Unit 2.5 (2) - Crude Oil, Fuels and Organic Chemistry

Question 1

Explain the concept of the fire triangle and what the three things are.

Answer 1

The fire triangle consists of the three things which must be present for a fire to burn: oxygen, fuel and heat. If any one of these is absent or removed, a fire can’t burn.

Question 2

What is cracking in terms of concept and process?

Answer 2

Cracking is the heating up of crude oil fractions to high temperatures in the presence of a catalyst, to cause them to decompose to form smaller hydrocarbons, including an alkene.

Question 3

Why is cracking necessary?

Answer 3

Crude oil often contains too many large hydrocarbon molecules and not enough small ones to meet demand (there is greater demand for smaller hydrocarbons, and alkenes such as ethene which are required for the production of plastics.

Question 4

What is the general formula for alkanes and alkenes?

Answer 4

Alkanes: Hn C2n+2
Alkenes: Hn C2n

Question 5

Define the terms ‘saturated’ and ‘unsaturated’ in terms of hydrocarbons (and to which type of molecule do each of these apply?)

Answer 5

Saturated - contain the maximum amount of hydrogen possible (alkanes)
Unsaturated - do not contain the maximum amount of hydrogen possible (alkenes)

Question 6

What is the result of an addition reaction of an alkene with hydrogen?

Answer 6

It forms an alkene (one atom is added to each of the carbon atoms either side of the C=C double bond)

Question 7

What is the result of an addition reaction of an alkene with bromine water?

Answer 7

A colourless ‘bromoalkane’ is formed (bromine water turns from orange to colourless, which is how it is used to test for an alkene)

Question 8

Define polymerisation

Answer 8

The joining together of small, reactive molecules called monomers to make a larger molecule, a polymer.

Question 9

What results in the reactivity of a monomer

Answer 9

It has a double bond - as polymerisation happens, one of the bonds breaks to allow the monomer to join to another.