Topic 10 (P2) Flashcards
(38 cards)
Properties of ceramics
.Insulators of heat and electricity
.Brittle
Properties of polymers
.Insulators of heat and electricity
.Can be flexible and easily moulded
Properties of metals
.Conductor of heat and electricity
.Ductile
.Malleable
Clay.
Soft material when dug up so can be moulded into different shapes. When fired at high temperatures, it hardens to form clay ceramic.
Used for pottery and bricks.
Soda-lime glass.
Heat mixture of limestone, sand and sodium carbonate until it melts. When the mixture cools, it comes out as glass.
Explain 4 composites
Fibreglass: fibres of glass embedded in a matrix of polymer (plastic).
It has low density (like plastic) but very strong (like glass).
-used for boats, surfboards
Carbon fibre: also have a polymer matrix. The reinforcement is either made from carbon fibres or carbon nanotubes.
Very strong and light
-used in aerospace
Concrete: made from aggregate (sand and gravel) embedded in cement.
Very strong
-used as a building material
Wood: natural composite made of cellulose fibres held together by a polymer matrix
Explain how the properties of polyethene may differ.
.Low density polyethene is made from ethene at a moderate temperature under a higher pressure
-it’s flexible and used for bags and bottles
.High density polyethene is made from ethene but at a lower temperature and pressure with a catalyst
-more rigid and used for water tanks
finish this card
Explain 4 alloys.
Bronze: Copper + Tin
.Bronze is harder than copper
.For medals and statues
Brass: Copper + Zinc
.Brass is more malleable than bronze
.In water taps and door fittings
Gold alloys used for jewellery.
.Pure gold is soft so metals such as zinc, copper and silver added to harden
.Pure gold is 24 carat so 18 carat is 75 % gold
Aluminium alloys used for aircrafts.
.Aluminium has a low density which is important for aircraft manufacture
.But too soft so alloyed with other metals to make it stronger
What is rusting?
Corrosion of iron
What is the word equation for rusting?
Oxygen + iron + water -> hydrated iron (III) oxide
Explain aluminium’s corrosion.
When exposed to air, aluminium oxide forms which creates a protective layer that stops any further corrosion.
Explain the experiment to prove that both air and water are needed for iron to rust.
1) If you put an iron nail in a boiling tube with just water it won’t rust. Oil used to stop air getting in.
2) If you put an iron nail in a boiling tube with just air, it won’t rust (calcium chloride can be used to absorb any water from the air).
3) If you put an iron nail in a boiling tube with water and air, it will rust.
Explain the ways to prevent rusting.
.Painting/coating with plastic- ideal for big and small structures. Can be decorative
.Electroplating- uses electrolysis to reduce metal ions onto an iron electrode . It can be used to coat the iron with a layer of a different metal that won’t be corroded away
.Oiling/greasing- used when moving parts are involved
.Galvanising- placing a more reactive metal such as zinc or magnesium which water and oxygen will react with instead of the iron
What are natural resources?
Sources formed without human input
Give an example of natural products that can be replaced by synthetic products.
Rubber can be extracted from the sap of a tree but man-made polymers have been made to replace rubber e.g. for tired.
Give an example of natural products that can be improved on by synthetic products.
Fertilisers used to increase yield of crops
Define non-renewable.
Reform at a similar rate or faster rate than we use.
Give an advantage and disadvantage of mining metal ores
.Provides local jobs
.Brings money into the area
.Bad for environment as it uses of energy
.Destroys habitats
.Produces lots of waste
What is sustainable development?
Takes account of the needs of present society while not damaging the lives of future generations.
Why might bioleaching and phytomining be used?
To improve sustainability of extracting copper by extracting it from low-grade ores.
Bioleaching.
Bacteria are used to convert copper compounds in the ore into soluble copper compounds, separating out the copper from the ore in the process. The leachate (solution produced) contains copper ions which can be extracted by electrolysis or displacement.
Phytomining.
Plants can be grown in soil that contains copper. The plants can’t use or get rid of the copper so it builds up in the leaves. They plants are harvested, dried and are burned in furnace. The ash contains soluble copper compounds. Copper can be extracted by electrolysis or displacement using scrap iron.
What are the benefits of recycling metals.
Recycling metals often takes less energy than mining and extracting metals.
Cuts down on the amount of waste getting sent to landfill.
Conserves the finite amount of the metal in the earth.
How do they recycle metals?
Melting them (e.g. in a blast furnace) then casting them into the shape of the new product.
