End Of Unit Questions

Question 1

Describe 2 ways that are used to crack hydrocarbons

Answer 1

By heating a mixture of hydrocarbon vapours and steam and passing them over a very high temperature catalyst

Question 2

Sort these into alkanes and alkenes
•C3H6
•C5H12
•C4H10
•C4H8
•C6H14

Answer 2

Alkanes:
•C5H12 (pentane)
•C4H10 (butane)
•C6H14

Alkenes:
•C3H6 (propene)
•C4H8 (butene)

Question 3

Explain what is meant by a polymer

Answer 3

A polymer has very large molecules made from very small molecules called monomers joined together

Question 4

Describe one use of a smart polymer

Answer 4

Shape memory polymer, used in dressings for wounds

Question 5

What does biodegradable mean?

Answer 5

Can be broken down by microorganisms

Question 6

Suggest 3 ways of reducing the problems of plastic rubbish

Answer 6

• use biodegradable polymers
• recycle
• plastics with cornstarch mixed in
• collect litter for disposal

Question 7

Outline the 2 ways ethanol can be made and give an advantage and a disadvantage of each method

Answer 7

Fermentation of sugar with yeast
Ad: renewable source, room temperature means no electricity for heat
Dis: needs to be distilled, slow, batch process

Hydration of ethene with steam
Ad: pure ethanol produced, continuous process, fast
Dis: non renewable, high temps needed

Question 8

Write an equation using displayed formulae showing the bonds for the polymerisation of propene

Answer 8

CH3  H
       |      | 
n    C==C
       |      |
      H     H 

Goes to

( CH3 H )
(    |     |  )
---C--C---
(    |     |  )  n
(   H    H )

Question 9

Write a balanced equation showing the hydration of ethene

Answer 9

C2H4 + H2O –> C2H5OH

Question 10

Complete this equation for cracking a hydrocarbon

C12H26 –> C6H14 + C4H8 + …..

Answer 10

C2H4

Question 11

Give 2 reasons why fractions from crude oil are cracked

Answer 11

• to make alkenes
• to make fuels that are more useful
• to make polymers
• large hydrocarbons are less useful