Resit Exam Ocr Chemistry Unit 2: Module 1 - Basic Concepts And Hydrocarbons

Front 1

Basic Concepts

What is a hydrocarbon?

Back 1

An organic compound consisting of carbon and hydrogen only

Front 2

Basic Concepts

Why can carbon atoms form so many compounds?

Back 2

- It can form bonds with other carbon atoms to make chains and rings

- Can form single, double or triple bonds to other carbons

- Can bond with atoms of other elements - O,H,N,P,Cl,Br,Fl, I etc

Front 3

Basic Concepts

How many electrons in the outer shell of carbon?

Thus how many bonds can it make?

Back 3

4

Front 4

Basic Concepts

Define saturated hydrocarbon

Back 4

Hydrocarbons with single bonds only

Front 5

Basic Concepts

Define unsaturated hydrocarbon

Back 5

Hydrocarbons with one or more double bonds

Front 6

Basic Concepts

Define aliphatic hydrocarbon

Back 6

A hydrocarbon with carbon atoms joined together in straight or branched chains

Front 7

Basic Concepts

Define alicyclic hydrocarbon

Back 7

A hydrocarbon with carbon atoms arranged in a ring structure

Front 8

Basic Concepts

Define functional group

Back 8

The part of an organic molecule responsible for its chemical reactions

Front 9

Basic Concepts

Define homologous series

Back 9

A series of organic compounds with the same functional group but with each successive member differing by CH2

Front 10

Basic Concepts

Define Alkane

Back 10

The homologous series with the general formula CnH2n+2

Front 11

Basic Concepts

What is nomenclature?

Back 11

A system of naming compounds

Front 12

Basic Concepts

What is an alkyl group?

Back 12

An alkane with a hydrogen atom removed, eg. CH2, C2H5

Front 13

Basic Concepts

Draw 2,3,3-trimethylpentane

Back 13

Front 14

Basic Concepts

Name

Back 14

2,3,-dimethylbut-2-ene

Front 15

Basic Concepts

Draw 2,3,4-trimethylhexane

Back 15

Front 16

Basic Concepts

Name

Back 16

2-chloropropanol

Front 17

Basic Concepts

Name

Back 17

3-bromo, 2-chloro, 2-methylbutane

Front 18

Basic Concepts

What is empirical formula?

Back 18

The simplest whole-number ratio of atoms of each element present in a compound

Front 19

Basic Concepts

A hydrocarbon contains 85.63% C and 14.37% H, Calculate the empirical formula

Back 19

85.63/12 = 7.14

14.37/1 = 14.37

1:2

CH2

Front 20

Basic Concepts

What is molecular formula?

Back 20

The actual number of atoms of each element in a molecule

Front 21

Basic Concepts

A compound has an Empirical formula of CH2O and relative molecular mass of 60.

Find the molecular formula.

Back 21

CH2O = (12+1+1+16) = (30)

60/30 = 2

C2H4O2

Front 22

Basic Concepts

What is general formula?

Back 22

The simplest algebraic formula for a member of its homologous series

Front 23

Basic Concepts

What are the general formulas you need to know?

Back 23

Alkanes - CnH2n+2

Alkenes - CnH2n

Alcohols - CnH2+1OH

Front 24

Basic Concepts

What is displayed formula?

Back 24

The formula that shows the relative positioning of all the atoms in a molecule and the bonds between them

H

H-C-H

H

Front 25

Basic Concepts

What is structural formula?

Back 25

Formula that shows the minimal detail for the arrangement of atoms in a molecule.

CH3CH2CH3

Front 26

Basic Concepts

What is skeletal formula?

Back 26

A simplified organic formula, with hydrogen atoms removed from alkyl chains, leaving just a carbon skeleton with associated functional groups

Front 27

Isomerism

What are structural isomers? give the three ways in which they can occur

Back 27

Structural isomers are molecules with the same molecular formula but different structural arrangement of atoms

1) Differing functional group position

2) Different functional groups entirely (Ex aldehyde/ketone)

3) Branching!

Front 28

Isomerism

What are stereoisomers?

Back 28

Compounds with the same structural formula, but with a different arrangement of the atoms in space

Front 29

Isomerism

What criteria is required for E/Z isomerism ?

Back 29

- C=C bond must be present

- Each carbon must be attached to two different groups

Front 30

Isomerism

Define E/Z isomerism

Back 30

A type of stereoisomerism in which different groups attached to each carbon of a C=C double bond may be arranged differently in space due to restricted rotation of the C=C bond.

Front 31

Isomerism

Define Cis- Trans isomerism

Back 31

A special type of E/Z isomerism in which there is a non-hydrogen group and a hydrogen group on each C of a C=C double bond.

Cis/Z = H atoms on the same side

Trans/E = Atoms on different sides

Front 32

Organic Reagents

In what two ways can bonds be broken ?

Back 32

Heterolytic or Homolytic fission

Front 33

Organic Reagents

Define homolytic fission

Back 33

The breaking of a covalent bond with one of the bonded electrons going to each atom, forming two radicals.

Front 34

Organic Reagents

Define heterolytic fission

Back 34

The breaking of a covalent bond with both of the bonded electrons going to one of the atoms forming a cation and an anion

Front 35

Organic Reagents

What is a radical?

Back 35

A species with an unpaired electron

Front 36

Organic Reagents

Define nucleophile

Back 36

An atom or group of atoms that is attracted to an electron deficient centre or atom where it donates a pair of electrons to form a covalent bond

Front 37

Organic Reagents

Define electrophile

Back 37

An atom or group of atoms that is attracted to an electron rich centre or atom where it accepts a pair of electrons to form a covalent bond.

Front 38

Organic Reagents

Define addition reaction

Back 38

A reaction in which a reactant is added to an unsaturated molecule to make a saturated molecule

2 Reactants ---> 1 Product

Front 39

Organic Reagents

Draw the reaction between Ethene + Br 2

Back 39

Front 40

Organic Reagents

Define substitution reaction

Back 40

A reaction in which an atom or group of atoms is replaced with a different atom or group of atoms

2 Reactants ----> 2 Products

Front 41

Organic Reagents

Draw the reaction between Bromoethane and OH-

Back 41

Front 42

Organic Reagents

What is an elimination reaction?

Back 42

The removal of a molecule from a saturated molecule to make an unsaturated molecule

Front 43

Organic Reagents

Draw the elimination of ethanol. Include the conditions.

Back 43

Front 44

Organic Reagents

What does % yeild measure?

Back 44

The proportion of products formed in a reaction.

Front 45

FUEL N' POOP

What is crude oil?

Back 45

A fossil fuel made from naturally decaying plants and animals - a mixture of different hydrocarbons (mostly unbranched)

Front 46

FUEL N' POOP

Why do we like crude oil?

Back 46

Some of its components are valuable and are used in petrol, kerosene and heating and lubricating oils

Front 47

FUEL N' POOP

What is fractional distillation ?

Back 47

The separation of components in a liquid mixture into fractions which differ in boiling point (and hence chemical composition by means of distillation, typically using a fractionating column

Front 48

FUEL N'POOP

How can you obtain a pure hydrocarbon?

Back 48

1) Separate the complex mixture of hydrocarbons into fractions - each consisting of a mixture of hydrocarbons with similar boiling points

2) Further distillation of a crude oil fraction can be used to obtain a pure hydrocarbon

Front 49

FUEL N' POOP

Describe the process of fractional distillation

Back 49

1) Fractional distillation takes place in a fractionating column

2) First, the crude oil is vaporised by heating

3) It is then passed into the fractionating column

4) The column is hotter at the bottom than at the top and the gases pass up the column through a series of bubble caps

5) Eventually, as they rise, the gases reach a temperature that is lower than their boiling point so the vapour condenses to a liquid

6) The liquid fractions are then tapped off in storage containers

Front 50

FUEL N' POOP

Draw and annotate a fractionating column

Back 50

Front 51

FUEL N' POOP

What can you do with the fractions obtained from crude oil?

Back 51

- Used as fuels

- Can be further processed to make petrochemicals (chemicals from natural gas and oil)

- Can be distilled further to form pure liquids in other fractionating columns, operating over a narrower range of temperatures

- Bitumen can be used in road surfacing or roof coverings

Front 52

FUEL N' POOP

Describe the bonding between alkane molecules

Back 52

Weak intermolecular forces of attraction between molecules -> Van Der Waals.

Front 53

FUEL N' POOP

Describe the effect of chain length on the boiling points of alkanes

Back 53

As the chain length increases, boiling point increases.

This is because the intermolecular forces between the molecules get stronger. A longer chained alkane has more points of contact between the molecules = more VDW forces between the molecules.

It takes more energy and thus a higher temperature to separate the molecules

Front 54

FUEL N'POOP

Describe the effect of branching on the boiling points of alkanes.

Back 54

Branched isomers have lower boiling points because there are fewer points of contact = fewer VDWs.

Also, branched molecules cannot get as close to eachother as unbranched ones, thus decreasing intermolecular forces. Therefore, less energy is required to separate the molecule.

Front 55

FUEL N' POOP

Write the equation for the combustion of methane

Back 55

Front 56

FUEL N' POOP

What is the function of propane and butane?

Back 56

They are easily liquefied and are commonly known as liquefied petroleum gas or LPG. They are used as fuels in barbecues, patio heaters, and portable cooking appliances such as those used in camping.

Front 57

FUEL N' POOP

Write the equation for the complete combustion of Octane.

Back 57

Front 58

FUEL N' POOP

Why will octane undergo incomplete combustion?

Back 58

Most cars have a limited supply of oxygen

Front 59

FUEL N' POOP

Write the equation for the incomplete combustion of octane

Back 59

Front 60

FUEL N' POOP

Describe the properties of CO, how it is formed, its effects and why it is produced

Back 60

- Colourless, odourless gas - poisonous

- at home, it can be formed from faulty domestic heating systems, blocked fuels/chimneys or inadequate ventilation

- prevents haemoglobin in red blood cells from binding with oxygen and the body's tissues become starved of oxygen

- CO is produced when any fossil fuel is burned with an insufficient supply of Oxygen

Front 61

FUEL N' POOP

What is cracking?

Back 61

The breaking down of long-chained saturated hydrocarbons to form a mixture of shorter-chained alkanes and alkenes.

Front 62

FUEL N' POOP

Why would you need to make short chained alkenes from longer chained ones?

Back 62

After the fractional distillation of crude oil there is a surplus of long-chained hydrocarbons. You want short-chained hydrocarbons for use of fuels and for polymer production

Front 63

FUEL N' POOP

What are the conditions for Cracking?

Back 63

Zeolite catalyst

450 degrees

Front 64

FUEL N' POOP

Define catalyst

Back 64

A substance that increases the rate of a chemical reaction without being used up

Front 65

FUEL N' POOP

Draw one possible cracking reaction of dodecane, C12H26

Back 65

Front 66

FUEL N' POOP

How can you produce branched alkanes from unbranched alkanes?

Back 66

ISOMERISATION

Front 67

FUEL N' POOP

Draw the isomerisation of pentane

Back 67

Front 68

FUEL N' POOP

How can you produce alicyclic/aromatic hydrocarbons from aliphatic hydrocarbons

Back 68

REFORMING

Front 69

FUEL N' POOP

Draw the reforming process for pentane

Back 69

Front 70

FUEL N' POOP

Draw the reforming process for heptane

Back 70

Front 71

FUEL N' POOP

What does an octane rating close to 100 indicate?

Back 71

That the fuel burns efficiently

Front 72

FUEL N' POOP

Why are branched alkanes used in fuels for car engines?

Back 72

Branched and cyclic alkanes promote more efficient combustion than straight chained alkanes

Front 73

FUEL N' POOP

What is the hydrogen produced during reforming used for?

Back 73

Other chemical processes such as ammonia production and margarine production

Front 74

FUEL N' POOP

How have we come to rely on the chemicals produced by crude oil?

Back 74

Over 90% of crude oil produced is used as a fuel source .

Petrochemicals (plastics, pharmaceuticals, cosmetics, dyes and inks) are made indirectly from crude oil

Front 75

FUEL N' POOP

What does a good fuel need?

Back 75

- to be readily available

- to be easily transported

- to be inexpensive

Front 76

FUEL N' POOP

What are the disadvantages of burning hydrocarbons?

Back 76

It produced pollutants:

- CO - a toxic gas formed by incomplete combustion in the internal combustion engine

- CO2 - Contributes to global warming via the greenhouse effect

- Nitrogen Oxides - Contributes to acid rain and destruction of forests

- Sulfur Dioxide - Contributes to acid rain

Front 77

FUEL N' POOP

Explain Global warming

Back 77

Burning fuels to generate energy releases CO2 and other greenhouse gases into the atmosphere. These greenhouse gases prevent heat from escaping the atmosphere, and hence lead to increased temperatures on Earth

Front 78

FUEL N' POOP

What is the effect of increased temperatures on Earth?

Back 78

A change in climate - heavier rain, more frequent, violent storms, polar ice caps could melt, sea levels rise, flooding etc

Front 79

FUEL N' POOP

What is a biofuel?

Back 79

A fuel that is derived from living material such as plants, or from animal waste

Front 80

FUEL N' POOP

Give two examples of crops specifically grown for energy use

Back 80

Sugar cane

Oilseed Rape

Front 81

POOP

How is ethanol utilised + made?

Back 81

Ethanol can be made by fermenting sugar and other carbohydrates.

It burns efficiently in plentiful supply of oxygen to give CO2 and H2O.

Ethanol can be blended with petroleum causing fuel to burn more efficiently. This also reduces harmful exhaust emissions.

Front 82

FUEL N' POOP

What is bioethanol?

Back 82

A fuel oil derived from natural sources such as plants - the most popular source of biodeisel is Rapeseed.

It is normally blended with normal diesel.

Front 83

ALKANES AND SUBSTITUTION REACTIONS

What are the conditions for the halogenation of alkanes?

Back 83

Alkanes react with halogens in the presence of UV LIGHT or a temp of 300 degrees

Front 84

ALKANES AND SUBSTITUTION REACTIONS

Write the reaction between methane and chlorine

Back 84

CH4 + Cl2 ---> CH3Cl +HCl

Front 85

ALKANES AND SUBSTITUTION REACTIONS

What kind of reaction is this?

Define this reaction :3

Back 85

It is a RADICAL SUBSTITUTION REACTION - a type of substitution reaction in which a radical replaces a different atom or group of atoms.

Front 86

ALKANES AND SUBSTITUTION REACTIONS

Explain what occurs in radical substitution

Back 86

- Covalent bonds are broken by homolytic fission to form radicals with an unpaired electron

- A hydrogen atom in the alkane is substituted by a halogen atom

Front 87

ALKANES AND SUBSTITUTION REACTIONS

What is a reaction mechanism?

Back 87

A sequence of steps showing the path taken by electrons in a reaction

Front 88

ALKANES AND SUBSTITUTION REACTIONS

What are the three stages of the chlorination of alkanes?

Back 88

Initiation

Propagation

Termination

Front 89

ALKANES AND SUBSTITUTION REACTIONS

Outline the full mechanism of chlorination of alkanes

Back 89

Step 1: Initiation

Cl-Cl ---> Cl • + Cl •

The Cl-Cl bond in a chlorine molecule is broken by homolytic fission, forming two chlorine radicals.

UV Radiation provides energy for this fission

Step 2: Propagation

1) CH4 + Cl • ----> • CH3 + HCl

2) • CH3 + Cl2 -----> CH3Cl + Cl •

1) Chlorine radicals attack methane : a single C-H bond is broken by homolytic fission, forming a methyl radical, • CH3. HCl is also formed.

2) The • CH3 radical reacts with Cl2 forming CH3Cl and another chlorine radical. This can then be used for the first propagation step.

Step 3: Termination

Two radicals combine to form a molecule

- • Cl + • Cl ---> Cl2

- • Cl + • CH3 ---> CH3Cl

- • CH3 + • CH3 ---> C2H6

The termination stage removes radicals, stopping the reaction,.

Front 90

ALKANES AND SUBSTITUTION REACTIONS

Describe the speed at which propagation occurs and what type of reaction it is

Back 90

Propagation reactions are rapid: the reactions continue until no reactants remain.

It is a CHAIN reaction: Although a Cl • is used in the first step, another is generated in the second step.

This can now react with another CH4 molecule. This continues until the Cl2 is used up or the termination stage removes all the radicals.

Front 91

ALKANES AND SUBSTITUTION REACTIONS

What further reactions can occur?

Back 91

Chloromethane may react with further Chlorine radicals until all Hydrogens have been replaced. This results in a mixture of

CH3Cl

CH2Cl2

CHCl3

CCl4

Front 92

Alkenes

What are alkenes?

Back 92

Unsaturated hydrocarbons with at least one C=C double bond

Front 93

Alkenes

What is the general formula for an aliphatic alkene?

Back 93

CnH2n

Front 94

Alkenes

What reactions do they typically take part in?

Back 94

Addition

Front 95

Alkenes

How is ethene obtained?

Back 95

From the catalytic breakdown of crude oil fractions

Front 96

Alkenes

What are alkenes used to make?

Back 96

Polymers for the plastic industry

Front 97

Alkenes

Explain and draw the formation of a Pi bond.

Back 97

A sigma bond is formed directly between two carbon atoms between two carbon atoms by the overlap of orbitals. Each carbon atom contributes one electron to the electron pair in the sigma bond.

A pi bond is formed above and below the plane of carbon atoms by sideways overlap of p orbitals. Each carbon atoms contributes one electron from a p orbital to the electron pair in the pi bond.

Front 98

Alkenes

Explain how fixed rotation occurs

Back 98

The pi bond fixes the carbon atoms in position, at either end of the double bond

Front 99

Alkenes

In alkanes, each carbon involved in the double bond....

Back 99

Uses 3 e-s in the formation of 3 sigma bonds

Uses 1 e- in the formation of 1 pi bond.

Front 100

Alkenes

Explain the shape of an alkane molecule

Back 100

3 regions of electron density surround each carbon atom in the double bond

Parts of electrons repel eachother as far apart as possible to minimise repulsions

This gives a trigonal planar shape, with 120 degree bond angles

Ethene is a FLAT PLANAR MOLECULE - all atoms are in the same plane

Front 101

Alkenes

Define pi bond

Back 101

The reactive part of a double bond formed above and bellow the plane of the bonded atoms by sideways overlap of p orbitals

Front 102

Alkenes

Describe cyclic alkenes

Back 102

-Cyclic alkenes have a closed ring o carbon atoms containing one or more double bonds

-Most common is cyclohexene

-They do not have the same general formula as aliphatic alkenes

Front 103

Alkenes (reactions)

Why are alkenes more reactive than alkanes?

Back 103

Because of the C=C double bond

Front 104

Alkenes (reactions)

Which is stronger? A C-C or C=C bond?

Back 104

C=C is stronger.

Front 105

Alkenes (reactions)

What does the following information tell you?

Average bond enthalpy

C-C +347 kJmol-1

C=C +612 kJmol-1

Back 105

A double bond is stronger than a single bond but a pi bond is weaker than a sigma bond (612-347 = 265)

Front 106

Alkenes (reactions)

Describe and draw the typical addition reactions of alkenes

Back 106

Front 107

Alkenes (reactions)

Draw and explain the addition of hydrogen to ethene (with conditions pls) (hydrogenation/reduction)

Back 107

Nickel catalyst

150°

Front 108

Alkenes (reactions)

Draw and explain the addition of a halogen to ethene

Back 108

Alkenes react rapidly with halogens such as chlorine, bromine and iodine at room temperature

Front 109

Alkenes (reactions)

Draw and explain the bromination of alkenes

Back 109

When bromine is added to a sample containing an alkene, the colour changes from orange to colourless.

This is used as a test for unsaturation.

Front 110

Alkenes (reactions)

Draw and explain the addition of hydrogen halides to an alkene

Back 110

Hydrogen halides include HCl, HBr and HI. They are gases at room temperature and are bubbled into liquid alkanes.

Front 111

Alkenes (reactions)

Draw and explain the addition of steam to alkenes

Back 111

h3PO4

Steam and the gaseous alkene are heated to a high temperature and pressure in the presence of a phosphoric acid catalyst.

This is called HYDRATION of an alkene and is a method of preparing alcohols used widely in industry.

Front 112

Alkenes (reactions)

Explain what happens when unsymmetric alkenes undergo addition reactions (use propene + HBr as an example)

Back 112

A mixture of organic products is formed.

Front 113

Alkenes (reactions)

Draw and explain the mechanism for the addition of Br2 to ethene

Back 113

1) When bromine approaches an alkene, the electrons in the pi bond repel the electrons in the Br-Br bond, inducing a dipole: Br∂+ - Br∂-

It is now slightly polar.

2) The electron pair in the pi bond is attracted to the partially +ve Br which causes the double bond to break

3) A new bond forms between one C and the Br

4) The Br-Br bond breaks by heterolytic fission - one bromine gets the electron pair

5) A Br- ion and carbocation is formed

6) The +vely charged carbocation is unstable and quickly reacts with the bromide ion to form the final organic product

Front 114

Alkenes (reactions)

What are Terpenes?

Back 114

Alkenes built from whole numbers of Isoprene (C5H8) molecules. The Isoprene molecules can either linked together headd to tail forming chains or can be formed into rings.

Front 115

Alkenes (reactions)

Draw and explain the reaction of C10H16 (Myrcene) with excess hydrogen

Back 115

Nickel catalyst

Front 116

Alkenes (reactions)

Draw a full flowchart, with conditions, for alkenes.

Back 116

Front 117

ALKENES AND INDUSTRY

How are unsaturated compounds used in industry?

Back 117

They are important starting materials for many common industrial processes - i.e. ethene is polymerised to make plastics

Front 118

ALKENES AND INDUSTRY

What are the 3 things ethene is used to make?

Back 118

- 1,2-dichloroethene ClCH2CH2Cl ---> DEGREASER AND PAINT REMOVER

-Ethane-1,2- diol HOCH2CH2OH ---> WIDELY USED AS AN ANTIFREEZE AND IS A KEY MATERIAL FOR MAKING POLYESTERS SUCH AS TERYLENE FOR CLOTHING

-Ethanoic acid CH3COOH ----> VINEGAR + USED IN ORGANIC SYNTHESIS

Front 119

ALKENES AND INDUSTRY

Describe how margarine is made

Back 119

From animal/vegetale fats, mixed with skimmed milk and salt

Front 120

ALKENES AND INDUSTRY

What is the difference between margarines with a high content of mono- or poly-unsaturated fats and butter and other margarines?

Back 120

They are said to be healthier and are often made from sunflower or olive oil

Front 121

ALKENES AND INDUSTRY

What are vegetable oils?

Back 121

Liquids containing long hydrocarbon chains, often with many double bonds - they are polyunsaturated

Front 122

ALKENES AND INDUSTRY

Why must it be hardened?

Back 122

So that is can be spread on bread without soaking into it

Front 123

ALKENES AND INDUSTRY

Describe the process that hardens oils

Back 123

HYDROGENATION

- Hydrogenation adds hydrogen molecules across double bonds in an addition reaction

- It alters the individual molecule in such a way that the oil partially solidifies and hardens

- By adding H2 molecules across different numbers of the many double bonds, we can make margarines with different amounts of hardness - thus affecting the spreadibility

- Partial hydrogenation of unsaturated fats can transform some CIS double into into TRANS - which are now thought to be bad for health

Front 124

POLYMERS

What are polymers?

Back 124

Long-chain molecules built upon monomer units

Front 125

POLYMERS

What is a monomer?

Back 125

A small molecule that combines with many other monomers to form a polymer

Front 126

POLYMERS

What is addition polymerisation?

Back 126

The process in which unsaturated alkene molecules (monomers) add on to a growing polymer chain one at a time to form a long saturated molecular chain

Front 127

POLYMERS

How many different types of monomer is used to make an addition polymer?

Back 127

One.

Front 128

POLYMERS

Define addition polymer

Back 128

A long molecular chain formed by repeated addition reactions of many unsaturated alkene molecules (monomers)

Front 129

POLYMERS

Draw the addition polymerisation of ethene

Back 129

Front 130

POLYMERS

What are the two industrial processes that involved addition polymerisation?

Back 130

- Radical polymerisation

- Ziegler-Natta process

Front 131

POLYMERS

Describe radical polymerisation

Back 131

- Requires 200 degrees and a high pressure

- Reaction leads to branching of the polymer chain and the production of polymer mixtures

- Poly(phenylethene), poly(styrene) and branched poly(ethene) is produced in this way

Front 132

POLYMERS

Describe the Ziegler-Natta process

Back 132

- Requires TiCl3 + Al(C2H5)2Cl catalysts at 60 degrees

- Alkene is passed over the catalyst - conversion is low and any unreacted alkene is recycled and passed over the catalyst repeatedly

-Most common method for the manufacture of non-branched poly(ethene)

Front 133

POLYMERS

What is the general equation for addition polymerisation?

Back 133

Front 134

POLYMERS

What is a repeat unit?

Back 134

A specific arrangement of atoms that occurs in the structure over and over again.

Front 135

POLYMERS

Draw the general formation of poly(ethene)/polythene

Back 135

Front 136

POLYMERS

Draw the general formation of poly(propene)/polypropylene

Back 136

Front 137

POLYMERS

Draw the general formation of polystyrene (poly(phenylethene))

Back 137

Front 138

138

POLYMERS

Draw the general formation of PVC (poly(chloroethene))

Back 138

Front 139

POLYMERS

Draw the general formation of Teflon/PTFE/Poly(tetrafluroethene)

Back 139

Front 140

POLYMERS

What is Orlon?

Back 140

A polymer used as a synthetic fibre. It is resistant to sunlight and atmospheric gases, making it suitable for outdoor use as a tent materials and sunshades.

Repeat unit = H H

C C

H CN

Front 141

POLYMERS AND GREEN CHEMISTRY POOOP

What are the uses of polystyrene/ poly(phenylethene)?

Back 141

- Plastic used in foam packaging

- Insulation

- Food retail

- Model making

Front 142

POLYMERS AND GREEN CHEMISTRY POOOP

What are the uses of poly(ethene)/polyethene?

Back 142

-Most widely used plastic

- Grocery bags, shampoo bottles, toys etc

Front 143

=POLYMERS AND GREEN CHEMISTRY POOOP

What are the uses of poly(propene)/polyproylene?

Back 143

-Food packaging

-Containtors that are dishwasher safe

- Fibre in carpets

- Used in making synthetic ropes

- Used as a material for certain lab equipment as it is resistant to chemical attack

Front 144

POLYMERS AND GREEN CHEMISTRY POOOP

What physical properties make polymers good for a broad range of uses

Back 144

- They do not react with the substance inside them

- Fairly durable

- Do not break down easily

Front 145

POLYMERS AND GREEN CHEMISTRY POOOP

What is a disadvantage to these properties?

Back 145

It makes them hard to dispose of

Front 146

POLYMERS AND GREEN CHEMISTRY POOOP

What is environmentally bad about plastics?

Back 146

Much of the plastic waste we create includes additives such as colourants, stabilisers and pasticisers which often contain poisonous heavy metal ions.

They are non-biodegradable

Front 147

POLYMERS AND GREEN CHEMISTRY POOOP

What are the two stages to recycling?

Back 147

Sorting- polymer indentification codes are used

Reclamation - Once sorted, polymers are processed. The polymers are manually chopped into small flakes and washed to remove impurities.

This is now sent to manufacturing companies where the pellets are melted and remoulded/

Front 148

POLYMERS AND GREEN CHEMISTRY POOOP

What happens to

a) PET bottles

b) HDDE

c) LDPE

d) LDPE

Back 148

a) Converted to carpets, clothing and new bottles

b) Reused to make hard plastic materials - boxes, bins, water butts

c) Used to make plastic refuse sacks

Front 149

POLYMERS AND GREEN CHEMISTRY POOOP

Describe how polymers can be used as a fuel source

Back 149

Burning polymers under controlled conditions produces heat energy which can be harnessed to make electricity.

Front 150

POLYMERS AND GREEN CHEMISTRY POOOP

Describe what feedstock recycling is

Back 150

Polymers are converted into synthesis gas - a mixture of H2 + CO

Hydrocarbons and synthesis gas is used as a chemical feedstock for concersion into useful products or as a fuel at oil refineries.

Front 151

POLYMERS AND GREEN CHEMISTRY POOOP

Why is recycling poly(vinyl chloride) PVC problematic?

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It has a high chlorine content.

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WWhat is done instead of recycline PVC?

What are the disadvantages?

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It is incinerated - it prevents PVC going into landfill sites - but the combustion of PVC produces toxic fumes and may cause corrosion to the PVC plant.

Acidic HCl fumes are released.

Hence, PVC incinerators are equipped with pollution control apparatus to minimikse thr elease of these harmful emissions

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POLYMERS AND GREEN CHEMISTRY POOOP

Describe the development of the first commercial PVC recycling plant

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- PVC is seperated from other scrap by dissolving in solvents

- High quality PVC is then recovered by precipitaion from the solvent

- The solvent is recovered and then used again

-This process recycles the PVC coatings of electrical wiring and other PVC waste

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What are bioplastics?

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They are biodegradable or compostable plastics derived from renewable raw materials such as starch, cellulose, maize and lactic acid.

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POLYMERS AND GREEN CHEMISTRY POOOP

How are bioplastics manufactured?

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By non-hazardous processes

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POLYMERS AND GREEN CHEMISTRY POOOP

What happens when bioplastics are disposed of?

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They degrade naturally into the environment to CO2 + H2O

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POLYMERS AND GREEN CHEMISTRY POOOP

How will a biodegradable plastic break down?

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As a result of bacterial activity

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POLYMERS AND GREEN CHEMISTRY POOOP

What is the criteria for compostable plastics?

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They must break down by a biological process during composting to CO2, H2O, inorganic compounds and biomass

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POLYMERS AND GREEN CHEMISTRY POOOP

What is currently being used to replace non-degradable plastics?

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- BIOPLASTICS + CORNSTARCH CUTLERY - used to replace oil-derived poly(ethene). Supermarket bags are made out of plant starch and are also used as bin liners that can be compotsted with the waste inside it.

- COMPOSTABLE DISPOSABLE TABLEWARE from sugar cane fibre is use to replace polystyrene - although they are less resistant to breakdown, they can withstand temperatures up to 100 degrees.

- Poly(lactic) acid is used for cold drink cups - biodegradable in 180 days.