Topic 3 Crude Oil

In a nutshell!

Class revision session

Oil is really important!

• Fuel – petrol, diesel, kerosene

• Plastics – the list just goes on and on!

How was crude oil made? Crude oil is thought to have been made from the remains of marine plants and animals that died millions of years ago.

These remains sank to the bottom of the sea, where they were buried in layers of sand and mud, preventing them from rotting. These layers gradually became sedimentary rock.

Over millions of years the layers of rock built up, increasing the heat and pressure. This caused the remains to be broken down into the molecules that form crude oil and natural gas.

Oil is running out….

• There is only about 50 – 100 years of oil left.

• However the availability of oil will become more and more scarce as it starts to run out.

• The cost will get higher and higher

Hydrocarbons in crude oil Many compounds in crude oil only contain the elements carbon and hydrogen. They are called hydrocarbons.

Most hydrocarbons in crude oil are compounds called alkanes. Alkanes contain a single chain of carbon atoms with hydrogen atoms bonded along the side.

What are alkanes?

Alkanes are a family of hydrocarbon compounds

The simplest alkane is methane. It has the formula CH4.

The second simplest alkane is ethane. It has the formula C2H6.

The third simplest alkane is propane. It has the formula C3H8.

Crude oil itself has no uses – it must first be processed or refined. This is done in an oil refinery.

The first step is to separate compounds in the oil into groups called fractions.

Each fraction contains a mix of compounds with a similar number of carbon atoms.

How can crude oil be made useful?

Watch harry the hydrocarbon 2 (0-5mins)

Fractional distillation of crude oil

1. Oil is heated to about 450 °C and pumped into the bottom of a tall tower called a fractionating column, where it vaporizes.

2. The column is very hot at the bottom but much cooler at the top. As the vaporized oil rises, it cools and condenses.

3. Heavy fractions (containing large molecules) have a high boiling point and condense near the bottom of the column.

4. Lighter fractions (containing small molecules) have a lower boiling point and condense

further up the column.

How does fractional distillation work?

The more carbon atoms in a hydrocarbon molecule, the larger the molecule.

Generally, the

larger a hydrocarbon, the higher its boiling

point.

This is because the intermolecular forces between large molecules are stronger than the intermolecular forces between small molecules.

More energy is needed to break the forces between large molecules, and so the boiling point is higher.

Molecules in crude oil can contain anything from just 1 carbon atom to well over 50.

Alkanes

• Alkanes have a general formula of:

CnH(2n+2)

Example 1: 1 Carbon (2X1) + 2 = 4 1 Carbon, 4 Hydrogens

H

C H H

H

CH4

Structural Formula

Molecular Formula

Alkenes

Example 2: 4 Carbon (4X2) = 8 4 Carbons, 8 Hydrogens C4H8

C C H C

H

H H

H

C

H

H

H Example 3: 6 Carbons (6X2) = 12 6 Carbons, 12 Hydrogens C6H12

C C H C

H

H H

H

C

H

H

C

H

H

C

H

H

H

The Double Bond...

• For GCSE, as long as the double bond is between two carbon atoms it’s position doesn’t matter.

C C H C

H

H H

H

C

H H

H

C C

H

C

H

H H

H

C

H H

H

C C H C

H

H H

H

C

H

H H

This is the same molecule

Saturated vs. unsaturated Alkanes are examples of saturated compounds.

Alkenes are examples of unsaturated compounds.

A saturated compound only contains single covalent bonds between carbon atoms.

An unsaturated compound contains at least one double covalent bond between carbon atoms.

A test to distinguish between saturated and unsaturated compounds is to add red bromine water. In the presence of unsaturated compounds, the red colour disappears.

Naming Alkanes And Alkenes

»Ethane/ene Eat

»Propane/ene Pupils

»Butane/ene But

»Pentane/ene Prefer

»Hexane/ene Hairy

»Heptane/ene Haggis

»Octane/ene or

»Nonane/ene Nice

»Decane/ene Dinners

Testing For Alkenes

• Bromine water (brown) decolourises

Alkene

Testing For Alkenes What Happens?

H

C C

H H

H

Br Br

H

H H

H

Bonding

• Hydrogen is in group 1, it has 1 electron in its outer shell, it needs 2.

• Carbon is in group 4, it has 4 electrons in its outer shell, it needs 8.

C

H

H H

H

When two electrons are shared a single bond is formed.

C

H

H

H

H

C

H

H

H

Bonding

C

H 2 lots of 2 electrons being shared makes a double bond.

2 electrons being shared makes a single bond.

C C H

H

H

H

Bonding

• Bonding between non-metals is covalent.

• The aim is to get a full outer shell of electrons (8 for carbon, 2 for hydrogen) by sharing.

• For each pair (2) electrons that are shared a bond is formed.

Supply and Demand The amount of each type of fraction obtained by fractional distillation does not usually match the amount of each fraction that is needed.

Crude oil often contains more heavier fractions than lighter fractions. Lighter fractions are more useful and therefore more desirable.

The large hydrocarbon molecules in the heavier fractions can be broken down into smaller, more useful, molecules to meet demand for raw materials for fuels and plastics.

Catalytic Cracking Large hydrocarbon molecules can be broken down into smaller molecules using a catalyst. This is called catalytic cracking, and is an example of a thermal decomposition reaction.

The hydrocarbon molecules are heated until they turn into vapour, and then mixed with a catalyst. The molecules break apart, forming smaller alkanes and alkenes.

Alkenes are reactive molecules that are used to make plastics and other chemicals.

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Cracking pentane

+ • propane

• ethene

Cracking Decane Decane from the naphtha fraction can be cracked to form pentane (for use in petrol), propene and ethene.

decane (C10H22)

pentane (C5H12)

propene (C3H6)

ethene (C2H4)

+ +

Cracking Butane Butane can also be cracked in two ways:

butane Methane + Propene

Catalytic Cracking In the Lab Catalytic cracking can be done in the laboratory by heating mineral wool soaked in oil with a catalyst, producing a gas.

What might this gas be?

mineral wool soaked in oil

gaseous product

aluminium oxide catalyst

Catalyst • Cracking requires a temperature of 850oC

• By adding a catalyst, the temperature can be reduced to 750oC

• The catalyst are:

• Silica (silicon dioxide)

• Alumina (aluminium oxide)

• Zeolite (silicate compounds)

• By running industrial sized chemistry at this lower temperature saves a lot of money.

Removing Impurities An important step in refining is removing impurities from fractions. These can damage equipment that uses the fraction, and cause pollution.

One of the most important impurities to remove is sulfur. When burnt, this forms the gas sulfur dioxide, which causes acid rain.

Other impurities that need to be removed include nitrogen, oxygen, water and dissolved metals.

The word ‘polymer’ comes from the Greek words poly (meaning ‘many’) and meros (meaning ‘parts’).

Polymers are very large molecules made when hundreds of monomers join together to form long chains.

Plastics are synthetic polymers that can be shaped by heat or pressure.

What Are Polymers?

Natural and Synthetic Polymers

The monomers in a polymer are joined together by covalent bonds between atoms.

In a covalent bond, each atom shares one or more electron with another atom. The bonds are sometimes shown as sticks.

What Keeps the Chain Together?

covalent bond

Many polymers are formed from alkenes, which are a family of hydrocarbon molecules with the general formula CnH2n.

Alkenes contain at least one double covalent bond between carbon atoms. The double bond makes them very reactive.

What Are Polymers Made From?

The simplest alkene is ethene (C2H4).

The second simplest alkene is propene (C3H6).

double covalent

bond

Addition Polymerization Polyethene (sometimes called polythene) is a polymer made from ethene. The process by which polyethene and other polymers is made is called addition polymerization. This is because many monomers (ethene molecules) are added together.

addition polymerization monomers

polymer

Conditions For Polymerisation

• High temperatures

• High pressure

• Catalyst

Addition polymerisation – poly(ethene)

C C

H

H

H

H

C C

H

H

H

H

C C

H

H

H

H

C C

H

H

H

H

C C

H

H

H

H Five ethene monomer units:

C C

H

H

H

H

C C

H

H

H

H

C C

H

H

H

H

C C

H

H

H

H

C C

H

H

H

H

Two single electrons from the broken double bond

An addition reaction begins when the double bond breaks on each monomer

New carbon to carbon single bonds are formed joining the monomer units together

n

Repeating unit of polymer

The polymer poly(ethene) with five repeating units shown( n=5)

Monomers containing halogen atoms

Name of monomer Molecular formula Full Structural formula

C2H3Cl

C2F4 Tetrafluoroethene

Chloroethene C

H

H H

Cl

C

C

F

F F

F

C

Addition polymerisation- poly(chloroethene)

C C

H

Cl

H

H

C C

H

Cl

H

H

C C

H

Cl

H

H

C C

H

Cl

H

H

C C

H

Cl

H

H Five chloroethene monomer units:

C C

H

Cl

H

H

C C

H

Cl

H

H

C C

H

Cl

H

H

C C

H

Cl

H

H

C C

H

Cl

H

H

Two single electrons from the broken double bond

An addition reaction begins when the double bond breaks on each monomer

New carbon to carbon single bonds are formed joining the monomer units together

n

Repeating unit of polymer

The polymer poly(chloroethene) with five repeating units shown( n=5) The older name for this polymer is polyvinyl chloride and the abbreviated name is PVC

Addition polymerisation- poly(styrene)

C C

H

C6H5

H

H

C C

H

C6H5

H

H

C C

H

C6H5

H

H

C C

H

C6H5

H

H

C C

H

C6H5

H

H Five styrene monomer units:

C C

H

C6H5

H

H

C C

H

C6H5

H

H

C C

H

C6H5

H

H

C C

H

C6H5

H

H

C C

H

C6H5

H

H

Two single electrons from the broken double bond

An addition reaction begins when the double bond breaks on each monomer

New carbon to carbon single bonds are formed joining the monomer units together

n

Repeating unit of polymer

The polymer poly(styrene) with five repeating units shown( n=5)

Drawing polymers – shorthand formulae Polymers contain thousands of molecules, so how can their structures be easily drawn?

Part of the polymer molecule can be drawn:

A better way is to show a shorthand formula:

The ‘n’ means that the polymer contains a very large number of the repeating unit shown in the brackets.

What’s the Polymer? What is the shorthand formula for polypropene?

The monomer is propene (C3H6):

which can be drawn as:

1. Draw two C atoms that were in the double bond with a single covalent bond.

2. Draw the brackets and the ‘n’.

4. Add the atoms that were attached to each C atom of the double bond.

3. Add the links outside the brackets.

polypropene

What’s the Monomer? What is the monomer of polyvinylchloride (PVC)?

1. Draw two C atoms joined with a double covalent bond.

2. Add the atoms attached to each C atom.

3. Draw the brackets and ‘n’.

The equation for the reaction can be drawn as:

Cooked spaghetti is solid when cold, but soft when warm. The strands can slide past each other. It is the same with many polymers.

weak intermolecular forces – these let the chains slide past each other

What do polymer chains and spaghetti have in common? What Are Thermosoftening Plastics?

Plastics made of these polymers are stretchy and have a low melting point. They are called thermosoftening plastics.

Thermosoftening plastics (also called ‘thermoplastics’) do not contain cross-links.

Uses Of Thermosoftening Plastics

This means they are flexible, stretchy and have a low melting point. It also means they can be moulded and shaped after they have been made, many times.

What are some examples of thermoplastics?

polyethene natural rubber

Plastics made of these polymers cannot be stretched, are rigid and have a high melting point. They are called thermosetting plastics (or ‘thermosets’).

strong intermolecular forces (cross-links) – these hold the chains firmly in place

Some polymer chains cannot slide past each other.

What Are Thermosetting Plastics?

Thermosetting plastics contain cross-links. This means that they:

Uses of thermosetting plastics

What type of objects might you make from thermosetting plastics?

are rigid

will break when bent

have a high melting point (they char rather than melt)

must be moulded into shape when they are being made,

In the UK, 3.5 million tonnes of plastic packaging is thrown away each year! There are three ways to dispose of waste plastics:

Each method of disposal has its own advantages and disadvantages.

landfill

incineration (burning)

recycling

Why has the issue of dealing with waste plastic in a cheap and environmentally-friendly way become more important?

How much waste plastic?

Plastic bags are a major source of waste at landfill. British shoppers use over 8 billion of them a year!

Landfill is a convenient method of waste disposal but it is only designed to bury rubbish, not to break it down.

Most plastics are made up of tightly bonded molecules that cannot be decomposed by micro-organisms. These will remain buried at landfill sites for thousands of years without rotting.

The UK has 4,000 landfill sites and it is predicted that the largest of these will become full in less than 5 years.

Plastics And Landfill Sites

Why Don’t Plastics Rot? • Bacteria is responsible for the rotting process.

• They use enzymes to digest.

• Polymers aren’t natural.

• At the moment there are no bacteria with an enzyme to break down the bonds in polymers.

Enzyme

Natural Substrate

Polymer

X

Most plastic products carry a symbol that shows which type of polymer they are made from.

Many plastic items look and/or feel similar to each other but they are actually made from different materials, e.g. margarine tubs (polystyrene) and plant pots (polypropene).

Usually, the only types of plastic to be recycled are PET, PVC and HDPE.

If different polymers are mixed together during recycling, it can reduce the quality and value of the final recycled plastic.

Can I Be Recycled?

Recycling plastic uses less water and energy resources than in producing new plastics, and produces fewer greenhouse gases.

This is because the polymer chains become damaged or contaminated with food or other types of plastic.

Recycling Plastics

One problem with recycling, however, is that is reduces the strength and versatility of the plastic over time.

Incineration

• Material is burned at high temperatures

• By products can include hydrochloric acid and dioxins

• The heat generated can be used to generate electricity

Biodegradable plastics are increasingly being used in carrier bags, bin bags and food packaging.

One of the problems with traditional plastics is that they do not break down when thrown away.

Biodegradable plastics are plastics that can be broken down. They are converted into carbon dioxide, water and minerals by micro-organisms.

Biodegradable plastics, such as polylactide, are plant-based polymers. They are often made from starch that has been modified to become more stable.

Biodegradable Plastics

what can businesses and individuals do to reduce the amount of waste they produce?

Dealing with waste is important, but there are many issues involved:

if more products are made of biodegradable plastics, how will the management of landfill sites change?

Dealing With Waste

how many products could be made from biodegradable plastic?

what will happen to closed landfill sites in future?

When a substance burns, it is said to combust.

A fuel is a substance that reacts with oxygen (combusts) to release useful energy.

Combustion and fuels

Combustion is a reaction between a substance and oxygen that releases heat and light energy.

Plenty of air is needed to provide enough oxygen for a hydrocarbon fuel to burn completely.

oxygen carbon

dioxide hydrocarbon + + water

The blue flame of a gas hob or a Bunsen burner is an example of complete combustion of a hydrocarbon (in this case, natural gas).

Complete combustion of hydrocarbons

Complete combustion of propane Propane is a hydrocarbon used in camping gas. What is the equation for its combustion?

oxygen carbon dioxide

propane + + water

5O2 3CO2 C3H8 + + 4H20

How would the equations change if butane was used?

Products of combustion

Complete combustion of methane Propane is a hydrocarbon used in camping gas. What is the equation for its combustion?

oxygen carbon dioxide

methane + + water

2O2 CO2 CH4 + + 2H20

How would the equations change if butane was used?

Complete combustion of heptane Propane is a hydrocarbon used in camping gas. What is the equation for its combustion?

oxygen carbon dioxide

heptane + + water

8O2 5CO2 C5H12 + + 6H20

How would the equations change if butane was used?

Methane + oxygen carbon monoxide + water

Incomplete combustion is a chemical reaction.

This occurs when not enough oxygen is present.

Incomplete combustion is a chemical reaction.

The products are carbon monoxide and water. Soot can also

be given off.

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Burning Fuels

Lots of oxygen:

Some oxygen:

Little oxygen:

C

H

H

H

H O

O

O O

O H H

O H H

C O

O

Methane Oxygen + Water + Carbon dioxide

Oxygen +

O O

O O

O O

Methane

C

H

H

H

H

C

H

H

H

H

Carbon monoxide

C O

C O

Water +

O H H

O H H

O H H

O H H

C C

H

H

H

H

Methane

O O

Oxygen +

O H H

O H H

Water + Carbon

•Carbon monoxide is a dangerous gas.

•It can cause people to suffocate.

•Carbon monoxide is attracted to the haemoglobin that makes up your red blood cells. This reduces the amount of oxygen they can carry around.

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Explain in your own words how carbon monoxide acts as a poison in your blood.

Try to use keywords: carbon monoxide, combustion, oxygen, red cells

•You can't see it, taste it or smell it but CO can kill quickly without warning.

• According to the HSE statistics around 20 people die from CO poisoning caused by gas appliances and flues that have not been properly installed, maintained or that are

poorly ventilated.

Carbon monoxide

•Levels that do not kill can cause serious harm to health if breathed in over a long period.

•In extreme cases paralysis and brain damage can be caused as a result of prolonged exposure to CO. Increasing

public understanding of the risks of CO poisoning and taking sensible precautions could dramatically reduce this

risk.

Carbon monoxide

What is acid rain? Acid rain is rain, or precipitation, with a pH of 5.6 or lower. It is caused by the pollutants sulfur dioxide and nitric oxides.

Acid rain causes millions of pounds worth of damage to buildings in the UK each year and is also damaging to the natural environment, plants and animals.

Greenhouse gases

The greenhouse effect

What do you think?

Are humans responsible for climate change? Are ALL humans responsible?

What is the evidence?

What is the evidence for climate change?

Is the climate really changing rapidly?

Is human activity causing this climate change?

Data collected by climate scientists can be used to answer two key questions:

They can do this in a number of ways •Glacier monitoring – how much they are melting

•Measuring of CO2 levels – has it gone up?

•Ice cores – looking at CO2 levels thousands of years ago

Stick in this graph. What does it tell us? Why do you think this may have happened?

What could be done in the future?

Iron seeding

Adding iron to the upper levels of the ocean encourages algae growth.

The algae carry out photosynthesis which takes in the extra carbon dioxide

Algal bloom off the coast of the UK and France

Carbon dioxide + water glucose + oxygen

What could be done in the future?

Turning CO2 into hydrocarbons

Using nanotechnology it is possible to convert carbon dioxide into hydrocarbons.

This technology is in its very early stages

Could nanotubes hold the answer?

The Problems With Oil

When we burn oil it releases carbon dioxide which has

environmental effects

We need to find something else!

It is non renewable, once we’ve used it up, it’s gone for good (We think

there is around 40-50 years worth of oil left, however it is expected that we will find more as the polar

ice caps retreat)

Generating electricity

What are better sources of fuels?

Make a list of the alternatives you can

think of…

What do you think?

When some rubbish is buried it breaks down to produce methane

which could be trapped and burnt to make electricity

Biofuels

Are fuels made from plants

Rapeseed is removed from the plant and then crushed to make oil. This oil is then burnt to make fuel.

Sunflower oil wood

Biofuels

Are fuels made from plants

They can be burnt on their own or mixed with normal fuels to make them more ‘GREEN’

• Comes from products of living organisms.

• Carbon neutral – only release as much CO2 as what they made during photosynthesis.

• Helps to reduce global warming.

Biofuels

• Bio-fuels are renewable, they can ‘quickly’ be re-grown.

• Bio-fuels are termed carbon neutral:

• However they still need to be transported around

Bio-fuel crop

Carbon Dioxide

(CO2) Photosynthesis Combustion

(burning)

Biofuels

• Also known as gasohol.

• Found in beer & wine.

• Fermentation of sugar cane.

• Mixed with petrol.

• Reduces the amount of oil needed.

BBC News Player

Biofuels

• What problems may occur when crude oil supplies begin to run out? (2)

State the advantages and disadvantages of using biofuels for energy. (6)

What makes a

good fuel?

What would we have to consider?

• Have to consider how many Joules of energy (J) are produced when the fuel is burnt.

How much energy it releases

• Think about how available the fuel is.

• Can we get hold of it easily?

Availability

• Does it cost a lot to extract?

• Is it expensive to store?

Cost

• Does it produce a lot of toxic products when burnt?

• How dangerous are the toxic products?

• Is the fuel toxic?

• If so how toxic?

Toxicity

• Is it expensive to store?

• Is it easy to store?

• Does it need expensive or hard to get chemicals to keep it save until its used?

How easy is it to store

• Does it use burn?

• Does it need another chemical to use?

• Is it dangerous?

• Is it flammable?

• How easy is it to transfer?

How easy it is to use

• Does it release polluting gases?

• Do the products of burning contribute to the greenhouse effect?

• If so how much?

Pollution

You conducted a CA on the best fuel

• Compare it with this question