C1.4 Crude Oil and Fuels

Question 1

What is crude oil?

Answer 1

A mixture of many different compounds, mainly made of hydrocarbons

Question 2

Why do different parts of a mixture have different properties?

Answer 2

The different parts of the mixture aren’t chemically bonded - this means different parts of the mixture have different properties e.g. boiling points

Question 3

How is crude oil separated?

Answer 3

With fractional distillation

Question 4

How does the temperature change as you go up a fractionating column?

Answer 4

It’s hottest at the bottom and coldest at the top

Question 5

What is the process of fractional distillation? (2)

Answer 5

1. The crude oil is boiled and is piped into the bottom of the column
2. The different compounds have different boiling points so they condense at different points in the column

Question 6

How does the number of carbon atoms in a hydrocarbon affect it’s boiling point?

Answer 6

The more the carbon atoms, the higher the boiling points

Question 7

How are the different groups of hydrocarbons collected in fractional distillation?

Answer 7

The hydrocarbons that condense together are called fractions, theses are tapped off from the column at the different levels they condense at

Question 8

What are alkanes?

Answer 8

Chains of carbon atoms surrounded by hydrogen atoms - different alkanes have different lengths

Question 9

What are the first 4 alkanes?

Answer 9

Methane CH4, ethane C2H6, propane C3H8* and butane C4H10

Question 10

What is the structure of alkanes?

Answer 10

They contain carbon atoms which form 4 bonds, and hydrogen atoms which form 1 bond, there are no double bonds in alkanes and all the atoms are full saturated

Question 11

What is the general formula for alkanes?

Answer 11

CnH2n+2, n is the number of carbon atoms

Question 12

As you change the length of an alkanes molecule, how is viscosity affected?

Answer 12

The shorter the molecule chain, the less viscous it is

Question 13

As you change the length of an alkanes molecule, how is volatility affected?

Answer 13

The shorter the molecule chain, the more volatile (= turns into gas at a lower temp)

Question 14

As you change the length of an alkanes molecule, how is boiling temperature affected?

Answer 14

The shorter the molecule, the lower its boiling point

Question 15

As you change the length of an alkanes molecule, how is flammability affected?

Answer 15

The shorter the molecules, the more flammable

Question 16

What would a hydrocarbon which is a liquid and can be ignited be used for?

Answer 16

Petrol - car fuel

Question 17

What would a hydrocarbon which is gloopy and viscous be used for?

Answer 17

Lubricating engines or covering roads

Question 18

What is the equation for the complete combustion of a hydrocarbon?

Answer 18

When there is an adequate supply of oxygen:

hydrocarbon + oxygen ==> carbon dioxide + water vapour

Question 19

What is produced when there is partial combustion? (5) What problems are there with one of the products produced?

Answer 19

When there isn’t an adequate supply of oxygen: solid particles of soot are produced, unburnt fuel is released, as well carbon dioxide, water vapour and carbon monoxide (which is poisonous)

Question 20

What is produced when a fuel containing sulphur impurities is burnt?

Answer 20

Sulphur dioxide

Question 21

What does sulphur dioxide cause?

Answer 21

Acid rain

Question 22

What does acid rain cause? (4)

Answer 22

It causes lakes to become acidic so plants and animal die as a result of this, it also kills trees, damages limestone building and ruins stone statues

Question 23

One way of reducing acid rain levels, is by removing the sulphur impurities, what’s wrong with this? (2)

Answer 23

It costs money and requires energy which releases more greenhouse gases

Question 24

Besides removing the sulphur impurities, what other ways can acid rain be reduced? (2)

Answer 24

By disposing of the sulphur dioxide before it’s released into the atmosphere, Acid Gas Scrubbers are used in power stations to remove the gas, but we could just cut down on the use of fossil fuels to prevent acid rain

Question 25

What does an increase in carbon dioxide levels result in?

Answer 25

An increase in the average temperature of the earth - global warming

Question 26

What is global warming?

Answer 26

A type of climate change that causes other types of climate change e.g. changing rainfall patterns

Question 27

What is global dimming?

Answer 27

Due to particles of soot and ash being produced by fossil fuels, the suns rays are reflected instead of reaching earth - the earth is getting darker

Question 28

Why is the theory of global dimming sometimes neglected?

Answer 28

Because the stats showing that global dimming is a thing were considered to be measured using inaccurate equipment

Question 29

What are biofuels?

Answer 29

Fuels made from plant material

Question 30

What are two examples of biofuels?

Answer 30

Ethanol and biodiesel

Question 31

How is ethanol made?

Answer 31

By the fermentation of plants

Question 32

What are the advantages of using ethanol as a fuel? (4)

Answer 32

It is carbon neutral, the process of making ethanol doesn't require much energy, ethanol is renewable as it's made from plants, and growing the crops for ethanol is labour intensive which provides jobs for locals

Question 33

What are the disadvantages of using ethanol as a fuel? (3)

Answer 33

Engines need to be converted before they can work with ethanol, ethanol fuel isn't widely available (compared to petrol where there are petrol stations everywhere), and growing the crops for ethanol can replace farms which are growing food making food prices inc.

Question 34

How is biodiesel made?

Answer 34

It can be produced from vegetable oils such as rapeseed oil and soybean oil

Question 35

What are the advantages of using biodiesel as a fuel? (5)

Answer 35

Carbon neutral, renewable, provides jobs for locals, engines don't need to be converted (as biodiesel can be mixed with diesel and work in a diesel engine), and it produces less sulphur dioxide and particulates than ordinary diesel and petrol

Question 36

What are the disadvantages of using biodiesel as a fuel? (3)

Answer 36

We can't make enough biodiesel to completely replace diesel, it's expensive to make and like ethanol, growing the crops for biodiesel can replace food farms

Question 37

How is hydrogen obtained?

Answer 37

From the electrolysis of water - this requires electrical energy, which can be obtained from renewable sources like solar

Question 38

What are the advantages of using hydrogen as a fuel? (2)

Answer 38

When hydrogen is burnt it combines with air to produce water, so it is very clean, and the hydrogen comes from water which there is an abundance of

Question 39

What are the disadvantages of using hydrogen as a fuel? (4)

Answer 39

An expensive, special engine is needed to use hydrogen as a fuel, hydrogen isn't widely as a fuel, you still need another source of energy to make it, and hydrogen is hard to store as it is extremely flammable