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POM 1 Flashcards

1
Q

Define Petroleum (Crude Oil)

A

A mixture of hundreds and thousands of alkanes, ranging from methane up to alkanes with forty or more carbons.
Formed through the burial and compaction of marine organisms, over millions of years.

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2
Q

Why must crude oil be refined?

A

It is a complex mixture and contains varying amounts of sulfur, oxygen and nitrogen

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3
Q

What is catalytic cracking

A

A process used in the petrochemical industry- the decomposition of long chain alkanes into smaller and more useful alkanes and alkenes, using zeolites (catalysts)

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4
Q

what are zeolites

A

Zeolites are porous crystalline silicate materials, with cavities which exist within the structures, thereby increasing their surface area and thus effectiveness.

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5
Q

What are the conditions of catalytic cracking

A

It requires 70 atm, the absence of air-(or a combustion will occur), and temperatures of approximately 450°C-750°.

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6
Q

What is unsaturation

A

double or triple bonds

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7
Q

Name an equation of how ethylene is produced from catalytic cracking

A

C10H22(g) –> C8H18(g) + C2H4(g)

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8
Q

what is steam cracking

A

Stream cracking is a form of thermal cracking in which saturated hydrocarbons are heated with steam (850°C, in the absence of oxygen) to produce lighter alkanes such as ethylene and propylene.

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9
Q

Name an equation of how ethylene is produced from steam cracking

A

C2H6(g) –> C2H4(g) + H2(g)

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10
Q

What are the two impacts of the use of ‘cracking’

A

The demand of smaller alkane fractions can be met.

Allowed for the production of ethylene- a highly useful by-product which as a result opened up secondary industries that increased profits and provided cheap and useful material for society.

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11
Q

Why are alkenes more reactive than alkanes

A

Unlike alkanes, alkenes are unsaturated, as they contain a double bond which readily allows them to undergo addition reactions.

The double bond of alkenes such as ethylene is more unstable than a single bond, and thus breaks relatively easily to bond with other atoms and/or molecules.

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12
Q

Name four addition reactions alkene can undergo with

A

 Hydrogen (with a catalyst such as Pt and Pd)
 Halogens (Cl2 and Br2)
 Hydrohalic acids (HF, HBr, HL)
 Water (with catalysts such as dilute H2So4)

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13
Q

Outline the steps for Bromine Test for Unsaturation (Qualitative Test)

A
  1. Place 10mL of cyclohexane into a test tube.
  2. Add 2mL of bromine water into the test tube with cyclohexane in it.
  3. Repeat this for cyclohexene
  4. Gently shake each test tube to mix the chemicals
  5. Record observations.
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14
Q

Outline the variables for Bromine Test for Unsaturation

A

Independent: hydrocarbon used (double bond)
Dependent: colour change (reactivity)
Controlled: UV light

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15
Q

What are the results of Bromine Test for Unsaturation

A

Br2 reacts with alkene and the Br atoms join across the double bond. As the Br2 reacts away, the colour changes from brown to colourless.
Bromine is non-polar and reacts by adding bromine atoms across the double bond.
Cyclohexene is more reactive than cyclohexane.

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16
Q

In bromine water test for unsaturation, why isnt chlorine used even though it gives the same reaction

A

it is a gas at room temperature (i.e. toxic) and there is no colour change (large amounts are required).

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17
Q

in bromine water test for unsaturation, why is cyclohexane and cyclohexene are chosen as opposed to ethane and ethene

A

ethane and ethene are gas at room temperature

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18
Q

Is the reaction of ethylene and bromine spontaneous or non-spontaneous?

A

spontaneous

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19
Q

What is a monomer

A

o A monomer is a simple compound that can be polymerised

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20
Q

What is a polymer

A

o A polymer is a long chain molecule made up of repeating units.

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21
Q

What is addition polymerisation

A

 Addition polymerisation involves the formation of a polymer by the reaction of unsaturated monomers, without the elimination of atoms.

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22
Q

Draw the structural formula of vinyl chloride and identify a use of it

A

h Cl
C = C
h h
production of PVC and other plastics

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23
Q

Draw the structural formula of Ethanol and identify a use of it

A 
H  H
H-C-C-O-H 
    H  H
-antiseptic 
-solvent
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24
Q

Draw the structural formula of Ethylene glycol and identify a use of it

A 
H  H
H-O-C-C-O-H 
        H  H
-antifreeze
-solvent
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25
Q

Draw the structural formula of Styrene and identify a use of it

A

H (benzene ring)
c = c
H H

  • CD cases
  • Polystyrene, fabricated plastics and synthetic rubber
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26
Q

Draw the structural formula of ethylene dichloride and identify a use of it

A

Cl h
h- C - C -h
h Cl
Plastic wrap

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27
Q

What is a condensation polymer

A

A long chain macromolecule consisting of repeating units formed when dyfunctional monomers combine with the elimination of small molecules such as water.

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28
Q

Does the zigela natta process create HDPE or LDPE

A

HDPE

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29
Q

Does the free radical process create HDPE or LDPE

A

LDPE

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30
Q

what are the conditions for the ziegla natta process?

A

 Temperatures between 70-300 C
 Pressures between 10-80 atm
 Ionic titanium chloride/ triethyl aluminium catalyst (Ziegler- Natta catalyst)

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31
Q

what are the conditions for the free radical polymerisation process

A

 Temperatures 80-300 C
 Pressures between 1000-3000 atm
 Using oxygen containing initiator molecule (e.g. benzoyl peroxide)

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32
Q

In the free radical polymerisation process, outline the initiation process

A

o An initiator molecule symmetrically dissociates (undergoes homlysis) to form two free radicals.
o Next, a free radical attacks the double bond of an alkene
o The double bond opens up and adds ethylene with no byproducts

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33
Q

In the free radical polymerisation process, outline the chain propagation process

A

o The free radical, now on the terminal carbon attacks another monomer
o This repeats in an iterative fashion, resulting in chain growth (propagation)
o Now that all of the atoms in the reactant end up in the polymer chain
 Note how the chain grows from one end only

34
Q

In the free radical polymerisation process, outline the termination process

A

o Eventually, all of the monomer are exhausted
o When this happens, two free radicals combine to form the final polymer chain.
 If all three processes were to occur at the same time, there will be a range of chain lengths, molecular weights in the product.

35
Q

what is a free radical

A

 A free radical is a molecule that contains an unpaired electron
 Free radicals are extremely reactive

36
Q

Name four benefits of the use of models

A

o Provides a physical representation of the type and quantity of atoms involved in a molecule
o Demonstrates the difference between the various bonds in a molecule
o Provides a simple representation to aid understanding
o It allows you to appreciate the three dimensional nature of the process

37
Q

Name three disadvantages of the use of models

A

o Relative sizes of, and distances between the atoms are unrealistic; not to scale and are used to give general ideas
o The dynamic nature of various molecules and their bonds is not shown
o Oversimplifies the model. I.e. when the polymerisation process for polyethylene was modelled with molecular kits, the role of the peroxide initiator was not shown.

38
Q

The properties of polymers are its melting point, mechanical strength and flexibility, what are the four main characteristics in which it is depended on?

A

o Molecular weight and chain length
o Extent of chain branching
o Presence of side groups
o Interactions between chains

39
Q

how does chain length influence the properties of a polymer

A

o The length of the polymer and molecular weight depends upon the number of monomers the polymers contains.
 The melting point and hardness increase with an increase in chain length
 Longer polymers have higher melting points and are harder

40
Q

how does chain branching influence the properties of a polymer in HDPE and LDPE

A

HDPE

o Unbranched chains are able to pack closely in an orderly fashion, forming rigid crystalline solid. Hence allowing enhanced dispersion forces; high MP, harder, more rigid, higher density. E.g. high density polyethylene.
o Unbranched chains are able to align themselves so that they life parallel to each other.

LDPE

o Consists of long chain hydrocarbon chains, but has significant branching.
o Branched polymer chains are unable to form strong intermolecular forces as branching prevents the packing of polymer chains forming an amorphous regions
o The random disorderly arrangement accounts for weaken dispersion forces; softer, lower MP, more flexible and lower density.

o Note: there are crystalline and amorphous regions in all polymers, but for unbranched polymers, there are more crystalline regions than amorphous regions.

41
Q

Name some uses of LDPE

A

plastic bags, squeezy sauce bottles

42
Q

Name of uses of HDPE

A

Freezer bags, cutting boards, garbage bins and buckets

43
Q

What is chain stiffening and give an example.

A

o Chain stiffening involves putting a bulkier side group into a linear chain to reduce its flexibility and increase its rigidity and stiffness.
o For example, in polystyrene, the presence of bulky benzene side group drastically reduces the flexibility of the chain. The bulky benzene groups restrict the ability of the poly backbone to bend. The strands are therefore more linear and can align more closely to form stronger IMF, resulting in a stiffer and more rigid polymer.

44
Q

Name some properties and uses of chloroethene (vinyl chloride)

A

Rigid and flame resistant with additives
Water resistant

Rigid pipes and gutters
Flexible raincoats and shower curtains

45
Q

Name some properties and uses of ethenyl benzene

A

Transparent, rigid
Forms opaque foam when gas is added

CD cases
Heat insulation foams, floatation devices

46
Q

Name some properties and uses of ethenyl benzene

A

Transparent, rigid
Forms opaque foam when gas is added

CD cases
Heat insulation foams, floatation devices

47
Q

Why does petroleum need to be replaced?
1 reason for society
and 1 for environment

A

It is a non-renewable resource and will eventually be depleted. As the availability of petroleum decreases, costs will rise and this will therefore drive the need to replace petroleum as the source of ethylene with another source.
Also 95% of crude oil is used up as fuel, the consumption of fuel products has an enormous impact upon the environment. The burning of fuel can lead to greenhouse gas effect and acid rain

48
Q

what are some reasons against using a alternate resources (in terms of replacing petroleum)

A

o It costs money for research and setup.
 Addition polymers are mostly made of petrochemicals which are currently inexpensive, whereas condensation polymers, particularly biopolymers like Bipol and polylactic acid, are expensive to make
o Addition polymers tend to have better thermal stability, while condensation polymers tend to have poor thermal and UV stability, and are more brittle.

49
Q

What are major factors that need to be considered when researching alternatives to petroleum

A

o They must be a source of hydrocarbons; the building blocks required to make petrochemicals.
o Also it should be cheap, abundant, renewable and chemically/ industrially possible or efficient.

50
Q

What are the main problems of condensation polymers as opposed to currently used addition polymers

A

if a condensation polymer is biodegradable, its properties tend to be poor, and it tends to be expensive.

51
Q

What is a biopolymer

A

a naturally occurring polymer produced by living organisms.

52
Q

What is the bacteria which produces biopol called

A

Cupriavidus necator (previously called Alcaligenes eutrophus)

53
Q

what are the (steps) for the production of biopol

A

o A culture of the bacteria is placed in a suitable medium and fed with appropriate carbon based food so that bacterial growth and proliferation is promoted.
o Restricting nitrogen stresses the bacteria, stops them from multiplying and forces them to produce PHA (up to 80%).
o The bacterial cells are then lysed and the polymer is extracted and purified.

54
Q

State some advantages and disadvantages of biopol

A 
ADV
o	Biodegradable 
o	Biocompatible 
o	Renewable 
o	Thermoplastic 
o	Can be blended with cheaper materials

DISADV

o Expensive to produce
o Low thermal stability
o Brittle
o Processing difficulties

55
Q

Impact of Biopol on society

A

o Positive impact as it has ideal properties for use in surgery (stitches): biocompatible and biodegradable
o Can be used to make biodegradable packaging so trash will not build up causing a waste problem for society

56
Q

Impact of Biopol on the environment

A

o Can be used in conventional plastic applications such as shampoo bottles. When this plastic waste is discarded, it will not persist in the environment for as long as conventional plastics as it can be degraded by microorganisms.
o Made from renewable resources so that pollution associated with extraction of fossil fuel is minimised.

57
Q

What is the evaluation of the use of Biopol

A

o Overall, the use of Biopol is justified; with the rapid depletion of crude oil and the environmental issues that arise from the use of crude oil based polymers, a new alternative that is both renewable and biodegradable must be used and currently, Biopol is one of the most viable biopolymers that meet this criteria.

58
Q

What are the monomers that make up cellulose called

A

beta glucose

59
Q

what is cellulose used for?

A

o It is used in paper, cellophane, pharmaceutical fillers and other manufacturing areas.
o It is an important source of fibre in the human diet

60
Q

if alpha glucosed is polymerised, what is produced?

A

starch

61
Q

how is cellulose made?

A

, a hydroxyl (OH) group from each glucose molecule reacts to for a 1, 4 – glycosidic bond. One water molecule is eliminated per linkage.
For a linear structure to result, every second β glucose must be flipped.

62
Q

what is the equation of the polymeristion of cellulose

A

n C6H12O6 –> -(-C6H10O4-O-)- + (n-1) H2O

63
Q

what is biomass

A

 Biomass is a biological material from living or recently living organisms; e.g. animals, plants, manure, cotton, wool.

64
Q

why is cellulose insoluble in water/

A

Cellulose molecules act very much like extended stiff rods.
o This enables them to align side by side into well-organised, water insoluble crystalline lattices (fibres).
o The individual poly chains form very strong IMF. The IMF between cellulose chains is hydrogen bonding.
 As a result of the strong cross linking due to hydrogen bonding, it therefore doesn’t dissolve in water.

65
Q

why is cellulose is a potential raw material for synthetic polymers and other petrochemicals

A

It is a carbon chain structure- abundant source of hydrocarbons needed in petrochemical industries

cellulose can be broken down into β glucose units and fermented into alcohol

66
Q

why is a strong catalyst required to dehydrate ethanol to form ethylene

A

o Although ethanol can be readily dehydrated to form ethylene, a strong catalyst is required as the hydroxyl functional group (-OH) is bonded relatively strongly to the CH3CH2 chain. As such, a catalyst lowers the activation energy required for a chemical reaction to take place by providing an alternate pathway for the reaction to occur.

67
Q

why is a strong catalyst required to dehydrate ethanol to form ethylene

A

o Although ethanol can be readily dehydrated to form ethylene, a strong catalyst is required as the hydroxyl functional group (-OH) is bonded relatively strongly to the CH3CH2 chain. As such, a catalyst lowers the activation energy required for a chemical reaction to take place by providing an alternate pathway for the reaction to occur.

68
Q

why is a weak catalyst required to form ethanol from water and ethylene

A

Just as ethanol may be dehydrated to form ethylene, the addition of water to ethylene will produce ethanol. However, unlike the dehydration process, the presence of the double bonds within ethylene considerably decreases the energy required in order for the reaction to occur. As such, a weaker catalyst such as dilute sulfuric acid may be used.

69
Q

Write the reaction in which glucose is made from sucrose and water

A

C12H22O11(aq) + H2O(l) —–(sucrase)—–> 2C6H12O6

Sucrose + water glucose

70
Q

Write the reaction where ethanol is made from glucose

A

C6H12O6(aq) ——–(zymase)——> 2C2H5OH(aq) + 2CO2(g)

71
Q

Does sucrose have a high or low solubility in water?

A

high
o This means that the mother liquor (molasses) left over after sucrose has been crystallised out still has high sucrose content.
o Therefore, ethanol can be obtained from the waste product

72
Q

outline the steps for the Industrial production of Ethanol from Sugar Cane

A
  1. Suitable crops such as sugar cane are cultivated and glucose is extracted.
  2. A sugary mixture with yeast added is heated at room temperature in anaerobic conditions.
  3. A concentration of 15% ethanol can be reached through this process, after which the yeast will no longer produce ethanol.
  4. The solution may be distilled to obtain higher concentrations of ethanol
73
Q

Why are alcohols of high chain length insoluble in water?

A

as the chain length increases, the non-polar region increases in significance. Hence, solubility decreases.

74
Q

What can ethanol be used for?

A

o Cosmetics (e.g. perfumes and deodorants)- ethanol vapourises away leaving behind Esther.
o Food colourings and flavourings (vanilla essence)
o Medicinal preparations (e.g. antiseptics used to prepare patients for surgery and to clean surgical instruments) – iodine
o Cleaning agents
dissolving medicine for kids or old people

75
Q

Write the equation for the combustion of ethanol

A

C2H5OH(l) + 3O2(g) ————> 2CO2(g) + 3H2O(l)

76
Q

Why can ethanol be called a renewable fuel

A

Ethanol is fermented from glucose, which consists of carbon dioxide and water. As such, sugar cane farming, which has high levels of glucose, is an effective primary source of the components used to produce ethanol. It is for this reason that ethanol is called a renewable fuel.

77
Q

what is ethanol’s molar heat of combustion

A

1360 kJ/mol.

78
Q

Reasons for the use of ethanol to be used as a fuel alternative

(ADV/ DISADV and EValuAtion)

A

Increasing scarcity of economically recoverable oil deposits will lead to higher costs of crude oil and fuel derivatives.

ADV

  • When added to petrol, ethanol is the fuel extender
  • Ethanol blends keep the fuel systems cleaner as it does not leave gummy deposits as it is a good solvent
  • Renewable resource, reductions in greenhouse gas emissions
  • More energy efficient fuel- can undergo complete combustion more easily

DISADV
-Large amounts of energy and land required for the production of
ethanol
-Ethanol blends have a lower Motor Octane Rating than premium fuels (lower performance and has less knock resistance)
-Ethanol has a lower energy density and heat of combustion than octane and diesel, resulting in lower mileage
-Ethanol blends of above 10% require engine modification (therefore costly for consumers)

EVALUATIOn
o Ethanol has great potential to be used as a renewable alternative fuel, however, its use is currently limited due to its cost.

79
Q

What are the Obstacles in the Production of Ethanol

A

The production of glucose through photosynthesis requires many plants

  • This requires a large amount of fertiliser to replace the nutrients taken from the ground, with many fertilisers still being reliant on coal. There is also a large amount of energy required for harvesting of crops.
  • This drawback can be overcome by using existing agricultural waste products in the production of cellulosic ethanol.
    Fermentation of glucose can only produce ethanol at 15% v/v.

To produce purer ethanol, the fermented mixture must be distilled, which requires a lot of energy, also often derived from coal.

  • This drawback can be overcome by using new methods of separation, such as phase separation technology.
80
Q

Describe conditions under which fermentation of sugars is promoted

A

o A glucose-containing solution must be present. If a solid containing glucose is used, water must be added to form a solution.
o Yeast must be present.
o Anaerobic conditions, i.e. no oxygen.
o A temperature roughly at body temperature is best, i.e. 37◦C.

Although a temperature of 37◦C is not necessary for the reaction, which will occur at lower temperatures, a higher temperature will cause the reaction to occur faster. However, the temperature should not be raised above 37◦C, as the yeast cannot survive.

81
Q

Summarise the chemistry of the fermentation process

A

o The yeast included in the reaction secretes an enzyme complex known as zymase which catalyses the process of glucolysis, which refers to the conversion of glucose into ethanol and carbon dioxide. An ethanol percentage of approximately 15% can be successfully produced, at which point the yeast will begin to die due to the concentration of ethanol, and the reaction will halt.
o To obtain higher concentrations of ethanol, distillation or fractional distillation must be used.

POM (2 decks)

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