4.1-4.4 Fuels From Crude Oil/Fractional Distillation/Burning Fuels/Cleaner Fuels

Question 1

What is different about different length hydrocarbons?

Answer 1

They have different boiling points

Question 2

Why does crude oil need to be separated to make useful fuels?

Answer 2

Because the compounds in the crude oil burn at different temperatures

Question 3

What are fractions?

Answer 3

Liquids with different boiling points that have been separated from a mixture of liquids

Question 4

How can we separate a mixture of liquids with different boiling points?

Answer 4

Distillation

Question 5

What is the name given to separating crude oil by distillation?

Answer 5

Fractional distillation

Question 6

Define fuel

Answer 6

A substance that releases energy when it’s burned

Question 7

What is crude oil?

Answer 7

A mixture of hydrocarbons that comes directly from the earths crust

Question 8

Describe the:
Boiling point
Volatility
Viscosity 
Flammability
For a short chain hydrocarbon

Answer 8

Boiling point: low
Volatility: high
Viscosity: low
Flammability: high (clean)

Question 9

Describe the:
Boiling point
Volatility
Viscosity 
Flammability
For a long chain hydrocarbon

Answer 9

Boiling point: high
Volatility: low
Viscosity: high
Flammability: low (smokey)

Question 10

What is volatility?

Answer 10

How easy it is to turn into a gas

Question 11

What is viscosity?

Answer 11

How thick/runny it is

Question 12

What are alkanes?

Answer 12

Chains of hydrocarbons without a double bond

Question 13

Give the general formula for alkanes

Answer 13

CnH2n+2

Question 14

Why do we call alkanes saturated hydrocarbons?

Answer 14

They contain as many hydrogen atoms as possible in each molecule

Question 15

Write the molecular formula for ethane

Answer 15

C2H6

Question 16

Write the displayed formula for ethane

Answer 16

H   H
      |     | 
H- C - C- H
      |     |
     H    H

Question 17

Name the numerical order of the hydrocarbons

Answer 17

Meth-
Eth-
Prop-
But-
Pent-

Question 18

Where does fractional distillation take place?

Answer 18

Refineries

Question 19

What does the boiling point of a hydrocarbon depend on?

Answer 19

It’s size

Question 20

How does fractional distillation work?

Answer 20

The crude oil is vaporised and enters a tall fractionating column. The column gets colder the higher up you go. The different length hydrocarbons condense at different points so are then collected at the area where they condensed, as a liquid

Question 21

Where do the longest hydrocarbons end up in the fractionating column?

Answer 21

At the bottom due to their high boiling points

Question 22

Where are the shortest hydrocarbons collected in the fractionating column?

Answer 22

At the top

Question 23

Name the order of the products from fractional distillation in their order from highest to lowest

Answer 23

• bottled gas
• petroleum gas
• naphtha (chemicals)
• kerosene (aircrafts)
• diesel oil (cars, buses)
• fuel oil (ship fuel)
• bitumen (roads)
• residue (roads)

Question 24

What properties would you expect for fractions higher up the fractionating column?

Answer 24

• lower viscosity
• lower boiling points
• higher volatility
• higher flammability

Question 25

What is the complete combustion of hydrocarbons?

Answer 25

When the hydrocarbons react fully with oxygen. They are oxidised to carbon dioxide and water

Question 26

Write a word equation for the complete combustion of ethane

Answer 26

Ethane + oxygen –> carbon dioxide + water

Question 27

What colour does a flame burn if there is complete combustion?

Answer 27

Blue

Question 28

What is the incomplete combustion of hydrocarbons?

Answer 28

When there is not enough oxygen to oxidise the hydrocarbons so some carbon is left over as particulates or carbon monoxide

Question 29

What colour does a flame burn if there is incomplete combustion?

Answer 29

Orange/yellow

Question 30

Name four possible products of the incomplete combustion of a hydrocarbon

Answer 30

• carbon monoxide
• carbon particulates
• unburnt hydrocarbon
• soot
• water

Question 31

Other than hydrocarbons, what type of compounds do most fossil fuels contain?

Answer 31

Sulphur compounds

Question 32

What happens when the sulphur dioxide, from burning fuels, is released into the air?

Answer 32

It causes acid rain

Question 33

Why could nitrogen and oxygen combine to form nitrogen oxides when fuels burn?

Answer 33

There are high temperatures that give them energy to bond together

Question 34

What does nitrogen oxide cause?

Answer 34

Acid does

Question 35

What gas causes particulates?

Answer 35

Carbon monoxide

Question 36

Why might incomplete combustion happen?

Answer 36

Because there is a limited supply of air

Question 37

What do scientists believe causes global dimming?

Answer 37

Particulates

Question 38

Why do particulates cause global dimming?

Answer 38

The particulates, as solid tiny particles, reflect sunlight away from the earth so causes global dimming

Question 39

How is acid rain formed?

Answer 39

Sulphur dioxide and nitrogen oxides react with oxygen in the air and dissolves in water to produce acid rain

Question 40

How can we reduce the amount of sulphur dioxide being produced? Name 2 ways

Answer 40

• remove the sulphur from the fuel before you burn it

* remove sulphur dioxide from the waste gases produced from power stations

Question 41

Name a way we can remove carbon monoxide and nitrogen oxides

Answer 41

Exhaust systems of cars are fitted with catalytic converters

Question 42

How can we prevent particulates from being released?

Answer 42

Filter them so they aren’t released

Question 43

Name 5 products we can obtain from crude oils

Answer 43

• medicine
• fabric
• dye
• plastics
• fuels

Question 44

What does crude oil contain?

Answer 44

Hydrocarbons (and few other compounds)