C9 Crude Oil And Fuels

Question 1

What is crude oil

Answer 1

Crude oil is a finite resource found in rocks. Crude oil is the remains of an ancient biomass consisting mainly of plankton that was buried in mud.

Question 2

What is the composition of crude oil

Answer 2

Crude oil is a mixture of a very large number of compounds. Most of the compounds in crude oil are hydrocarbons, which are molecules made up of hydrogen and carbon atoms only.

Question 3

What is a hydrocarbon

Answer 3

A chemical compound made up of hydrogen ans carbon atoms only

Question 4

What is the general formula for alkanes

Answer 4

C(n) H(2n+2)

Question 5

What are the first 4 members of the alkanes

Answer 5

Methane: C H4
Ethane: C2 H6
Propane: C3 H8
Butane: C4 H10

Question 6

How is crude oil seperated

Answer 6

Fractional distillation

Question 7

Give examples of the uses of fractions dierived from seperating crude oil

Answer 7

Petrol, kerosene, diesel oil, heavy fuel oil, liquified petroleum gas

Question 8

How does the size of the hydrocarbon effect: boiling point, viscosity and flammability

Answer 8

Short chain:
Lower boiling point
Low viscosity
Higher flammability
Long chain: 
Higher boiling point
High viscosity
Lower flammability ( burns with smokier flame )

Question 9

How does fractional distillation work

Answer 9

Crude oil is heated until most has turned to gas
Gases enter fractionating column and liquid drains off
The gases rise and as they rise the temperature cools
Once the gases reach a fraction cool enough, they condense and are drained off
The longer chain condense lower down, shortest chains stay as gases

Question 10

What is the general formula for the complete combustion of hydrocarbons

Answer 10

Hydrocarbon + oxygen = carbon dioxide + water

Question 11

What is cracking?

Answer 11

Longer, less useful hydrocarbons can be split up to form shorter hydrocarbons which are more useful for fuel, it also produces alkenes

Question 12

What are the methods of cracking?

Answer 12

Catalytic cracking:
Vaporised hydrocarbons are passed over a hot powered aluminium oxide catalyst. The longer chains are split apart on the surface of the catalyst
Steam cracking:
Vaporised hydrocarbons are mixed with steam and heated to a high temperature to crack them

Question 13

Shat are the products of cracking

Answer 13

Shorter alkanes

Alkenes

Question 14

What is the test for an alkene

Answer 14

They react with bromine water and turn it from yellow to colourless

Question 15

Why do we crack hydrocarbons

Answer 15

There is a high demand for fuels with small molecules and so some of the products of cracking are useful as fuels.
Alkenes are used to produce polymers and as starting materials for the production of many other chemicals.

Question 16

What are alkenes

Answer 16

Alkenes are hydrocarbons with a double carbon-carbon bond.

Question 17

What is the general formula for an Alkene

Answer 17

CnH2n

Question 18

Why are alkenes unsaturated

Answer 18

Alkene molecules are unsaturated because they contain two fewer hydrogen atoms than the alkane with the same number of carbon atoms.

Question 19

What are the first 4 alkene members

Answer 19

ethene C2H4
propene C3H6
butene C4H8
pentene C5H10