Properties of hydrocarbons

Dodecane is an alkane.

The general formula for alkanes is C_nH_2n+2

A molecule of dodecane has 12 carbon atoms.

Complete the formula of dodecane.

A student investigated the effect of changing the temperature on the viscosity of dodecane.

Figure 4 shows the apparatus.

This is the method used.

1. Add 100 cm³ of dodecane at 25 °C to the cup.

2. Immediately start a timer.

3. Stop the timer when 40 cm³ of dodecane has been collected in the measuring cylinder.

4. Record the time taken.

5. Repeat steps 1 to 4 using dodecane at different temperatures.

The student used a water bath to heat the dodecane.

Suggest one reason why the student used a water bath instead of a Bunsen burner to heat the dodecane.

Give one control variable used in the investigation.

Figure 5 shows the results.

Predict the time taken to collect 40 cm³ of dodecane at 75 °C.

You should extend the line of best fit on Figure 5.

The higher the viscosity, the slower dodecane flows.

Explain how the trend in Figure 5 shows the effect of an increase in temperature on the viscosity of dodecane.

Dodecane is an alkane.

The general formula for alkanes is C_nH_2n+2

A molecule of dodecane has 12 carbon atoms.

Complete the formula of dodecane.

A student investigated the effect of changing the temperature on the viscosity of dodecane.

Figure 1 shows the apparatus.

This is the method used.

1. Add 100 cm³ of dodecane at 25 °C to the cup.

2. Immediately start a timer.

3. Stop the timer when 40 cm³ of dodecane has been collected in the measuring cylinder.

4. Record the time taken.

5. Repeat steps 1 to 4 using dodecane at different temperatures.

The student used a water bath to heat the dodecane.

Suggest one reason why the student used a water bath instead of a Bunsen burner to heat the dodecane.

Give one control variable used in the investigation.

Figure 2 shows the results.

Predict the time taken to collect 40 cm³ of dodecane at 75 °C.

You should extend the line of best fit on Figure 2.

The higher the viscosity, the slower dodecane flows.

Explain how the trend in Figure 2 shows the effect of an increase in temperature on the viscosity of dodecane.

The combustion of fuels is a source of atmospheric pollutants.

Methane is a fuel. Balance the equation for the combustion of methane.

Many fuels are mixtures. Petrol and diesel are mixtures of hydrocarbons. Table 4 shows properties of petrol and of diesel.

Compare the properties of petrol and diesel. Use Table 4.

The gases released when a fuel is burned in car engines may include:

• oxides of nitrogen

• carbon monoxide

• water vapour.

Which chemical element do all these gases contain? Tick (✓) one box.

When diesel burns in car engines, oxides of nitrogen are produced. Where does the nitrogen come from?

When diesel burns, particulates may be produced. What environmental effect do particulates from burning diesel cause?

Carbon monoxide may be produced when diesel burns. Give one reason why carbon monoxide is difficult to detect.

Explain why water vapour and not liquid water is produced when diesel burns.

Sulfur is a common impurity in diesel. Explain why this causes an environmental problem.

The combustion of fuels is a source of atmospheric pollutants.

Methane is a fuel. Balance the equation for the combustion of methane.

Many fuels are mixtures. Petrol and diesel are mixtures of hydrocarbons. Table 1 shows properties of petrol and of diesel.

Compare the properties of petrol and diesel. Use Table 1.

The gases released when a fuel is burned in car engines may include:

• oxides of nitrogen

• carbon monoxide

• water vapour.

Which chemical element do all these gases contain? Tick (✓) one box.

When diesel burns in car engines, oxides of nitrogen are produced. Where does the nitrogen come from?

When diesel burns, particulates may be produced. What environmental effect do particulates from burning diesel cause?

Carbon monoxide may be produced when diesel burns. Give one reason why carbon monoxide is difficult to detect.

Explain why water vapour and not liquid water is produced when diesel burns.

Sulfur is a common impurity in diesel. Explain why this causes an environmental problem.

This question is about hydrocarbons.

Figure 9 shows a hydrocarbon.

Complete the formula for the hydrocarbon shown in Figure 9.

What is the name of the hydrocarbon in Figure 9 ?

Which homologous series does the hydrocarbon in Figure 9 belong to?

30 g of another hydrocarbon contains 24 g of carbon.

Which calculation gives the percentage of carbon in the hydrocarbon?

Tick (✓) one box.

Table 3 shows boiling points of some hydrocarbons.

Describe how the boiling points change as the number of carbon atoms in the hydrocarbon increases.

Hydrocarbons can be cracked.

Give one condition used to crack hydrocarbons.

Balance the equation for the cracking of C₆H₁₄

Give one reason why hydrocarbons are cracked.

Window frames can be manufactured from wood or plastic.

Table 4 shows the results of a life cycle assessment (LCA) for making one wooden and one plastic window frame.

Both window frames are the same size.

Give three advantages of using wood instead of plastic in the manufacture of window frames.

Advantage of wood 1

Advantage of wood 2

Advantage of wood 3

Crude oil is a resource found in rocks. Most of the compounds in crude oil are hydrocarbons.

Complete the sentence.

Crude oil is formed by the decomposition of

Alkanes are hydrocarbons. Give the name of the alkane molecule that has three carbon atoms.

Figure 7 shows two alkane molecules.

Table 4 shows the melting points and boiling points of methane and hexane.

Compare the structure and properties of methane and hexane.

Hydrocarbons are cracked to produce more useful alkanes and alkenes.

Decane (C₁₀H₂₂) is cracked to produce two products. Complete the equation for the reaction.

C₂H₄ is an alkene. What is the test for alkenes? Give the result of the test if an alkene is present.

Crude oil is a resource found in rocks.

Most of the compounds in crude oil are hydrocarbons.

Complete the sentence.

Crude oil is formed by the decomposition of

Alkanes are hydrocarbons.

Give the name of the alkane molecule that has three carbon atoms.

Figure 3 shows two alkane molecules.

Table 2 shows the melting points and boiling points of methane and hexane.

Compare the structure and properties of methane and hexane.

Hydrocarbons are cracked to produce more useful alkanes and alkenes.

Decane (C₁₀H₂₂) is cracked to produce two products.

Complete the equation for the reaction.

C₂H₄ is an alkene.

What is the test for alkenes?

Give the result of the test if an alkene is present.

This question is about the Earth’s resources.

When most fuels burn carbon dioxide is produced.

Balance the equation for the combustion of propane.

Describe the test for carbon dioxide. Give the result of the test.

Propane can be cracked to produce propene and hydrogen. Complete the symbol equation for the reaction.

Describe the test for hydrogen. Give the result of the test.

Propene is an alkene. Describe the test for alkenes. Give the colour change in the test.

This question is about the Earth’s resources.

When most fuels burn carbon dioxide is produced.

Balance the equation for the combustion of propane.

Describe the test for carbon dioxide. Give the result of the test.

Propane can be cracked to produce propene and hydrogen. Complete the symbol equation for the reaction.

Describe the test for hydrogen. Give the result of the test.

Propene is an alkene. Describe the test for alkenes. Give the colour change in the test.

This question is about crude oil and alkanes.

Describe how crude oil is formed.

Describe how crude oil is separated into fractions by fractional distillation.

Table 2 shows the boiling points of three alkanes.

What is the general formula for alkanes?

Explain the trend in the boiling points of the alkanes.

A student investigated one property of the alkanes C₅H₁₂, C₁₀H₂₂ and C₁₅H₃₂ This is the method used.

1. Pour 20 cm³ of C₅H₁₂ into a separating funnel.

2. Open the tap of the separating funnel and start a timer.

3. Stop the timer when the level of C₅H₁₂ reaches line X.

4. Repeat steps 1 to 3 with C₁₀H₂₂ and C₁₅H₃₂

Figure 5 shows the apparatus used.

The level of C₅H₁₂ takes 6.4 seconds to reach line X. Predict the trend in times for the other two alkanes. Give one reason for your answer.

Large hydrocarbon molecules can be cracked to produce smaller, more useful molecules.

Alkanes and alkenes are produced when hydrocarbons are cracked.

Give two conditions used for cracking.

Butane (C₄H₁₀) is an alkane.

Figure 5 shows part of the displayed structural formula of butane.

Complete the displayed structural formula of butane in Figure 5.

Butane burns in oxygen.

Complete the word equation for the complete combustion of butane.

Ethene is an alkene.

Give a test for alkenes.

Give the result of the test if an alkene is present.

Each year many tonnes of crude oil are extracted from the Earth.

It took millions of years for the crude oil to be formed.

What do we call development that meets the needs of current generations without compromising the resources for future generations?

Tick (✓) one box.

Crude oil is a mixture of hydrocarbons.

The hydrocarbons in crude oil are separated into fractions by fractional distillation.

Figure 13 shows a fractional distillation column.

Crude oil vapour passes up the column.

Complete the sentence.

Choose the answer from the box.

Why do the fractions separate?

Tick one box.

Most of the hydrocarbons in crude oil are alkanes.

Figure 14 represents an alkane molecule.

Name the alkane.

Methane (CH₄) is an alkane.

What is the general formula for alkanes?

Tick one box.

Alkanes burn in oxygen.

Balance the equation for methane burning.

Ethene is an alkene.

Which reagent is used to test for alkenes?

Tick one box.

Table 6 shows data from a life cycle assessment (LCA) for the disposal of 10 000 biodegradable plastic bags.

Why are life cycle assessments (LCA) done?

Compare the two methods for the disposal of biodegradable plastic bags.

Use information from Table 6