2.5

Question 1

What is a fossil fuel

Answer 1

Fossil fuel is one that is
derived from organisms that
lived long ago.

Question 2

Advantages of fossil fuels

Answer 2

• variety available - each use can be matched to appropriate fuel
• available at all times
• widely available

Question 3

Disadvantages of fossil fuels

Answer 3

• non-renewable
• produces CO2 on combustion - greenhouse gas
• combustion of fossil fuels that contain sulfur and nitrogen leads to acid rain
• carbon monoxide is formed during incomplete combustion

Question 4

What is a non-renewable source

Answer 4

Cannot be reformed in a reasonable timescale

Question 5

What is acid rain and its environmental effect

Answer 5

Rain with lower than expected pH
Combustion of fossil fuels that contain sulfur and nitrogen produce the dioxides which react with water to form sulfuric acid and nitric acid
Contains sulfuric acid and nitric acid
Damages buildings, vegetation and aquatic life
Health issues for people with breathing difficulties

Question 6

Why are alkanes generally unreactive

Answer 6

Non-polar and dont contain multiple bonds

Question 7

What is combustion

Answer 7

When alkanes burn and react with oxygen in exothermic reactions and are used as fuels

Question 8

Complete combustion

Answer 8

Combustion that occurs with excess oxygen
Sufficient oxygen is present
Carbon dioxide and water are produced

Question 9

Incomplete combustion

Answer 9

Combustion that occurs with insufficient oxygen
Carbon monoxide and water is formed
Less energy than complete combustion

Question 10

Why is carbon monoxide toxic

Answer 10

Can inhibit transport of oxygen through the body as it combines with haemoglobin

Question 11

What is halogenation

Answer 11

Reaction between organic compound and any halogen

Question 12

What are the two important reactions of alkanes

Answer 12

Combustion and halogenation

Question 13

What are the 3 mechanisms of halogenation

Answer 13

Initiation
Propagation
Termination

Question 14

What is initiation in halogenation

Answer 14

Reaction that starts the process
Homolytic bond fission of chlorine to produce 2Cl•
Energy needed to break the bond is provided bu uv light

Question 15

What is propagation in halogenation

Answer 15

Reaction by which the process continues/grows
Radicals take part as they’re so reactive
Starts with a radical then produces one so that the chain reaction occurs

Question 16

Cl• + CH4 —>

Answer 16

CH3• + HCl

Question 17

CH3• + Cl2 —>

Answer 17

CH3Cl + Cl•

Question 18

What is termination in halogenation

Answer 18

The reaction that ends the process
Chain reaction continues until 2 radicals meet
CH3•+Cl• —> CH3Cl

Question 19

Overall equation of halogenation

Answer 19

C2H6 +Cl2 —> C2H5Cl + HCl

Question 20

What is a pi bond

Answer 20

One formed by the sideways overlap of p electrons
Double bond
High electron density above and below the plane of the molecule

Question 21

What makes alkenes susceptible to attach by an electrophile

Answer 21

The pair of electrons in the pi orbital

Question 22

What kind of bond fission is involved in electrophilic addition

Answer 22

Heterolytic

Question 23

What is an addition reaction

Answer 23

Reaction in which reagents combine to give one product

Question 24

What is shown by the curly arrows of this electrophilic addition

Answer 24

Movement of the electron pair

Question 25

If the attacking species is non-polar during electrophilic addition, how is a dipole induced

Answer 25

By the negative charge of the pi bond

Question 26

Test for alkenes

Answer 26

Reaction with bromine • brown colour of bromine changes to colourless • use of aqueous bromine as it is safer Reaction with potassium manganate (VII) Reaction with acidified potassium manganate • purple manganate(VII) is decolorised

Question 27

Why, on the addition of HBr to alkenes , 2-bromopropane is the major product and not 1-bromopropane

Answer 27

It has greater stability of the 2• carbonation compared with the 1• carbonation

Question 28

Which type of carbocation

Answer 28

2•

Question 29

Which type of carbocation

Answer 29

1•

Question 30

What is polymerisation

Answer 30

Joining of a very large number of monomer molecules to make a large polymer molecule

Question 31

What is a monomer

Answer 31

Small molecule that can be made into a polymer

Question 32

What is a polymer

Answer 32

Large molecules made by joining many monomers

Question 33

What kind of molecules undergo addition polymerisation and why

Answer 33

Alkenes and substituted alkenes | They have a double bond which is used to join the monomers and nothing is eliminated

Question 34

Think of the polymer that would come of this monomer

Answer 34

Question 35

What is the name of the polymer of ethene

Answer 35

Poly(ethene)

Question 36

Properties of poly(ethene)

Answer 36

Unreactive and flexible | Can be used to make plastic bags

Question 37

Why do polymers have a huge variety of uses

Answer 37

The properties of polymers can be altered by using substituted alkenes as the monomer

Question 38

Properties of poly(propene)

Answer 38

Rigid | Used in food containers and kitchen equipment

Question 39

Properties of poly(chloroethene) or PVC

Answer 39

Flexible | Water pipes, waterproof clothes and insulating covering for electrical cables

Question 40

Properties of poly(phenylethene) or polystyrene

Answer 40

Hard - gives strength and rigidity | Made into an insulator by making holes in the structure

Question 41

Which polymer

Answer 41

Poly(propene)

Question 42

Which polymer

Answer 42

Poly(chloroethene)

Question 43

Which polymer

Answer 43

Poly(phenylethene)

Question 44

Why is CO2 bad for the environment

Answer 44

Absorbs infrared radiation from earth, then it emits it in all directions Some of the radiation goes back towards the earth's surface Causes the surface's temperature to rise Can lead to rising sea levels and changes to crop stability

Question 45

Why are radical reactions hard to control

Answer 45

Further substitution can occur A mixture of products may be formed Unsatisfactory method of getting a high yield of a specific halogenoalkane Can be largely avoided by limiting the amount if the halogen

Question 46

Name of this reaction

Answer 46

Electrophilic addition

Question 47

Monomer or repeating unit

Answer 47

Monomer

Question 48

Monomer or repeating unit

Answer 48

Repeating unit