Topic 10

Question 1

What are the two types of bond fission?

Answer 1

Heterolytic and homolytic

Question 2

What is homolytic bond fission?

Answer 2

• A covalent bond between two atoms breaks and each atom takes an electron
• formation of free radicals

Question 3

What is heterolytic bond fission?

Answer 3

When a covalent bond is broken between two atoms in a molecule with one taking both electrons

Question 4

What is produced in complete combustion reactions?

Answer 4

CO2+H20

Question 5

Why do alkanes make good fuels?

Answer 5

Release large amounts of heat

Question 6

What are the products of incomplete combustion?

Answer 6

C or CO

Question 7

Why are alkenes reactive?

Answer 7

They have a carbon carbon double bond

Question 8

What reaction do alkenes undergo?

Answer 8

Electrophillic addition

Question 9

Hydrogenation

Answer 9

Alkene+ H2= Alkane
Reagant= Ni
Conditions = high temperature and pressure

Question 10

Halogenation ( with halogen)

Answer 10

Alkene+ Haolgen= Dihaloalkane

C2H4+Br2=CH2BrCH2Br

Question 11

Halogenation ( with hydrogen halides)

Answer 11

Alkene+ Hydrogen halide = halogenoalkanes
Reagant= The hydrogen halide
C2H4+HBr= CH3CH2Br OR CH2BrCH3

Question 12

Hydration

Answer 12

Alkene+ H20 = Alcohol
Reagant = H2SO4
Conditions = H20 as steam

Question 13

What do unsymmetrical alkenes have?

Answer 13

More than one end product

Question 14

Oxidation of primary alcohols

Answer 14

-Partial oxidation = aldehyde ( CHO)
Condition = heat under distillation
Reagant= Acidified potassium dichromate
Colour change = Orange - Green

-Further oxidation = carboxylic acid( COOH)
Condition= Heat under reflux
Reagant= Acidified potassium dichromate
Colour change = Orange - Green

Question 15

Oxidation of secondary alcohols

Answer 15

Complete oxidation = ketones ( C-CO-C)
Reagant= Acidified potassium dichromate
Colour change = Orange - Green
Condition = Heat under reflux

Question 16

Oxidation of tertiary alcohols

Answer 16

-NONE

Question 17

What reaction does halogenoalkanes undergo?

Answer 17

• Nucleophilic substitution

- SN1 and SN2

Question 18

What are nucleophiles?

Answer 18

Have lone pairs of electrons to donate and are attracted to regions of positive charge

Question 19

What reaction do alkanes undergo?

Answer 19

Free radical substitution and as they have low reactivity

Question 20

Why are alkanes unreactive?

Answer 20

• carbon to carbon single bond
• the C and H bonds are non polar
• The C-C and C-H bonds are relatively strong

Question 21

Free radical substitution for methane and Cl

Answer 21

-Alkanes + haolgen = Dihaloalkane or halogenoalkane
Initiation
Cl2 -- Cl. + Cl.
Propagation
CH4+Cl. = CH3. + HCl
CH3.+ Cl2 = CH3Cl+ Cl.
Termination
Cl.+Cl.= Cl2
CH3.+CH3. = C2H6
CH3.+ Cl. = CH3Cl

Question 22

What is the test for unsaturation?

Answer 22

• When bromine water is added to an alkene and the water is decolourised because there is a double bond
• When added to an alkane there is no colour change
• Unsaturated = double bond or triple bond
• Saturated = single bond

Question 23

What is PVC?

Answer 23

A polymer made from chloroethene

Question 24

How are additional polymers formed?

Answer 24

When smaller unsaturated molecules react together

Question 25

Draw the additional polymer of chloroethane

Question 26

Combustion of alcohols

Answer 26

- Incomplete combustion = CO+ H20 OR C+H20 - Complete combustion = CO2 + H20 - As the number of carbons increase so does the enthalpy change ( becomes more negative)

Question 27

What two functional groups react together to get an Ester and water?

Answer 27

Carboxylic acid + Alcohol

Question 28

Esters

Answer 28

- Reagant = Concentrated sulfuric acid ( H2SO4) | - Nucleophillic substitution reaction

Question 29

Reaction of ethanoic acid and ethanol

Question 30

Draw the structure of benzene

Question 31

What reaction does Benzene undergo?

Answer 31

Electrophillic substitution

Question 32

What is structural isomerism?

Answer 32

Having the same molecular formula but different arrangement of the atoms

Question 33

What three things increase the BP of organic compounds?

Answer 33

- molar mass, functional group and structure

Question 34

Why do branched isomers have a lower BP then straight chained isomers?

Answer 34

The branches prevent the molecules from getting close together which decreases the strength of the london forces

Question 35

What is the physical evidence for benzene structure?

Answer 35

The length and strength of the carbon to carbon bonds are intermediate between the single and double bond

Question 36

What is the chemical evidence for structure of benzene?

Answer 36

Undegos substiturion reactions and not addition reactions