Exam code: 5070
Many compounds have important uses.
The table compares the reactions of four metals with steam.
metal | reaction with steam |
copper | does not react |
magnesium | reacts rapidly |
sodium | reacts explosively |
zinc | reacts slowly when warmed |
Put the four metals in order of their reactivity.
Put the least reactive metal first.
Rust contains hydrated iron(III) oxide.
Describe and explain one method of preventing iron from rusting.
Was this exam question helpful?
Iron and steel objects rust when they are left outdoors.
State the two conditions required for iron to rust.
Name the compound formed when iron rusts.
State two barrier methods used to prevent iron from rusting.
Was this exam question helpful?
Iron can be galvanised to protect it from rusting.
Name the metal used to galvanise iron.
State the two ways in which galvanising protects iron from rusting.
Give one use of sacrificial protection.
Was this exam question helpful?
The table shows four ways of protecting iron and steel objects from rusting.
Complete the table by stating whether each method protects the iron by acting as a barrier, by sacrificial protection, or by both.
method | type of protection |
|---|---|
painting a garden gate | |
coating a steel food can with tin | |
bolting magnesium blocks to an underground steel pipe | |
coating a steel bucket with zinc |
Name the process in which iron or steel is coated with zinc.
The underground steel pipe is protected with blocks of magnesium rather than by painting.
Suggest why.
Was this exam question helpful?
A garden gate is made of iron and is painted.
Explain how painting prevents the gate from rusting.
The paint on the gate is scratched, exposing the iron underneath.
State what happens to the iron at the scratch.
Bicycle chains are made of steel. They are protected with grease rather than paint.
Suggest why grease is used instead of paint.
Was this exam question helpful?
Rusting of steel can be prevented by coating the steel with a layer of zinc.
Explain, in terms of electron transfer, why steel does not rust even if the layer of zinc is scratched so that the steel is exposed to air and water.
When a sample of steel is added to dilute hydrochloric acid, an aqueous solution of iron(II) chloride, FeCl2, is formed.
When a sample of rust is added to dilute hydrochloric acid, an aqueous solution of iron(III) chloride, FeCl3, is formed.
i) Aqueous sodium hydroxide is added to the solutions of iron(II) chloride and iron(III) chloride.
Complete the table below, showing the observations you would expect to make.
| Iron(II) chloride solution | Iron(III) chloride solution |
Aqueous sodium hydroxide |
|
|
[2]
Solutions of iron(II) chloride and iron(III) chloride were added to solutions of potassium iodide and acidified potassium manganate(VII). The results are shown in the table.
| Iron(II) chloride solution | Iron(III) chloride solution |
Potassium | No change | Solution turns |
Acidified potassium | Solution turns | No change |
ii) What types of substance cause potassium iodide solution to turn from colourless to brown?
[1]
iii) What types of substance cause acidified potassium manganate(VII) solution to turn from purple to colourless?
[1]
iv) Which ion in iron(III) chloride solution causes potassium iodide solution to turn from colourless to brown?
[1]
v) Which ion in iron(II) chloride solution causes acidified potassium manganate(VII) solution to turn from purple to colourless?
[1]
Was this exam question helpful?
Steel is an alloy made from impure iron.
Both iron and steel rust. The formula for rust is Fe2O3.2H2O. It is hydrated iron(III) oxide.
i) Name the two substances that must be present for rusting to occur.
[2]
ii) Painting and coating with grease are two methods of preventing iron or steel from rusting. Give two other methods.
[2]
i) Name a reagent that can reduce iron(III) oxide to iron.
[1]
ii) Write a symbol equation for the reduction of iron(III) oxide, Fe2O3, to iron.
[2]
i) Calculate the mass of one mole of Fe2O3.2H2O.
[1]
ii) Use your answer to (i) to calculate the percentage of iron in rust.
[2]
Iron from the blast furnace is impure. Two of the impurities are carbon and silicon. These are removed by blowing oxygen through the molten iron and adding calcium oxide.
i) Explain how the addition of oxygen removes carbon.
[1]
ii) Explain how the addition of oxygen and calcium oxide removes silicon.
[2]
Was this exam question helpful?
Steel food cans are coated with a thin layer of tin.
State the two substances that must both be present for the steel to rust.
State how the layer of tin protects the steel from rusting.
The tin coating on a can is scratched, exposing the steel underneath.
Explain why the steel now rusts.
A steel bucket is coated with zinc instead of tin. The zinc coating is also scratched, exposing the steel.
Explain why the steel in the bucket does not rust.
The layer of tin on a food can is much thinner than the layer of zinc on a bucket.
Suggest why a thin coating is suitable for a food can but would not be suitable for a bucket.
Was this exam question helpful?
Different iron and steel objects are protected from rusting in different ways.
A garden gate is made of iron and can be reached easily.
Name a suitable method of protecting the gate from rusting.
Explain how the method you named in part (a) protects the gate from rusting.
The steel hull of a ship spends months at a time in sea water and cannot be repainted while the ship is at sea.
Name a suitable method of protecting the hull from rusting.
Explain why this method is more suitable than painting for the hull of a ship.
Was this exam question helpful?
Methods of protecting iron and steel from rusting do not last forever.
Blocks of zinc bolted to the hull of a ship have to be replaced every few years.
Explain why.
A painted steel bridge has to be repainted every few years.
Explain why.
Give one advantage of using sacrificial protection rather than painting on a structure that is difficult to reach.
The zinc blocks on a ship's hull are inspected each year.
State two things the inspection should check.
Most ships' hulls are painted as well as having zinc blocks fitted.
Suggest why.
Was this exam question helpful?
This question is about alloys.
Brass is an alloy which contains zinc.
i) Name the other metal in brass.
[1]
ii) Suggest two reasons why an alloy such as brass is preferred to either of its constituent metals.
[2]
In an experiment to investigate the rate of rusting of steel, three pieces of steel were used.
One piece of steel was completely coated with copper, one piece completely coated with zinc and the third piece was left uncoated. All three pieces were left exposed to the atmosphere.
i) Explain why the uncoated piece started to rust.
[1]
ii) The coating on both of the other two pieces was scratched, exposing the steel.
The piece of steel coated with zinc still did not rust but the copper-coated piece of steel rusted very rapidly.
Explain these observations in terms of the formation of ions and the transfer of electrons.
[4]
Was this exam question helpful?
Part of the reactivity series is shown, with the most reactive metal first.
magnesium, aluminium, zinc, iron, copper, silver
A student has samples of magnesium, aluminium, copper and silver. The student wants to give sacrificial protection to an iron object.
State the two metals, from the four, that could give sacrificial protection to iron.
Explain, in terms of electron loss, why magnesium and aluminium would give sacrificial protection to iron.
Explain why neither copper nor silver would give sacrificial protection to iron.
The student wraps a strip of magnesium around an iron nail and leaves it in a tube of water, open to the air, for two weeks.
Describe what the student would see on the nail and on the magnesium after two weeks.
Was this exam question helpful?
An engineer proposes protecting the steel frame of a bridge by bolting sheets of copper to it. The engineer argues that copper hardly corrodes at all, so the steel will be safe.
Explain why bolting copper to the steel will not protect it from rusting.
Explain, in terms of electron loss, why it is the iron and not the copper that corrodes when the two metals are in contact.
Name a metal the engineer could bolt to the bridge that would protect the steel.
Explain how the metal you named in part (c) would protect the steel frame from rusting.
Was this exam question helpful?
The steel support tower of an offshore wind turbine stands in the sea.
State the two conditions that must be present for the steel to rust.
Three parts of the tower are described below.
part of tower | conditions |
|---|---|
A | always below the surface of the water |
B | alternately covered by waves and exposed to the air |
C | always above the water |
Suggest which part of the tower will rust fastest.
Explain your answer.
Once the tower has been installed it cannot be repainted.
Explain why sacrificial protection is more suitable than painting for this tower.
Suggest one difficulty in using sacrificial protection on a structure that stands in the sea.
Was this exam question helpful?
Two identical steel components are stored for one year.
Component X is sealed in a container of dry air.
Component Y is completely covered by water that has been boiled and then cooled, in a sealed container.
After one year, neither component has rusted.
Explain why component X has not rusted.
Explain why component Y has not rusted.
Both containers are opened and left in a damp laboratory.
Suggest which component will begin to rust first.
Explain your answer.
In a factory, the container holding component X has to be opened from time to time so that components can be taken out.
Suggest two changes that would keep the remaining components rust-free.
Was this exam question helpful?