Crude oil What is it? Where is it found? How can we make use of it?

1
Crude oil What is it?Where is it
found?How can we make use of it?
2

• Crude oil is a fossil fuel, formed millions of
  years
• ago from marine life.
• Drilling for it out of the ground can damage
• habitats and spills can ruin beaches as well as
• harm wildlife.
• However it is a valuable and useful resource that
  
• we all use in many ways.
• Crude oil is a mixture of molecules called
• hydrocarbons as they only contain carbon and
• hydrogen. This mixture is not very useful until
  it is
• separated.

3
Crude oil is separated into different fractions
using a process called fractional distillation.

• The oil is heated then pumped into a
  fractionating tower. The vapours rise through the
  tower and condense back to liquid as they get
  cooler.

4

• Smaller molecules rise higher as they have
  lower boiling points. This is because they have
  weaker intermolecular forces.
• Larger molecules have higher boiling points
  and condense lower down.
• As a consequence, different size molecules
  exit the tower at different places.

Getting cooler
Hottest here, where heated oil enters
5
Notice as the number of carbons (size of
molecules) increases the boiling points increase.
Fraction Boiling Range (oC) Number of carbons
Fuel gas Below 40 1-5
Petrol 40 - 175 5-9
Kerosine 150 - 240 9-14
Diesel 220 - 275 1-17
Smaller molecules are more flammable and less
viscous
Larger molecules are less flammable and more
viscous
6
The mixture, crude oil is not useful, but once
separated each fraction has its uses.
Fuel gas, contains propane and butane (camping
gas)
Smaller molecules
Petrol, used for cars
Naptha Kerosene /paraffin
Diesel
Fuel oil and lubricating oil
larger molecules
Bitumen, used for road surfaces
7
hydrocarbons

• All the fractions obtained from crude oil contain
  
• hydrocarbon compounds.
• They are made only from the elements carbon and
• hydrogen.
• Every carbon has 4 single covalent bonds.
• The smallest hydrocarbon
• is methane, CH4
• It belongs to a group known
• as the alkanes
• These are hydrocarbons
• with single bonds.

8
Displayed formula Alkane Molecular
formula






9






10

• The hydrocarbon molecules in crude oil vary in
• size. The larger the hydrocarbon molecules
• (a) the higher its boiling point
• (b) the less volatile it is
• (c) the less easily it flows (the more viscous it
  is)
• (d) the less easily it ignites (the less
  flammable it is).
• Hydrocarbons with large molecules do not
• make good fuels. There is less demand for
• them than the smaller more useful
• molecules.

11
Cracking

• The fractions that contain smaller
  hydrocarbons are very useful as fuels and there
  is a high demand for them. There is less demand
  for the larger hydrocarbons in fractions lower
  down the fractionating column. These larger
  molecules can be broken cracked into smaller
  molecules to match the demand.
• The conditions for cracking are high temperature
  and a catalyst.

12
Cracking
When the large hydrocarbons are heated with a
catalyst they crack.
Molecules with less hydrogen and a double bond
between the carbons are also formed during
cracking.
However there are not enough hydrogen atoms to
complete the 2 smaller molecules.
13
These hydrocarbons that contain double bonds are
called alkenes.

• The simplest alkene is ethene.
• It has the formula C2H4
• The carbon atoms are joined together by a double
  bond.
• Its displayed formula may be drawn in slightly
  different forms but should always clearly show
  the double bond.

14
Alkenes Molecular formula Displayed formula

• Ethene C2H4 H
  H
• 
  C C
• 
  H H
• Propene C3H6 H
  H H
• 
  C C C H
• 
  H H

15
Saturated or Unsaturated?

• Alkanes are saturated.

• Saturated means full up.

• Every carbon atom has already used all four of
  its bonds to join to four other atoms.
• No other atoms can be added.

• Alkenes are unsaturated.

• They have a double bond that could instead become
  two single bonds. This means that other atoms can
  be added. It is not full up.

16

• Test for Alkenes
• When bromine water is added to an
• alkane nothing happens
• but when bromine is added to an alkene
• the red colour of the bromine disappears.

Bromine water alkene
17
alkane alkene
saturated
unsaturated single bonds
double bond no effect on
discolours bromine water
bromine water product of distillation
product of cracking less reactive
more reactive
18
Break

• Make a molemod creature
• and give it a name.

19
Crude oil What is it?Where is it
found?How can we make use of it?
20

• Crude oil is a fossil fuel, formed millions of
  years
• ago from marine life.
• Drilling for it out of the ground can damage
• habitats and spills can ruin beaches as well as
• harm wildlife.
• However it is a valuable and useful resource that
  
• we all use in many ways.
• Crude oil is a mixture of molecules called
• hydrocarbons as they only contain carbon and
• hydrogen. This mixture is not very useful until
  it is
• separated.

21
Crude oil is separated into different fractions
using a process called fractional distillation.

• The oil is heated then pumped into a
  fractionating tower. The vapours rise through the
  tower and condense back to liquid as they get
  cooler.

22

• Smaller molecules rise higher as they have
  lower boiling points. This is because they have
  weaker intermolecular forces.
• What happens to large molecules and why?
• As a consequence, different size molecules
  exit the tower at different places.

Getting cooler
Hottest here, where heated oil enters
23
What happens to the boiling point as the number
of carbons (size of molecules) increases?
Fraction Boiling Range (oC) Number of carbons
Fuel gas Below 40 1-5
Petrol 40 - 175 5-9
Kerosine 150 - 240 9-14
Diesel 220 - 275 1-17
Smaller molecules are more f and less v
Larger molecules are less f and more
24
The mixture, crude oil is not useful, but once
separated each fraction has its uses.
Fuel gas, contains propane and butane (camping
gas)

Petrol, used for cars
Naptha Kerosene /paraffin
What happens to the size of the molecules as the
fractions get higher?
Diesel
Fuel oil and lubricating oil
Bitumen, used for road surfaces
25
hydrocarbons

• All the fractions obtained from crude oil contain
  
• hydrocarbon compounds.
• They are made only from the elements carbon and
• hydrogen.
• Every carbon has 4 single covalent bonds.
• The smallest hydrocarbon
• is methane, CH4
• It belongs to a group known
• as the alkanes
• These are hydrocarbons
• with single bonds.

26
Displayed formula Alkane Molecular
formula

Sketch the next 2 alkanes and write their formula





27

• The hydrocarbon molecules in crude oil vary in
• size. The larger the hydrocarbon molecules
• (a) the higher its boiling point
• (b) the less volatile it is
• (c) the less easily it flows (the more viscous it
  is)
• (d) the less easily it ignites (the less
  flammable it is).
• Hydrocarbons with large molecules do not
• make good fuels. We say there is less .. for
  them.

28
Cracking

• Cracking is when molecules are broken
  into .. Molecules.
• The conditions for cracking are
• h. .
• and a c..

29
Cracking
When the large hydrocarbons are heated with a
catalyst they crack.
Molecules with less hydrogen and a double bond
between the carbons are also formed during
cracking.
However there are not enough hydrogen atoms to
complete the 2 smaller molecules.
Hydrocarbons with double bonds are known as
alkenes.
30
Alkenes Molecular formula Displayed formula

• Ethene C2H4 H
  H
• 
  C C
• 
  H H
• Propene C3H6 H
  H H
• 
  C C C H
• 
  H H

Draw the answer for ethene on one side of your
board and the answer for propene on the other.
31
Saturated or Unsaturated?

• Alkanes are saturated.

• Saturated means full up.

• Every carbon atom has already used all four of
  its bonds to join to four other atoms.
• No other atoms can be added.

• Alkenes are unsaturated.

• They have a double bond that could instead become
  two single bonds. This means that other atoms can
  be added. It is not full up.

32

• Test for Alkenes
• When bromine water is added to an
• alkane nothing happens
• but when bromine is added to an alkene
• the red colour of the bromine disappears.

Bromine water alkene
33
alkane alkene
saturated
unsaturated single bonds
double bond no effect on
discolours bromine water
bromine water product of distillation
product of cracking Less reactive
more reactive
34
break
35
Crude oil Where is it found?What
problems can its exploitation cause?
36

• Which is a correct statement about crude oil?
• Formed by the decay of dead sea creatures.
• Consist of a mixture of very large molecules.
• Is purified in an oil rig.

37

• Hydrocarbons contain only which two elements?
• CARBON AND HYDROGEN
• CARBON AND OXYGEN
• HYDROGEN AND COPPER

REARRANGE Crude different of
hydrocarbon a sized oil
mixture is molecules.
REARRANGE Crude oil is a mixture of different
sized hydrocarbon molecules.
38

• Which sized molecules rise to the top of the
  tower?
• Do they have lo or high boiling points?
• Do they have strong or weak intermolecular
  forces?

Getting cooler
Hottest here, where heated oil enters
39

• Which is a correct statement about fractional
• distillation?
• Oil is separated into fractions with the same
  size molecule.
• Oil is separated into fractions with the same
  density.
• Oil is separated into fractions with similar size
  molecules.

40

• Which is a correct order for these fractions
  working down from the top of the column?
• Fuel gas, kerosine, petrol, diesel, bitumen.
• Fuel gas, diesel, kerosine, petrol, bitumen.
• Fuel gas, petrol, kerosine, diesel, bitumen.

41

• Which of these is a true statement about the
  changes that occur as hydrocarbon molecules get
  larger?
• Boiling point decreases.
• Viscosity increases.
• Flammability increases.

Give one other factor that changes as the
molecules get larger.
42
Alkanes are hydrocarbons that are ..saturated or
unsaturated?have single or double bonds?
43
Sketch these 2 alkanes and write their formula






44

• Why are smaller hydrocarbons in more demand than
  larger molecules?
• What do we do with large hydrocarbons that are in
  less demand so we can match the demand for the
  smaller molecules?
• Name 2 conditions needed for this process.

45

• Which 2 types of hydrocarbons are produced during
  cracking?
• What is the difference between them?

46
Alkenes Molecular formula Displayed formula

• Butene C4H8 H H
  H H
• 
  C C C C H
• 
  H H H
• Pentene C5H10 H H H
  H H
• 
  C C C C C H
• 
  H H H H

What is the general formula for the alkenes?
CnH????
47

• Which of these is an alkene?
• C6H14
• C4H8
• C12H26
• C102H206

48

• Which is alkene has 5 carbons?
• Propene
• Pentene
• Pectane
• Proptene

49

• What is the molecular formula of Butene?
• C3H6
• C4H8
• C2H4
• C6H12

50

• What do alkanes do to Bromine water?
• Produce layers
• Turn it colourless
• Leave it unchanged

51
alkane alkene
Which of these statements are in the wrong place?
saturated or unsaturated
double bond or single bonds
discolours or no effect on
bromine water bromine water
product of or product of
distillation cracking less
reactive or more reactive