Using Materials (AQA GCSE Chemistry)
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What is rust?
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What is rust?
Rust is the hydrated iron(III) oxide that forms on iron when it corrodes.
Which element does rusting specifically refer to?
Rusting specifically refer to the corrosion of iron.
Write the word equation for the corrosion of iron.
The word equation for the rusting of iron is:
iron + water + oxygen ⟶ hydrated iron(III)oxide
Give two conditions needed for rusting of iron to occur.
Two conditions needed for rusting of iron to occur are water and oxygen.
Give two examples of barrier methods that can prevent rusting.
Examples of barrier methods that can prevent rusting are:
Painting
Greasing
Electroplating
Which nail will rust?
Nail A will rust because it is exposed to oxygen AND water.
True or False?
Rusting weakens the structure and integrity of iron over time.
True.
Rusting weakens the structure and integrity of iron over time as more iron is lost.
True or false?
Galvanising is the method of coating iron with a layer of lead.
False.
Galvanising is the method of coating iron with a layer of zinc.
What is meant by sacrificial protection?
Sacrificial protection is when a more reactive metal is intentionally allowed to corrode to protect the metal it is covering.
Why is zinc used to protect iron from corrosion?
Zinc is used to protect iron from corrosion because it is more reactive than iron so will react more readily with oxygen.
True or false?
A metal less reactive than iron can be used for galvanising.
False.
A metal more reactive than iron can be used for galvanising.
What is an alloy?
An alloy is a mixture of metals, where the metals are mixed together physically but are not chemically combined.
True or False?
Alloys can be made from metals mixed with non-metals.
True.
Alloys can also be made from metals mixed with non-metals such as carbon.
Describe the structure of an alloy.
Alloys contain atoms of different sizes which distort the regular arrangement of atoms.
What is the cause of increased hardness and strength in alloys?
The increased hardness and strength of an alloy is caused by the different size atoms which distort the regular arrangements of atoms, preventing the layers from sliding over each other easily.
State an advantage of using alloys over pure metals.
Advantages of using alloys over pure metals are:
Greater strength
Greater hardness
Increased resistance to corrosion
Increased resistance to extreme temperatures
True or False?
Alloys are chemically combined mixtures of metals.
False.
Alloys are physical mixtures of metals, where the metals are not chemically combined.
How do properties of alloys differ from pure metals?
Alloys often have greater strength / hardness, or resistance to corrosion / extreme temperatures compared to pure metals.
Give one use of stainless steel.
Uses of stainless steel include:
Cutlery
Sinks
Chemical plants
Explain why low carbon steel can be used to make car bodies.
Low carbon steel can be used to make car bodies because it is soft and malleable.
Name the two main elements in steel alloys.
The two main elements in steel alloys are iron and carbon.
True or false?
Brass is an alloy of copper and tin.
False.
Brass is an alloy of copper and zinc.
Name the two metals that bronze is an alloy of.
Bronze is an alloy of copper and tin.
Why is high carbon steel used in cutting tools?
High carbon steel is used to make cutting tools because it is very hard.
True or false?
Carats are used to express the purity of gold jewellery.
True.
Carats are used to express the purity of gold jewellery.
Why is pure gold not used to make jewellery?
Pure gold is not used to make jewellery because it is too soft.
Why do thermosetting polymers have high melting points?
Thermosetting polymers have high melting points because there are strong cross-links between polymer chains that need lots of energy to overcome.
Name the monomer used to produce high density and low density poly(ethene).
The monomer used to produce high density and low density poly(ethene) is ethene.
Why do high density and low density poly(ethene) have different properties?
High density and low density poly(ethene) have different properties because they are made under different conditions.
The properties of a polymer depend on which two factors?
The properties of a polymer depends on:
The monomers they are made from
The conditions under which they are made
Describe the structure of a thermosoftening polymer.
A thermosoftening polymer consists of individual, tangled chains with no cross-links between them.
True or False?
Thermosoftening polymers can be melted and remoulded to form different shapes.
True.
Thermosoftening polymers can be melted and remoulded to form different shapes.
Name the two components of a composite.
Two components of a composite are:
Reinforcement
Matrix
True or False?
In a composite, the matrix is surrounded by a reinforcement.
False.
In a composite, the reinforcement is surrounded by a matrix.
Name the reinforcement and matrix used to make concrete.
The reinforcement and matrix used to make concrete are: 0
Reinforcement: Aggregate (sand and gravel)
Matrix: Cement
True or False?
The matrix in carbon fibres is a polymer.
True.
The matrix in carbon fibres is a polymer.
True or False?
Wood is a natural composite.
True.
Wood is a natural composite.
Give two examples of composites.
Examples of composites include:
Concrete
Fibreglass
Carbon fibre
Wood
How is soda-lime glass made?
Soda-lime glass is made by heating a mixture of sand, sodium carbonate and limestone.
True or False?
Borosilicate glass has a lower melting point than soda-lime glass.
False.
Borosilicate glass has a higher melting point than soda-lime glass.
Describe how clay ceramics, such as bricks, are made.
Clay ceramics are made by shaping / moulding wet clay and then heating them in a furnace.