4. solids liquid gas
•Definite shape and
volume
Have definite
volume but no
definite shape
No definite shape
and volume
•Molecules are
closely packed
Molecules are less
closely packed
Far apart
•Force of attraction
is strong
Less stronger than
that in solid state
Very less
•It is difficult to
compress
Compressed more
easily than solids
Easy to compress
5. Pressure
• Force exerted on unit area of a plane
• Number of gas molecules increases ,
the number of collisions also increases and
pressure increases.
• pressure increases volume decreases
6. LIQUIFACTION TEMPERATURE
• The temperature at which the
gaseous molecules come closer and
changes to liquid state is called
liquefaction temperature
7. Critical temperature
• The temperature above which the gas cannot
be liquefied is called critical temperature
GAS CRITICAL TEMPERATURE
•HELIUM
•NITROGEN
•CARBON -DIOXIDE
5.2
126.4
304.2
8. Robert Boyle (1627-1691)
Birth: 1660, Ireland
Published book on Gases: 1680.
Boyles law
• The volume of a fixed mass of gas is inversely proportional
to its pressure at constant temperature.
V α 1/P
V =K×1/P
PV=constant
9. Jacques Alexandria Cesar Charles(1746-1823)
Charles law
At constant pressure the volume
of a fixed mass of a gas is directly
proportional to its temperature in
Kelvin scale
VαT
V=K×T
V/T=constant