Fuels

Question 1

What are hydrocarbons?

Answer 1

Compounds containing hydrogen and carbon only

Question 2

What are the main families of hydrocarbons?

Answer 2

Alkanes and Alkenes

Question 3

What is crude oil?

Answer 3

A mixture of different hydrocarbon molecules

Question 4

What are fossil fuels?

Answer 4

Finite resources - made so slowly that they are effectively, not being produced anymore
Non-renewable - using them at a rate we can’t replace them
E.g. crude oil and natural gas

Question 5

How is oil and natural gas formed?

Answer 5

Tiny plants and sea animals die and sink to the bottom of the ocean
Sediments bury the remains and cause a lot of pressure
We drill down and collect the oil due to the high pressures ahead by the layers of sediment

ALL OVER MILLIONS OF YEARS

Question 6

What is feedstock?

Answer 6

A raw material used to make other resources

Question 7

What is petrochemical?

Answer 7

A substance made from crude oil I.e. poly(Ethene)

Question 8

What are uses of crude oil?

Answer 8

Fuels for vehicles, aircraft, ships, heating and power stations.

Feedstock or raw materials are used for the petrochemical industry

Question 9

What can be produced from crude oil?

Answer 9

Petrol
Kerosene
Diesel oil

Question 10

What can be produced from natural gas?

Answer 10

Methane

Carbon

Question 11

What needs to be done to crude oil for it to be used as fuel?

Answer 11

Fractionally distilled

Question 12

What is the fractionating column and how does it work?

Answer 12

Column is hottest at bottom and coolest at the top
Larger molecules have higher boiling points so they do not vaporise and fall to the bottom.
The medium sized molecules condense at different temperatures and can be collected at different heights in the column
The smallest molecules do not condense and are collected as gas at the top

Question 13

What is viscosity?

Answer 13

Ability to flow - low viscosity means flows easily

Question 14

Why do different fractions of crude oil have different uses?

Answer 14

They have different properties

Question 15

What is the use for hydrocarbons in the gas fraction?

Answer 15

Because they have a low viscosity and are easy to ignite, they are good to use as fuels

Question 16

What is the use of bitumen (bottom fraction)?

Answer 16

Solid at room temperature and waterproof so it is good for surfacing roofs and roads

Question 17

What is the order of fractions from lowest boiling point to highest?

Answer 17

Gases
Petrol
Kerosene
Diesel oil
Fuel oil
Bitumen

Question 18

Which are the easiest to ignite and have the lowest viscosity?

Answer 18

Gases and levels of ignite decrease down

Question 19

What are the compounds in crude oil fractions mostly?

Answer 19

Alkanes

Question 20

What is the general formula for alkanes?

Answer 20

C H
n 2n + 2

E.g. Ethene = C2 so 2x2 is 4 +2 is 6 so it’s is C2H6

Question 21

What is the order of alkanes?

Answer 21

My - Methane
Evil - Ethane 
Panda - Propane         Top 4 is most important 
Bit - Butane
Phoebe’s - Pentane

Question 22

What alkanes have the highest boiling points?

Answer 22

The higher the number the carbon atoms in each molecule, the higher the boiling point
So, Ethene has a higher boiling point than methane but smaller than propane.

This is because more energy is needed to separate the molecules

Question 23

What happens when alkanes react with excess oxygen?

Answer 23

Produce carbon dioxide and water

Question 24

What are the 5 organic compounds in the homologous series?

Answer 24

Alkanes 
Alkenes
Alcohols
Carboxylic Acids
Esters

Question 25

What are the two main points of Alkanes?

Answer 25

Saturated hydrocarbons

Only have single bonds

Question 26

What are the two main points of Alkenes?

Answer 26

Unsaturated hydrocarbons

Contain ONE double bond

Question 27

What are the two main points of alcohols?

Answer 27

Saturated molecules (not hydrocarbons)
Contain ONE -OH molecule

Question 28

What is combustion?

Answer 28

The burning of fuels in oxygen

Question 29

What is a complete combustion reaction of a hydrocarbon?

Answer 29

Only carbon dioxide and water is produced
Energy is giving out
Burning a fuel in excess oxygen

Question 30

What is the word equation for complete combustion ?

Answer 30

Fuel + oxygen —-> Carbon dioxide + water

Question 31

What is incomplete combustion?

Answer 31

Combustion where there is not enough oxygen present

Question 32

What are the products of incomplete combustion?

Answer 32

Some Carbon Dioxide
Some Water
Soot - dirty and clogs up gas intakes or cause breathing problems if gets in the lungs
Carbon monoxide - toxic and causes death by suffocation (deadly as it is odourless and invisible)

Question 33

How does Carbon monoxide kill in the body?

Answer 33

Oxygen binds to the haemoglobin in red blood cells and is transported round the body before being released.
However, carbon monoxide is the same shape as oxygen so it binds permanently to the haemoglobin so it prevents oxygen from being transported round the body I.e. suffocation

Question 34

How can burning hydrocarbon fuels be a bad problem for the environment?

Answer 34

Many fuels contain traces of sulfur.
When the fuel is burnt, sulfur dioxide is produced.
Sulfur dioxide combines with water to form sulfurous acid which is then oxidised.
It can cause rivers and lakes to pollute and can kill fish and insects

Question 35

How does sulfurous acid as acid rain cause problems?

Answer 35

Causes weathering of buildings (neutralisation)
It is a slow process
Makes soils and water acidic which kills aquatic life
Corrodes metals (MASH)

Question 36

What can oxides of nitrogen cause?

Answer 36

In an engine, the temperature is so high that nitrogen and oxygen can react together
Can cause acid rain
Nitrogen dioxides can cause respiratory problems
Cause smog (smoke and fog) as Nitrogen dioxide reacts in sunlight with other pollutants which forms smog

Question 37

How does Cracking break hydrocarbons?

Answer 37

The long-chain hydrocarbons are heated and break up into smaller, more useful molecules
The vapour after it is heated passes over a catalyst (containing aluminium oxide) and heated to 650 degrees.
The smaller molecules are used for fuel or polymers

Question 38

What is always formed in Cracking?

Answer 38

Ethene and an alkane

Question 39

Why is petrol used as fuel for cars?

Answer 39

Petrol is a liquid at room temperature so large amounts can be stored in a car’s fuel tank and pumped to energy