Crude oil is a mixture of many hydrocarbons which can be separated by fractional distillation to produce a number of fractions with different boiling points.

Explain why hydrocarbons in crude oil have different boiling points.

Outline the key features of fractional distillation that enable crude oil to be separated into fractions.

Explain why, after separation of the fractions, some hydrocarbons are processed further by cracking. 

Decane, C₁₀H₂₂, is an alkane which undergoes cracking to produce two molecules of ethene and one other hydrocarbon.

Write an equation to represent this process. 

Alkanes are a homologous series consisting of saturated molecules.  

Explain the meaning of the term saturated.

The bond angle around each carbon atom in an alkane is 109.5 °.

State and explain the shape around each carbon atom.

Alkanes can react with halogens to form halogenoalkanes.

State the name of the mechanism for this reaction and the condition needed for this reaction to occur.

Methane and bromine can react to form bromomethane.  

Write an equation for the initiation step in this reaction and explain why this is an example of homolytic fission. 

The first equation in the propagation step can be written as shown below.

CH₄ + Br^• ➔ ^•CH₃ + HBr

Write an equation for the second propagation step.

Write an equation for the termination step that results in the formation of ethane, C₂H₆.

The alkanes hexane and 2,2-dimethylbutane are structural isomers with the molecular formula C₆H₁₄.

Draw the skeletal formula of both alkanes.

Explain why 2,2-dimethylbutane has a lower boiling point than hexane.

Write an equation for the complete combustion of hexane. 

State under what conditions incomplete combustion of hexane would occur and write an equation for the reaction.

Nonane is an alkane with the molecular formula C₉H₂₀. It can be used as a fuel in jet engines or cracked to form other products.

State the general formula of the alkanes.

Write an equation to show the complete combustion of nonane. 

A structural isomer of nonane is shown below. 

Give the name of this isomer.

Combustion in jet engines produces pollutants such as NO and CO. 

Explain how these pollutants are formed in internal combustion engines.

Explain why nonane has a higher boiling point than the structural isomer shown in part c).

The table below shows the boiling points of some saturated hydrocarbons.

Explain the meaning of the term hydrocarbon.

State and explain the trend in boiling points shown in the table.

All of the alkanes in the table react with halogens in the presence of ultraviolet light to form halogenoalkanes. 

Name the mechanism for this reaction.

Write two equations for the propagation step of this reaction between hexane, C₆H₁₄, and chlorine. 

Halogenoalkanes have many uses, including as solvents and refrigerants. Bromoethane is formed from the reaction between ethane and bromine in the presence of ultraviolet light.

Write an overall equation for the reaction between ethane and bromine to form bromoethane and one other product. 

Write an equation for the initiation step of this reaction. 

The first equation in the propagation step is shown below.

C₂H₆ + Br^• ➔ ^•C₂H₅ + HBr

Write an equation for the second propagation step.

Write a termination step for this reaction, resulting in the formation of butane.

This question is about the reactions of alkanes.

Alkanes can be used as fuels.

Write a balanced equation for the combustion of octane (C₈H₁₈) in excess oxygen.

Combustion of 45.6 g of octane produced 3.00 moles of CO₂. 

Show that this combustion was incomplete. 

Alkanes react in free radical substitution reactions to form halogenoalkanes. 

Write two propagation steps for the reaction between propane and chlorine to form 2-chloropropane.

Alkanes are saturated hydrocarbons which can be used as fuels.

Outline how fractions of hydrocarbons are obtained by the fractional distillation of crude oil.

Draw the skeletal formula of the alkane 2,3,3-trimethylpentane.

Write an equation for the complete combustion of dodecane. 

Write an equation for the incomplete combustion of C₁₁H₂₄ to produce only H₂O and a toxic gas.

Cracking of an alkane X produces one molecule of propene and one molecule of hexane. 

Deduce the molecular formula of alkane X and write an equation for the cracking process.

State the type of cracking that produces a high proportion of alkenes and give two conditions needed for the process.

The alkane with a molecular formula of C₈H₁₈ has several structural isomers. The structure of one of these isomers is shown below.

Draw the skeletal formula of the isomer shown in the diagram above.

Under certain conditions, C₈H₁₈ reacts with chlorine to form C₈H₁₇Cl. 

Write an equation for the initiation step of this reaction, and state the conditions necessary for the reaction to occur. 

Write an equation for the incomplete combustion of C₈H₁₈ to produce CO as the only carbon-containing product.

Catalytic converters are used to remove the toxic gases NO and CO produced when alkanes burn in combustion engines. 

Write an equation for a reaction between these two gases that occurs in a catalytic converter, and identify a metal that could be used as a catalyst in the reaction.

Free radical substitution reactions can occur between alkanes and halogens in the presence of UV light.

Classify each of the following equations as initiation, propagation or termination by ticking the appropriate box in the table below.

Which of the following equations represents a propagation step in free radical substitution?

Which of the following species would not be formed in the free radical substitution of methane and bromine?