4 Crude Oil And Fuels

Question 1

What are alkanes?2

Answer 1

• saturated hydrocarbons

- they contain many hydrogen atoms as possible in their molecules

Question 2

Is crude oil useful straight out the ground?

Answer 2

No, because there are too many substances in it, all with different boiling points

Question 3

What are hydrocarbons?

Answer 3

Compounds containing hydrogen and carbon

Question 4

How can crude oil be separated using distillation?

Answer 4

Distillation separates liquids with different boiling points

Question 5

What makes a fraction useful as a fuel?3

Answer 5

Lighter fractions make fuels as they ignite more easily and burn well, with cleaner flames

Question 6

What does the boiling point of hydrocarbons depend on?

Answer 6

The size of its molecules

Question 7

What is in crude oil?

Answer 7

Crude oil is a mixture of many different compounds

Question 8

How do the number of carbon atoms vary between hydrocarbons?

Answer 8

They don’t there are similar number of carbon atoms

Question 9

Why do different fractions boil at different temperatures?

Answer 9

Their molecules are different sizes

Question 10

What are the products of combustion when we burn fuels in a good supply of air?2

Answer 10

The carbon and hydrogen in the fuel are completely oxidised

They produce carbon dioxide and water

Question 11

What does changing the conditions which hydrocarbon fuels are burnt do?

Answer 11

Changes the products made

Question 12

What are the products of combustion when we burn fuels with a lack of air?2

Answer 12

Poisonous carbon monoxide gas is formed

We also get particulates of carbon and unburnt hydrocarbons especially if the fuel is diesel

Question 13

When we burn fossil fuels what does the sulfur inside of them form?3

Answer 13

A poisonous gas sulfur dioxide
It is acidic
It is bad for the environment and is the cause of acid rain

Question 14

What does a caralytic converter do?

Answer 14

It reduces the carbon monoxide and nitrogen oxides produced by a car engine

Question 15

Name harmful substances that may be produced when fuels burn?3

Answer 15

Sulfur dioxide, nitrogen oxide, carbon monoxide

Question 16

What are biofuels?

Answer 16

Renewable source of energy that could be used to replace fossil fuels

Question 17

What can biofuels be made from?

Answer 17

Vegetable oils

Question 18

Advantages of biodiesel?5

Answer 18

• less harmful to animals and plants than crude oil if spiller
• burns more cleanly
• makes very little sulfur dioxide
• it will become cheaper as supplies of other things run out
• produces useful products

Question 19

Disadvantages of biodiesel?3

Answer 19

• large areas of farmland are needed to produce fuel instead of food
• could destroy habitats
• a perfect temperature needed for use

Question 20

Why are alkanes described as saturated hydrocarbons?

Answer 20

Because they contain as many hydrogen atoms as possible in each molecule and no more hydrogen atoms can be added

Question 21

What are the advantages of using fermentation to make ethanol?

Answer 21

It uses renewable plant material

Question 22

What are the disadvantages of using ethene to make ethanol?

Answer 22

It needs non-renewable crude oil as its raw material

Question 23

How does fractional distillation work?

Answer 23

The fractionating column works continuously
Heated crude oil piped in at the bottom
The vaporised oil rises up the column
The various fractions are constantly tapped off at the different levels where they condense

Question 24

For alkanes the shorter the molecules… The ?

Answer 24

Less viscous (gloopy)
More volatile - lower boiling point 
More flammable

Question 25

Explain the process of fractional distillation?

Answer 25

Crude oil is heated to 350
Most of the compounds in the crude oil evaporate
Any liquids flow down to the bottom of the column and the hot vapours rise up
When the hot vapours rise up the column the vapours cool
When a fraction in the vapours cools to its boiling point, the fraction condenses

Question 26

Why is carbon monoxide produced?

Answer 26

When incomplete combustion occurs of a fuel

Question 27

What is produced when anything burns completely?

Answer 27

Carbon dioxide

Water

Question 28

Where is the crude oil column hottest?

Answer 28

At the top

Question 29

What does unsaturated mean?

Answer 29

Contains a carbon carbon double bond

Question 30

What happens when iodine is added to oil?

Answer 30

Iodine is decolourise D

Question 31

Why does crude oil need to be fractionally distilled?

Answer 31

Is a mixture of hydrocarbons

Question 32

Long chain hydrocarbons tend to have?

Answer 32

High boiling point
Low volatility
High viscosity
Low flammability

Question 33

Properties of short chain hydrocarbons?

Answer 33

Low boiling point
High voltality
Low viscosity
High flammability