Corrosion and its prevention

When iron rusts, iron(III) oxide forms.

State two conditions needed for iron to rust.

What is the name of the process used to coat iron with zinc?

What is the correct order of reactivity of these four metals?

Describe a test to show that a solution contains Fe³⁺ ions.

test

result

A sample of iron(III) oxide reacts with excess carbon monoxide.

This is the equation for the reaction.

Explain why this is a redox reaction.

Calculate the minimum mass of iron(III) oxide needed to produce a theoretical yield of 28 g of iron.

[for Fe₂O₃ M_r = 160]

The actual yield of iron from this sample is 21 g.

Calculate the percentage yield of iron.

This question is about the rusting of iron.

Name the two substances needed for iron to rust.

Give the chemical name for rust.

The diagram shows two methods used to prevent iron from rusting.

Method A will work only if the paint coating is not scratched.

Method B will work even if the zinc coating is scratched.

Explain how method A prevents iron from rusting.

Give the name of method B.

Explain how method B prevents iron from rusting even when the zinc coating is scratched.

Structures made of iron can rust.

Name the two substances that cause iron to rust.

State a barrier method that prevents rusting.

Explain how sacrificial protection prevents the rusting of iron.

This question is about the reactions of iron.

Iron rusts when exposed to water and oxygen.

Give the chemical name of the compound that forms when iron rusts.

What type of reaction occurs when iron rusts?

Galvanising is a method used to prevent iron from rusting.

Give the name of the metal used to galvanise iron.

When iron reacts with dilute sulfuric acid, the products are iron(II) sulfate and hydrogen.

Give a chemical equation for the reaction between iron and sulfuric acid.

Give a test for hydrogen.

An excess of iron is added to copper(II) sulfate solution.

Name the type of reaction that occurs.

State the appearance of the solid that forms in the reaction.

Give the reason why no reaction occurs when iron is added to magnesium sulfate solution.

This question is about iron.

One problem with iron is that it rusts.

Name the two substances that iron reacts with when it rusts.

State what type of reaction occurs when iron rusts.

Iron can be prevented from rusting by painting or by coating with zinc.

Explain how painting prevents iron from rusting.

Name the process used to coat iron with zinc.

Explain why a layer of zinc protects iron from rusting, even if the layer of zinc is scratched.

Iron is formed when aluminium reacts with iron(III) oxide.

This is the equation for the reaction.

Explain what this reaction shows about the relative reactivities of aluminium and iron.

Explain which substance acts as an oxidising agent in this reaction.

This question is about gases in the atmosphere.

Name the most abundant gas in the atmosphere.

Name the noble gas that makes up about 1% of the atmosphere.

Name a greenhouse gas in the atmosphere.

A student uses this apparatus to determine the percentage of oxygen in a sample of air.

This is the student’s method.

• measure the initial length of the column of air in the tube

• leave the apparatus for one week

• measure the final length of the column of air

The table shows the student’s results.

State the appearance of the iron wool after one week.

Use the student’s results to show that the percentage of oxygen in the sample of air is approximately 18%.

The actual percentage of oxygen in air is approximately 21%.

Give a reason why the percentage of air calculated from the student’s results is less than 21%.

This question is about gases.

Name the gas that is about 1% of dry air by volume.

Which is the most abundant gas in dry air by volume?

A student uses this apparatus to find the percentage by volume of oxygen in a mixture of oxygen and neon.

This is the student's method.

• measure the initial length of the column of gas in the inverted test tube

• leave the test tube in the beaker for a week

• measure the final length of the column of gas in the test tube

Some of the iron wool rusts.

Give the chemical name for rust.

Give a reason why neon does not react with the iron wool.

The table shows the student’s results.

Use the results to calculate the percentage of oxygen in the mixture of oxygen and neon.

A student uses the reaction between iron and oxygen to find the percentage of oxygen in air.

The diagram shows the apparatus the student uses.

State why the iron powder needs to be wet.

State the colour of the compound formed in the reaction between iron and oxygen.

Give the formula of the compound formed.

Explain the advantage of using iron powder rather than pieces of iron.

The syringe in the diagram shows the reading at the end of the experiment.

Complete table 1 to show the readings on the syringe.

Give both values to the nearest 1 cm³.

The student repeats the experiment and obtains a different set of results.

Table 2 shows these results.

Use the results from table 2 to calculate the percentage by volume of oxygen in the air.

This question is about rusting.

A simplified formula for rust is Fe₂O₃

Name the two substances needed for iron to rust.

Give the chemical name for rust.

What type of reaction occurs in the rusting of iron?

Some iron objects are coated with a layer of zinc to prevent rusting.

Name this type of rust prevention.

Explain how this type of rust prevention continues to protect iron when the layer of zinc is damaged.

Give two other methods used to prevent iron from rusting.

Two substances are needed to cause iron to rust.

Name these two substances.

The box gives the names of some substances.

Use words from the box to answer these questions.

Give the name of a non-metallic element.

Give the name of a compound.

Give the name of the metal that is lowest in the reactivity series.

When iron is left in damp air, rust forms on its surface.

State the chemical name for rust.

Explain how a barrier method prevents rusting.

A student uses this apparatus to find the approximate percentage by volume of oxygen in air.

This is the student’s method.

place a graduated glass tube in a beaker of water

place some damp iron wool and a rubber bung in the top of the tube

record the reading of the water level in the tube

leave the apparatus for a few days

record the reading of the water level again

The diagram shows the readings at the start and at the end of the experiment.

Use the readings to complete the table, giving all values to the nearest 0.5 cm³.

The student uses these results to calculate the percentage by volume of oxygen in air.

Suggest why her calculated value is lower than the expected value.

The student repeats the experiment using the same apparatus.

These are her results for the second experiment.

volume of air in tube at start = 80.0 cm³

reading at start = 20.0

reading at end = 35.5

Use the results to calculate the percentage by volume of oxygen in air.

This question is about metals.

Metals can be arranged in a reactivity series based on their reactions with water and their reactions with dilute hydrochloric acid.

The table shows how four metals, P, Q, R and S, react with water and with dilute hydrochloric acid.

Identify which of the metals P, Q, R or S could be gold.

Suggest why the reaction between metal R and dilute hydrochloric acid was not done.

Use the information in the table to place the metals in order of reactivity from most reactive to least reactive.

Zinc is used to coat iron gates to prevent the iron from rusting.

State the name of this method of preventing iron from rusting.

State another method of preventing iron from rusting.

A mixture of zinc powder and copper(II) oxide is heated.

The chemical equation for the reaction that takes place is

State how the reaction shows that zinc is more reactive than copper.

Explain which substance is the oxidising agent.

The diagram shows two samples of iron, A and B.

Sample B is coated with a thin layer of zinc.

Name the process used to coat iron with zinc.

The two samples of iron are left outside for several weeks.

A brown solid containing hydrated iron(III) oxide forms on sample A.

Give the common name for the brown solid.

Give the names of the two substances that react with the iron to form the brown solid.

Iron can be formed by reacting aluminium powder with iron(III) oxide.

The diagram shows how this reaction can be demonstrated.

When the magnesium fuse is lit, a very exothermic reaction occurs.

State the meaning of the term exothermic.

The equation for the reaction between aluminium and iron(III) oxide is

Explain what this reaction shows about the relative reactivities of aluminium and iron.

Explain why the reaction between aluminium and iron(III) oxide is a redox reaction.