Alkanes Qs

Question 1

Outline the essential features of the fractional distillation of crude oil that allows the crude oil to be seperated into fractions [ 4 marks]

Answer 1

1) Hydrocarbons have different bps

2) bp depends on chain lenth

3) Temp gradient in collumn

4) Higher bp molecules at bottom

Question 2

Suggest the effect contaminated fuel would have on the performance of cars

State how the oil company couldve recognised the problem before petrol was sold [ 2 marks]

Answer 2

1) reduced performance/car less powerful

2) Test it before selling

Question 3

State 2 characteristics of homologous series

Answer 3

• Same functional group
• Chemically similar

Question 4

Crude oil is seperated into fractions by fractional distillation. Outline how different fractions are obtained in this process [ 3 marks]

Answer 4

1) crude oil is vaporised and passed into column

2) Negative temp gradient

3) smaller hydrocarbons condense at top

Question 5

Explain why a thin layer of metals is used in catalytic converters [ 2 marks]

Answer 5

1) Less metal needed

2) produces large surface area