air instead of the iron)
What are natural resources?
Resources that form without human input, eg cotton and fossil fuels
What are renewable resources?
Resources that reform at a similar (or faster) rate than they are used, so do not run out.
What are finite resources?
Non-renewable resources that will run out because they aren't formed quickly enough to replaceable.
What is sustainable development?
approach to development that takes account of present society whilst not damaging future generations
How can we make finite resources last longer?
Reduce how much we use them (this also reduces how much needs to be produced, which will also reduce the use of anything needed to make them)
How can the sustainability of copper be improved?
bioleaching (bacteria used to separate copper compounds)
phytomining (growing plants in soil that contains copper so that copper builds up in the leaves, which can then be harvested, dried and burned so that copper can be extracted)
Why are metals recycled?
recycling them uses much less energy than is needed to mine and extract new metal
conserves the finite amount if each metal in the earth
reduces the amount of waste that goes to landfill sites
How can glass be recycled?
by being crushed, melted and reshaped to use in glass products
alternatively, glass bottles can be reused without needing to be reshaped.