1.1. Alkanes and alkenes are both series of hydrocarbons.

i) Explain the term hydrocarbon. 

[1]

ii) What is the difference between these two series of hydrocarbons? 

[2]

1.2. Alkenes and simpler alkanes are made from long-chain alkanes by cracking.

Complete the following equation for the cracking of the alkane C₂₀H₄₂.

C₂₀H₄₂ → 2C₄H₈ + 2C₂H₄ + ...............

1.3. Alkenes such as butene and ethene are more reactive than alkanes.

Alkenes are used in the petrochemical industry to make a range of products, which includes polymers and alcohols. 

i) Dibromoethane is used as a pesticide. Complete the equation for its preparation from ethene.

+ Br2 →

[1]

ii) The structural formula of a poly(alkene) is given below.

 Deduce the structural formula of its monomer. 

[2]

iii) How is butanol made from butene, CH₃–CH₂–CH=CH₂? Include an equation in your answer.

[2]

iv) Cracking changes alkanes into alkenes. How could an alkene be converted into an alkane? Include an equation in your answer. 

[2]

1.4. 20c m³ of a hydrocarbon was burnt in 175 cm³ of oxygen. After cooling, the volume of the remaining gases was 125 cm³. The addition of aqueous sodium hydroxide removed carbon dioxide leaving 25 cm³ of unreacted oxygen.

i) volume of oxygen used = .......... cm³ 

[1]

ii) volume of carbon dioxide formed = .......... cm³  

[1]

iii) Deduce the formula of the hydrocarbon and the balanced equation for the reaction. 

[2]