Alkenes

Alkanes and alkenes are hydrocarbons.

Hydrocarbon molecules are made up of hydrogen and carbon atoms only.

An alkene has the formula C₃H₆

Which alkene has the formula C₃H₆?

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How many atoms are there in a molecule of C₃H₆?

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Which is a use of C₃H₆?

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The percentage (%) by mass of each element in a molecule of C₃H₆ is:

hydrogen 14%

carbon 86%.

Figure 1 shows the percentage by mass of hydrogen in a molecule of C₃H₆

Complete Figure 1.

You should:

• complete the y-axis scale

• plot the percentage by mass of carbon as a bar

• label the bar plotted for carbon.

Alkanes can be cracked to produce alkenes and smaller alkane molecules.

Describe a test for alkenes.

Give the result of the test.

C₁₀H₂₂ can be cracked to produce C₃H₆ and an alkane.

Complete the equation for the reaction.

Complete the sentence.

Choose the answer from the box.

ceramics fertilisers fuels

High temperatures between 450 °C and 750 °C are used in cracking reactions.

Which statement describes the molecules at 750 °C compared with the molecules at 450 °C?

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How does the rate of reaction at 750 °C compare with the rate of reaction at 450 °C?

This question is about unsaturated hydrocarbons.

Table 6 shows the boiling points of some unsaturated hydrocarbons.

Estimate the boiling point X in Table 6.

C₂H₄ reacts with water vapour (steam).

Name the compound produced when C₂H₄ reacts with water vapour.

C₄H₈ reacts with chlorine (Cl₂).

Describe the test for chlorine.

Give the result of the test.

Which is the displayed formula of the organic compound produced when C₄H₈ reacts with chlorine?

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Name the unsaturated hydrocarbon with the formula C₃H₆

Why does C₃H₆ tend to burn in air with a smoky flame?

C₃H₆ is a gas at room temperature and pressure.

Calculate the volume of 2.1 g of C₃H₆ at room temperature and pressure.

Give your answer in cm³.

The volume of one mole of any gas at room temperature and pressure is 24 dm³.

Relative atomic masses (A_r): H = 1 C = 12

This question is about addition reactions.

Figure 7 shows the displayed structural formula of ethene.

Complete the sentence.

When bromine water is added to ethene, the bromine water changes from orange to

Chlorine reacts with ethene.

What is used to identify chlorine?

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Which of the following shows the displayed structural formula of the compound produced when chlorine reacts with ethene?

Use Figure 7.

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Chloroethene can be used to produce a polymer called poly(chloroethene).

The displayed structural formula of chloroethene is

Which represents the structure of poly(chloroethene)?

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Ethene can be used to produce another polymer called poly(ethene).

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

Determine the simplest whole number ratio of the density of poly(chloroethene): density of poly(ethene).

Simplest whole number ratio =

Poly(ethene) and poly(chloroethene) can both be used to make pipes.

Suggest why neither polymer is suitable for pipes carrying steam at a temperature of 300 °C.

Use Table 3.

Poly(ethene) and paper can both be used to make shopping bags.

Poly(ethene) is produced from crude oil. Paper is produced from trees.

Suggest one reason why paper is more sustainable than poly(ethene) for making shopping bags.

This question is about monomers and polymers.

Compound A has an alkene functional group and an ester functional group.

Figure 8 represents a molecule of compound A.

Draw a circle around the alkene functional group on Figure 8.

Describe what will be seen when compound A is shaken with bromine water.

Figure 9 is a repeat of Figure 8.

Draw a circle around the ester functional group on Figure 9.

Compound A has the formula C₄H₆O₂

Compound A is flammable.

Write a balanced equation for the complete combustion of compound A.

Many molecules of compound A join together to form polymer B.

Complete the displayed formula equation which represents this reaction.

What type of polymer is polymer B ?

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Polymer B is a polymer which melts when heated.

What word is used to describe polymers which melt when heated?

Explain why some polymers do not melt when heated.

This question is about glass and polymers.

Beakers can be made from borosilicate glass or poly(propene).

Table 1 shows information about materials used to make beakers.

Suggest two reasons why a Bunsen burner should not be used to heat a liquid in a poly(propene) beaker.

Use Table 1.

Poly(propene) beakers are more expensive than borosilicate glass beakers.

Suggest one reason why using poly(propene) beakers instead of borosilicate glass beakers could save money.

Use Table 1.

Which is a raw material used to make borosilicate glass?

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Poly(propene) is produced from propene.

The displayed structural formula of propene is:

Table 2 shows some information about the elements in one molecule of propene.

Complete Table 2.

Which structure is the repeating unit of poly(propene)?

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Poly(propene) is produced in three stages:

• Stage 1: separating large alkane molecules from crude oil

• Stage 2: producing propene molecules from large alkane molecules

• Stage 3: joining many propene molecules together.

Name Stage 1, Stage 2 and Stage 3.

Choose answers from the box.

Stage 1 is.

Stage 2 is.

Stage 3 is.

A molecule of hexene contains a double carbon–carbon bond.

Many hexene molecules join together to form poly(hexene).

Which two words describe a hexene molecule in this process?

Tick (✓) two boxes.

This question is about copper wire and copper compounds.

Copper is used to make electrical wires. Figure 9 shows how copper electrical wire is insulated using an addition polymer called poly(butene).

The addition polymer poly(butene) has the displayed structural formula:

Poly(butene) is produced from the monomer butene. Complete Figure 10 to show the displayed structural formula of butene.

Copper can be obtained by recycling scrap copper wire.

Suggest why poly(butene) insulation must be removed from scrap copper wire before the copper is recycled.

Describe how scrap copper wire can be recycled to make new copper water pipes.

Suggest two reasons why recycling scrap copper is more sustainable than extracting copper from copper ores.

Copper sulfate is a compound of copper. Copper sulfate solution contains copper(II) ions and sulfate ions.

A solution can be added to copper sulfate solution to show the presence of copper(II) ions. Name the solution added. Give the result of the test. Name of solution added

Describe one test to show the presence of sulfate ions in copper sulfate solution. Give the result of the test.

This question is about copper wire and copper compounds.

Copper is used to make electrical wires. Figure 1 shows how copper electrical wire is insulated using an addition polymer called poly(butene).

The addition polymer poly(butene) has the displayed structural formula:

Poly(butene) is produced from the monomer butene. Complete Figure 2 to show the displayed structural formula of butene.

Copper can be obtained by recycling scrap copper wire.

Suggest why poly(butene) insulation must be removed from scrap copper wire before the copper is recycled.

Describe how scrap copper wire can be recycled to make new copper water pipes.

Suggest two reasons why recycling scrap copper is more sustainable than extracting copper from copper ores.

Copper sulfate is a compound of copper. Copper sulfate solution contains copper(II) ions and sulfate ions.

A solution can be added to copper sulfate solution to show the presence of copper(II) ions. Name the solution added. Give the result of the test. Name of solution added

Describe one test to show the presence of sulfate ions in copper sulfate solution. Give the result of the test.

This question is about cycloalkenes. Cycloalkenes are ring-shaped hydrocarbon molecules containing a double carbon-carbon bond. Cycloalkenes react in a similar way to alkenes.

Describe a test for the double carbon-carbon bond in cycloalkene molecules. Give the result of the test.

Table 3 shows the name and formula of three cycloalkenes.

Determine the general formula for cycloalkenes.

Figure 6 shows the displayed structural formula of cyclohexene, C₆H₁₀

Chlorine reacts with cyclohexene to produce a compound with the formula C₆H₁₀Cl₂

Complete Figure 7 to show the displayed structural formula of C₆H₁₀Cl₂

Figure 7

Calculate the percentage by mass of chlorine in a molecule of C₆H₁₀Cl₂ Relative atomic masses (A_r): H = 1 C = 12 Cl = 35.5

This question is about hydrocarbons.

Hexane and hexene are hydrocarbons containing six carbon atoms in each molecule.

Hexane is an alkane and hexene is an alkene.

Draw one line from each hydrocarbon to the formula of that hydrocarbon.

Bromine water is added to hexane and to hexene.

What would be observed when bromine water is added to hexane and to hexene?

Ethane is an alkane and ethene is an alkene.

Figure 8 shows the displayed structural formulae of ethane and of ethene.

Compare ethane with ethene.

You should refer to:

• their structure and bonding

• their reactions.

This question is about hydrocarbons. Hexane and hexene are hydrocarbons containing six carbon atoms in each molecule. Hexane is an alkane and hexene is an alkene.

Draw one line from each hydrocarbon to the formula of that hydrocarbon.

Bromine water is added to hexane and to hexene. What would be observed when bromine water is added to hexane and to hexene?

Ethane is an alkane and ethene is an alkene. Figure 1 shows the displayed structural formulae of ethane and of ethene.

Compare ethane with ethene. You should refer to:

• their structure and bonding

• their reactions.

Figure 3 shows a surfer on a surfboard.

Some surfboards are made from addition polymers.

Addition polymers are made from small alkene molecules.

Which type of bonding is present in small alkene molecules?

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What is the functional group in these small alkene molecules?

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Figure 4 shows the structure of part of an addition polymer surfboard.

The outer surface of the surfboard is coated.

The coating is made from soda-lime glass fibres surrounded by a plastic.

What type of material is the coating of the surfboard?

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Complete the sentence.

Choose answers from the box.

The materials used to make the soda-lime glass fibres are sodium carbonate,

Suggest two reasons why surfboards are coated.

Some surfboards are made from wood.

Table 3 contains information about the materials in an addition polymer surfboard and a wooden surfboard.

Suggest two advantages and two disadvantages of using addition polymers rather than wood to make surfboards.

Use Table 3.

Advantages of addition polymers

Disadvantages of addition polymers

Calculate the volume of wood in a wooden surfboard of mass 5.25 kg

Use Table 3 and the equation: