Crude Oil

Question 1

How is crude oil formed (6 steps)

Answer 1

From soft remains of sea plants/ animals on the ocean floor

These remains get buried deeper into the soil

Exposed to intense temperatures and pressures

Chemical changes begin to firm crude oil and natural gas

These substance are less dense than water so pass through permeable rock

Eventually they hit impermeable rock and can’t go any further

Question 2

Why does the oil get forced upwards when drilled

Answer 2

Oil and gas are trapped under intense pressures

Question 3

What are hydrocarbons

Answer 3

Compounds that are only naked up of hydrogen and carbon atoms

Question 4

What is a fraction

Answer 4

Fractions are mixtures of substances of similar size and boiling point

Question 5

How does crude oil get separated into fractions (process + 4 steps)

Answer 5

Fractional distillation

Crude oil is heated to become a gas

It enters the bottom of the column where it is hottest

The gases start to rise up the column and cool

The different sized molecules have different boiling points so they condense at different temperatures. So the small molecules with lower boiling points condense at the top and the larger molecules with high boiling points condense at the bottom

Question 6

What is heavy crude oil

Answer 6

Contains more long chain hydrocarbons that are dark and viscous

Question 7

What is light crude oil

Answer 7

Contains more short chain hydrocarbons which is more runny

Question 8

Why is light crude oil more expensive than heavy crude oil

Answer 8

Light crude oil have more useful small hydrocarbons than heavy crude oil

Question 9

Why do short carbon chains have a low boiling point

Answer 9

Smaller, lighter molecules have weaker intermolecular forces between them so need less energy to break them

Question 10

Why do short carbon chains burn with a clean flame

Answer 10

Smaller molecules are able to burn more easily so it can completely combust

Question 11

Why are short carbon chains runny

Answer 11

Smaller molecules can pass over each other easily so

Question 12

Why do long carbon chains have high boiling points

Answer 12

Longer, heavier molecules have stronger intermolecular forces so need lots of energy to break them

Question 13

Why do long carbon chains burn with a sooty flame

Answer 13

Larger molecules burn less easily so there is incomplete combustion

Question 14

Why are long carbon chains viscous

Answer 14

Larger molecules easily become tangled which reduces the runniness of a liquid

Question 15

Why are fossil fuels finite resources

Answer 15

They are limited so will eventually run out

Question 16

What does crude oil consist of

Answer 16

A mixture of hydrocarbons

Question 17

What is the simplest family if hydrocarbons

Answer 17

Alkanes

Question 18

First 6 alkanes

Answer 18

Methane
Ethane
Propane
Butane 
Pentane
Hexane

Question 19

What is the general formula for an alkane

Answer 19

C(n)H(2n+2)

Question 20

Are alkanes saturated or unsaturated… What does this mean

Answer 20

Saturated - it consists of only single bonds

Question 21

What are combustion reactions

Answer 21

Oxidation reactions - adding oxygen

Question 22

What is complete combustion

Answer 22

Occurs when a substance burns with a plentiful supply of oxygen

Question 23

What are the products of complete combustion

Answer 23

Carbon dioxide + water

Question 24

General equation for complete combustion

Answer 24

Substance + oxygen —> carbon dioxide + water (+ energy)

Question 25

If something needs more oxygen to combust what is it more likely to have when it is burning

Answer 25

Black smoke

Question 26

What is incomplete combustion

Answer 26

Occurs when a substance burns where oxygen supply is limited or the hydrocarbon chain is long

Question 27

What are the products of incomplete combustion

Answer 27

Carbon monoxide, carbon and water

Question 28

What is the general formula for incomplete combustion

Answer 28

Substance + oxygen ---> carbon (monoxide) + water

Question 29

What is the problem with the gases being produced during incomplete combustion

Answer 29

The gas produced which is CO attaches to the haemoglobin in he blood which prevents the transport of oxygen and leads to suffocation

Question 30

Why does sulfur dioxide get produced when burning fossil fuels

Answer 30

Fossil fuels contains sulfur , the sulfur reacts with oxygen when burnt

Question 31

Describe sulfur dioxide (4)

Answer 31

Acidic Toxic Soluble Colourless

Question 32

When does sulfur dioxide cause and how does this happen

Answer 32

Causes acid rain As the rain falls it passes the sulfur dioxide in the air and react together to form acid rain

Question 33

Harmful effects of acid rain (3)

Answer 33

Damages trees Polluters rivers Kills animals

Question 34

How can sulfur dioxide be reduced to reduce acid rain | What is this process called

Answer 34

Desulfurisation | Removing the sulfur dioxide in the flue gas by lining chimneys with a base so it reacts with CaO

Question 35

How are nitrogen oxides formed

Answer 35

Nitrogen and oxygen react together under high temperatures of the engine to form nitrogen oxides that go into the air

Question 36

What does nitrogen oxide cause

Answer 36

Acid rain and breathing problems

Question 37

How is carbon dioxide formed

Answer 37

During combustion of hydrocarbon fuels

Question 38

How is carbon dioxide harmful to the environment

Answer 38

It is a greenhouse gas so it absorbs energy causing global warming

Question 39

Effects of global warming (4)

Answer 39

Severe weather events Flooding Sea levels rise Temperatures around the world increase

Question 40

How are particulates formed

Answer 40

Incomplete combustion of a fuel, they are unburnt hydrocarbons

Question 41

What do particulates cause

Answer 41

Global dimming

Question 42

What is global dimming

Answer 42

Unburnt hydrocarbons travel into the atmosphere and reflect back rays of light back into space

Question 43

What are the two main problems of using fossil fuels as an energy source

Answer 43

Emit toxic gases when burnt which is bad for environment Finite resource

Question 44

What are the 3 alternative fuels to fossil fuels

Answer 44

Biodiesel Ethanol Hydrogen

Question 45

Carbon neutral definition

Answer 45

The amount of CO2 released by burning plant material/ biodiesel balance with the amount absorbed during photosynthesis so there is no addition CO2 in the atmosphere

Question 46

Advantages of biodiesel (4)

Answer 46

Renewable source (derive from plant material so is biodegradable) Carbon neutral (less global warming) Burns cleanly in engines (less sulfur dioxide so less acid rain) (less carbon particulates so less global dimming)

Question 47

Disadvantages for biodiesel (2)

Answer 47

Land needs to be used to grow biofuel crops - --> vegetation/ habitats destroyed (they absorb CO2) - --> instead of growing food (famine, increase food prices) Produces nitrogen oxides (breathing problems + acid rain)

Question 48

What is biofuel

Answer 48

A fuel which is derived from plant material

Question 49

How can ethanol be produced for fuel (2)

Answer 49

Fermentation of glucose in plants | Hydration of ethene

Question 50

Why are there not any fuels that are completely carbon neutral

Answer 50

Fossil fuels are used to make fertilisers for growing biofuel crops. The CO2 released from this do not balance with CO2 absorbed during photosynthesis as burning biofuels also produces CO2

Question 51

Advantages of hydrogen (2)

Answer 51

``` Burns cleanly (water) Produces electrical energy ```

Question 52

Disadvantages of hydrogen (2)

Answer 52

Dangerous (explosive) | Gas (hard to store, high pressure cylinders, need constant supply to run fuel cell)