C9 Crude Oil

Question 1

What is crude oil?

Answer 1

• Finite resource found in rocks

Question 2

What is crude oil the remains of?

Answer 2

A fossil fuel consisting of the remains of ancient biomass consisting mainly of plankton that was buried in mud

Question 3

What is crude oil a mixture of?

Answer 3

a very large number of compounds

Question 4

What is a finite resource?

Answer 4

A resource that cannot be replaced as it is used up

Question 5

What are most of the compounds in crude oil?

Answer 5

Hydrocarbons

Question 6

What is a hydrocarbon?

Answer 6

A compound made up exclusively of hydrogen and carbon atoms

Question 7

What are most of the hydrocarbons in crude oil called?

Answer 7

Alkanes

Question 8

What is an alkene?

Answer 8

• Unsaturated hydrocarbon
• Contains a C=C bond
• General formula for alkenes is: CnH2n+2

Question 9

What is a homologous series?

Answer 9

Series of compounds with same general formula, same functional groups and similar chemical properties

Question 10

What are the first four members of the alkenes?

Answer 10

Methane, ethane, propane,butane

Question 11

How can alkene molecules be represented?

Answer 11

C2H6 or

Question 12

What may the many hydrocarbons in crude oil be separated into?

Answer 12

• Fractions
• Each of which contains molecules with a similar number of carbon atoms, by fractional distillation

Question 13

What can the fractions be processed to create?

Answer 13

Fuels and feedstock for the petrochemical industry

Question 14

What fuels produced by crude oil do we depend on for our modern lifestyle?

Answer 14

• Petrol
• Diesel oil
• Kerosene
• Heavy fuel oil
• Liquefied petroleum gases

Question 15

What useful materials produced by the petrochemical industry does modern life depend on?

Answer 15

• Solvents
• Lubricants
• Polymers
• Detergents

Question 16

Why does the vast array of natural and synthetic carbon compounds occur?

Answer 16

Due to the ability of carbon atoms to form families of similar compounds

Question 17

Describe the combustion of hydrocarbons

Answer 17

• Exothermic reaction occurring when hydrocarbons are reacted with oxygen
• Complete combustion produces carbon dioxide and water (carbon and hydrogen atoms are completely oxidised).
• Incomplete combustion produces carbon or carbon monoxide and water

Question 18

Describe the physical properties of alkanes

Answer 18

• First few in series are gases, then change to liquids, then to solids
• In general, boiling points and viscosity increase as molecules get bigger
• Volatility and flammability decrease as molecules get bigger
• Poor reactivity

Question 19

Explain how fractional distillation of crude oil takes place

Answer 19

• Crude oil is heated and vaporised.
• Vapor rises up the fractionating column (tower).
• The column is hotter at the bottom and cooler at the top.
• Hydrocarbons cool as they go up the column and condense at different heights, as they have different boiling points.
• Large molecules, high boiling points - collected at the bottom.
• Small molecules, low boiling points - collected at the top
• This gives fractions, which can be used in various ways

Question 20

What do some properties of hydrocarbons depend on?

Answer 20

The size of their molecules, including:

• Boiling point
• Viscosity
• Flammability

These properties influence how hydrocarbons are used as fuels

Question 21

Why are short chain molecules that make up the hydrocarbons the most useful?

Answer 21

• Quite small, with relatively few carbon atoms
• These hydrocarbons make good fuels as they ignite easily and burn well
• Less smoky flames than hydrocarbons are made up of larger molecules (very flammable)

Question 22

What do long chain molecules have?

Answer 22

• lots of carbon atoms
• May have branches (side-chains) or form rings

Question 23

What is boiling point?

Answer 23

The temperature at which the liquid boils or the gas condenses

Question 24

How does boiling point change with increasing molecular size?

Answer 24

• Short chain (small molecules): lower boiling point
• Long chain (larger molecules): higher boiling point

Question 25

What is viscosity?

Answer 25

How easily it flows

Question 26

How does viscosity change with increasing molecular size?

Answer 26

• Short chain (small molecule): very runny (low viscosity)
• Long chain (large molecule): thick (high viscosity)

Question 27

What is flammability?

Answer 27

How easily it burns

Question 28

How does flammability change with increasing molecular size?

Answer 28

• Short chain (small molecule): higher flammability
• Long chain (large molecule): lower flammability (smoky flame)

Question 29

What does the combustion of hydrocarbon fuels release?

Answer 29

Energy

Question 30

What happens during combustion?

Answer 30

The carbon and hydrogen in the fuels are oxidised

Question 31

What does the complete combustion of a hydrocarbon produce?

Answer 31

Carbon dioxide and water

Question 32

What is cracking?

Answer 32

When large hydrocarbons are thermally broken down into smaller and useful molecules

Question 33

What methods can cracking be done by?

Answer 33

Various methods including catalytic cracking and steam cracking

Question 34

What type of reaction is cracking?

Answer 34

Thermal decomposition

Question 35

What are the conditions for cracking?

Answer 35

• Reactant heated to vapor
• Passed over a hot catalyst (catalytic cracking) or heated to vapor
• Mixed with steam and heated to high temperatures (steam cracking)

Question 36

How are the products of cracking used?

Answer 36

The products are alkanes and alkenes - used as polymers and starting materials for synthesis

Question 37

What is the test for alkenes?

Answer 37

• Add bromine water
• Colour change occurs from orange to colourless

Question 38

What is more reactive than alkanes?

Answer 38

alkenes

Question 39

What is there high demand for?

Answer 39

Fuels with small molecules

Question 40

What are some of the products of cracking useful as?

Answer 40

Fuels