HALOALKANES/ALKENES Flashcards
(25 cards)
What is a free radical
Species which has a single unpaired electron
Why do we need UV light in free radical substitution
UV light provides energy needed to break Cl-Cl bond
What does • mean in free radical substitution
• represents single unpaired electrons
What type if process is
Cl2 ——> 2Cl •
Homolytic fission
Define hydrolysis
Splitting mo,ecules using water
Define nucleophile
Donate lone pair if electrons
Define substitution
H atom is replaced by another atom
Define nuckeophilic substitution
Replacement of halogen by nucleophile
What is caused by ozone depletion
Skin cancer
Plant leaf damage
Ozone depletion equations
O2 ———-> 2O •
O2 + O (equalibrium sign) O3
Why do we use CFCs (chlorofluorocarbons) (3 marks)
Non-toxic
Volatile
Inert gases
Explain How chlorine atoms catalyse decomposition if ozone with equations
Initiation
CFCl3 ——-> Cl• + •CFCl2
Propagation
Cl• +O3 ——> ClO• + O2
ClO• + O3 ———-> Cl• + 2O2
Termination
Cl• + Cl• ——> Cl2
Overall reaction
2O3 ——-> 3O2
Strength between Carbon-halogen
Give 2 examples
Stronger bonds are harder to break
C-I weakest bond , less energy required
C-Cl strongest bond , more energy required
What is positive inductive effect
Ability of an alkyl group to release electron density through double bond
Formation of the major products
Major product is formed via more stable carboncation
Due to positive inductive effect
Physical properties of alkenes
No polar bonds
Insoluble in water
Van der walls intermolecular forces
Define addition polymers
Long chain formed from many monomers & no other product formed
Test for alkenes
Bromine water
If alkene present forms colourless solution
Digine unsaturated hydrocarbons
Contains c=c bonds
Difine electrophile
Electron pair acceptor
Define steroisomerims
Same structural formula but different arrangement if atoms in space
How does alkene form E/Z isomers
Due to restriction around c=c bond and 2 different groups attached to each C of the C=C
Bonding in alkenes
Overlap of pi bonds Electrons are electron rich so are suspectible to attack from positive species
Uses of poly(chloroethane)
Water pipes
Aprons
Vinvyl records
