5.4 Halogen Derivatives
5.4.1 Halogeno Compounds
LO: I know a variety of uses for
halogeno compounds
NAME
STRUCTURE
trichloromethane
(chloroform)
1,1,1-trichloroethane
USE
H
Cl
anaesthetic
C Cl
Cl
H Cl
solvent
H C C Cl
H Cl
chloroethene
(vinylchloride)
tetrafluoroethene
Cl
H
C C
H
H
F
F
C C
F
F
manufacture
of PVC
manufacture
of Teflon
LO: I know a variety of uses for halogeno compounds
5.4.2 Chlorofluorocarbons
LO: I understand the structure and
properties of CFCs
Chlorofluorocarbons are based on alkane molecules
where the hydrogens have been replaced by a
mixture of chlorine and fluorine.
dichlorodifluoromethane
refrigerant
neutral
insoluble
unreactive
non-flammable
easily liquefied
long lasting
Cl
Cl
C F
F
propellant
LO: I understand the structure and properties of CFCs
CFCs were used as refrigerants instead of ammonia
and sulphur dioxide which are toxic .
CFCs were used as propellants instead of propane
and butane as they were not as dangerous (nonflammable).
The use of CFCs was banned when it was discovered
that they destroy ozone .
LO: I understand the structure and properties of CFCs
5.4.3 Ozone
LO: I understand how CFCs cause a
problem for the ozone layer.
Ozone provides a protective layer around the Earth
against the damaging effects of uv radiation.
UV radiation for the sun is responsible for the formation
of ozone in the upper atmosphere:
O2
O + O2
uv
O
+
O
O3
(ozone)
UV radiation also splits CFCs in the upper atmosphere to
produce chlorine atoms.
Chlorine atoms react with ozone , destroying it.
LO: I understand how CFCs cause a problem for the ozone layer.