4-O Alkenes

Question 1

What are alkenes

Answer 1

Unsaturated hydrocarbons

Question 2

What type of bond does an alkene have

Answer 2

Double covalent bond
One is a pi bond (high electron density above and below bond)
One is a sigma bond (high electron density between nuclei)

Question 3

Electrophillic addition of alkenes with Br2 (g) and conditions

Answer 3

Induced dipole force between two bromine molecules allowing one to have a slightly Delta positive charge and one to have a slightly Delta negative charge
S+ Br attracted to electron dense double C=C bond, breaks it and forms C-Br bond
S- Br attracted to +ve carbon forming another C-Br bond

Room temp

Question 4

Electrophilic addition of alkane with HBr and conditions

Answer 4

hydrogen will have a slightly Delta positive charge whilst a halogen will have a slightly Delta negative charge
S+ H atom attracted to electron dense C=C double bond, breaks it forming a C-H bond
S- halogen attracted to +ve carbon atom forming a C-Br bond

Room temp

Question 5

Electrophilic addition of sulphuric acid to alkene and conditions for reaction

Answer 5

Methyl/Ethel/propyl/butyl….. hydrogen sulphate

Conce H2SO4, room temp

Question 6

Formula of H2SO4

Answer 6

OH-OH-S=O=O

Question 7

Electrophilic addition
Hydrolysis of alkyl hydrogensulphate and conditions for reaction (2step alcohol production with electrophilic addition of H2SO4)

Answer 7

Forms alcohol and hydrogen sulfate
Warm mixture

Question 8

Conditions for industrial hydration of alkenes to form alcohols (one step alcohol formation)

Answer 8

High temp, 300°c
High pressure, 65 atm
H3PO4 catalyst

Question 9

What’s an electrophile

Answer 9

An electron pair acceptor

Question 10

Why are 3°>2°>1° carbon cations more stable (unsymmetrical alkenes)

Answer 10

Because a secondary/tertiary carbocation is more stable than a primary carbocation due to a positive inductive effect from alkyl groups

Question 11

How is a major product formed

Answer 11

H attaches to C with most H atoms
Halide or HSO3Ō attach to C atom with most alkyl groups

Question 12

How is a minor product formed

Answer 12

H attaches to C atom with least H attached
Halide or HSO3Ō attaches to C atom with least alkyl groups

Question 13

How to test for alkenes

Answer 13

Bromine water in the presence of a double bond decolourises

Question 14

What are addition polymers made from

Answer 14

Alkenes and substituted alkenes

Question 15

How to draw the repeating unit of a polymer

Answer 15

Take out section until the chain repeats, draw with double bond across two carbons, leave two end bonds empty

Question 16

Why are addition polymers unreactive

Answer 16

Strong non polar C-C and C-H bond

Question 17

Uses and properties of poly(chloroethene)/PVC and how they are influenced by plasticiser

Answer 17

Water proof, electrical insulator, unreactive with acids
As a raw molecule it’s rigid, strong, polar molecule due to a permanent dipole between s+ carbon and s- chlorine adds to the van der waals present, makes window frames
Plasticiser weakens intermolecular forces allowing for flexibility between chains, can insulate electrical wires