Alloys as useful materials

Cement, concrete and steel are building materials.

Cement contains calcium oxide.

Calcium oxide reacts with water to produce calcium hydroxide.

The equation for the reaction is:

How does the equation show that this reaction is reversible?

The forward reaction is exothermic.

What type of reaction is the reverse reaction?

When excess water is added to 20 g of calcium oxide, 23 kJ of energy is released.

Calculate the energy released when excess water is added to 4 g of calcium oxide.

Pre-stressed concrete contains steel wires within the concrete.

Figure 2 shows the structure of a piece of pre-stressed concrete.

Pre-stressed concrete is a composite.

Draw one line from each component of a composite to a material in pre-stressed concrete.

Component of composite Material in pre-stressed concrete

Which metal do all steels contain?

Bricks are also building materials.

Bricks are ceramics.

Which material is used to make bricks?

Tick () one box.

This question is about gold.

18 carat gold is an alloy containing 75% by mass of gold.

Calculate the mass of gold in a 4 g jewellery ring made from 18 carat gold.

What is the simplest whole-number ratio of the mass of gold: mass of other metals in 18 carat gold?

Tick () one box.

What other two metals may also be present in 18 carat gold?

Tick () two boxes.

Figure 6 represents the structure of 18 carat gold and of 24 carat gold.

Explain why 18 carat gold is harder than 24 carat gold.

Gold is used to make jewellery.

Give one reason why iron is not used to make jewellery.

This question is about materials used to make bicycles.

Figure 6 shows a bicycle.

Table 3 shows information about two materials used to make bicycle frames.

Evaluate the use of aluminium alloy and of bamboo for making bicycle frames.

Use Table 3.

Explain why aluminium alloy bicycle frames do not need protection from corrosion.

Bicycle chains are made from an alloy of iron.

Bicycle chains rust without protection.

Paint is not used to protect bicycle chains from rusting.

Suggest how bicycle chains can be protected from rusting.

Bicycle frames can also be made from a composite of carbon fibres embedded in a polymer resin.

What description is given in this composite to:

the carbon fibre component

the polymer resin component?

This question is about alloys.

Steels are alloys of iron.

Which non-metal element is in all steels?

Tick (✓) one box.

Which two elements other than iron are in stainless steels?

Tick (✓) two boxes.

Give two properties of stainless steels.

Choose answers from the box.

Titanium is used in alloys.

Table 6 shows information about some alloys of titanium.

Calculate the mass of titanium in 5.0 kg of titanium alloy C.

Use Table 6.

Suggest why alloy A and alloy B are used to make aircraft parts.

Use Table 6.

Titanium alloys used for medical purposes must not be toxic.

Suggest why alloy B is not used for medical purposes.

Use Table 6.

This question is about substances used to make windows and window frames.

Figure 2 shows a window.

Glass is made by heating sand with two other materials.

Which two other materials are used to make glass?

Tick (✓) two boxes.

Window frames need to be:

• easy to install

• resistant to damage.

The polymers poly(chloroethene) and HDPE are used to make window frames.

Table 3 shows information about poly(chloroethene) and HDPE.

Suggest one advantage of using poly(chloroethene) compared with HDPE to make window frames.

Give one reason for your answer.

Use Table 3.

Suggest one advantage of using HDPE compared with poly(chloroethene) to make window frames.

Give one reason for your answer.

Use Table 3.

Figure 3 shows the displayed structural formula of poly(chloroethene).

Which monomer is used to make poly(chloroethene)?

Tick (✓) one box.

Chlorine gas is used to produce poly(chloroethene).

Describe a test to identify chlorine gas.

Give the result of the test.

Wood can be used instead of polymers to make window frames.

• Polymers are unreactive.

• Polymers are produced from crude oil.

• Wood breaks down in wet conditions.

• Wood is produced from trees.

Suggest one advantage of using polymers and one advantage of using wood to make window frames.

Advantage of polymers

Advantage of wood

Window frames can also be made from an alloy of aluminium.

6.00 kg of the alloy is used to make a window frame.

Table 4 shows the mass of each element in 6.00 kg of the alloy.

Calculate the percentage of aluminium in 6.00 kg of the alloy.

Why is an alloy used instead of pure aluminium to make window frames?

This question is about copper and alloys of copper. Solders are alloys used to join metals together. Some solders contain copper. Table 4 shows information about three solders, A, B and C.

Solder B and solder C are now used more frequently than solder A for health reasons. Suggest one reason why. Use Table 4.

Suggest one reason why solders B and C have different melting points. Use Table 4.

Copper can be obtained by:

• processing copper ores

• recycling scrap copper.

Suggest three reasons why recycling scrap copper is a more sustainable way of obtaining copper than processing copper ores.

Copper is extracted from low-grade ores by phytomining.

Describe how copper is extracted from low-grade ores by phytomining.

Phytomining has not been widely used to extract copper. Suggest two reasons why.

This question is about alloys.

Bronze and brass are both alloys which contain copper.

Bronze is an alloy of copper and one other metal.

What is the other metal in bronze?

Tick (✓) one box.

Give one use of brass.

Alloys of gold are used to make jewellery.

The proportion of gold in an alloy is measured in carats:

• pure gold is 24 carat

• 50% gold is 12 carat.

Table 3 shows information about two gold rings, A and B.

A and B contain only gold and silver.

Complete Table 3.

Suggest two reasons why alloys of gold are used instead of pure gold to make jewellery.

Steels are alloys of iron.

Spoons are made of stainless steel.

Spoons:

• are washed after use

• must not wear away quickly.

Suggest one reason why stainless steel is suitable for making spoons.

Steel horseshoes are shaped to fit the feet of horses.

Which type of steel is most easily shaped into horseshoes?

Tick (✓) one box.