There are five states of matter: solid, liquid, gas, plasma, and Bose-Einstein condensate (BEC). Plasma is common among stars but not on Earth, while BEC only forms at extremely low temperatures near absolute zero when atoms lose kinetic energy and clump together. Gases are characterized by diffusion, the movement from high to low concentration, and effusion, movement through a small pore. Several gas laws describe gas behavior, including Boyle's law relating pressure and volume, Charles' law relating volume and temperature, Avogadro's law of equal volumes containing equal molecules, and Dalton's law of partial pressures. Real gases deviate from the ideal gas model due to intermolecular forces

1. GASEOUS STATE

2. TYPES
Basically we observe with 3 states of matter namely
 SOLIDS
 LIQUIDS &
 GASES

3. LET’S See …

4. Apart from the 3 states of matter, there are 2 more states
of matter
 Plasma
 Bohr-Einstein Condensate
Plasma is not a common state of matter on the earth ,
but a common one among stars which produces that
excessive heat & light.That means plasma matter has
high kinetic energies.

5. In contrast to this , Bohr-Einstein condensate(BEC) has
very low & even zero kinetic energies.
Due to this zero kinetic energies atoms loose their
molecular motions & begin to clump together and form
condensates named BEC’s.
We have to make a note that kinetic energies are directly
proportional to absolute temperatures & hence BEC’s
also would form & exist at extremely low temperatures.

6. GASES
 As we all know the properties of gases or the gas
mixtures ..
The formost property is DIFFUSION of GASES
 Diffusion is the movement of gases from a region of
higher concentration to a region of lower
concentration which is exactly opposite to OSMOSIS
which is a property of liquids.
 Now this diffusion of gases is measured in terms of
rates of diffusion.

7. Rate of Diffusion(r)
 The volume of a gas that diffuses in unit time is said to
be rate of diffusion (r) of a gas .
r=V/t
or r1/r2 = V1/V2 * t2/t1
if the two gases have equal volumes then ,
r1/r2 = t2/t1

8. EFFUSION
 Similar to diffusion , EFFUSION is also a property of
gases
 Effusion is defined as the movement of gases from a
region of higher concentration to that of lower
concentration through a small pore.
 The best example of effusion are like…
1) Escape of air from balloon
2) Escape of air from punctured cycle tube.
3) Gas leakages from pipes / cylinders

9. GAS LAWS
 A very imp. arena of this chapter is on gas laws.
 Here we shall deal with 5 gas laws….
1) Boyle ‘s law
2) Charles law
3) Avogadros law
4) Grahams law of Diffusion
5) Dalton’s law
Lets see one by one in detail……

10. PV = K
Boyle’s law
 The pressure of a given mass of gas is inversly
proportional to volume at constant temperature.
or

11.  A graph drawn for Boyles law is shown as
Pressure vs Volume
P
V

12.  If a graph of boyles law is drawn between P vs 1/V ,
That is represented as
P
1/V

13.  Similarly if a graph is drawn among PV vs P is given as
PV
P

14. Charles laws
 Statement 1
Charles law -1
1 states that , at constant pressure for every one degree
rise in temperature , the volume of a given mass of gas
changes by 1/273 of its volume at ‘0’ degrees
centigrade.
Vt= V0 1+ t/273

15. Charles law-1 graph
 A graph plotted for statement 1 of charles law is shown
as
V m
v0
0 T

16. Statement - 2
 It states that at constant volume , pressure of a given
mass of gas is directly proportional to temperature
or
At constant pressure, volume of a given mass of gas is
directly proportional to temperature .
V T or P T
V=KT P=KT
V1/V2=T1/T2 P1/P2=T1/T2

17. Graphical representation
 The graphs drawn for charles law 1 & 2 are given as
V3 P3
V2 P2
P1
V1
V P
T T

18. AVOGADRO’S law
 Equal volumes of all gases contain equal number of
molecules under similar conditions of temperature
and pressure.
&
or
or
V n
V=nK V/n = K
V1/n1=V2/n2
V1n2=V2n1

19. IDEAL GAS EQUATION
From the 3 gas laws , studied till now … ideal gas
equation can be derived as follows
PV=K ……… eq 1
P=KT ……... eq 2
V= nK ………. eq 3
From 1,2 & 3 PV=nKT
Replacing constant K, with Universal gas Constant we
get
PV=nRT

20. Values of ‘R’
NUMERICAL VALUE UNITS
8.314 Joules
0.08206 L.atm
1.987 Calories
62.36 L.torr
82.1 atm.cc

21. GRAHAMS LAW OF DIFFUSION
 Grahams law of diffusion states that the rate of
diffusion of a gas is inversly proportional to the
squareroot of density or molecular weight.

22. DALTONS LAW
 It states that , at constant temperature the total
pressure of a gas in a gaseous mixture is the sum of
partial pressures of the gases.
P= p1+p2+p3+……..
At const. ‘T’ ; the partial pressure of a gas is directly
proportional to its molefraction (

23. Kinetic gas Equation
 The kinetic gas equation is given as
PV=1/3 mnc2

24. Types of velocities
 Gas molecules exhibit with three different kinds of
velocities …
1) Average velocity ( C )
2) Most probable velocity ( C p )
3) Root meansquare velocity ( C rms )

25. Ratio of velocities
The ratio of C p , C & Crms can be given as
1:1.128 : 1.223

26. INTERMOLECULAR FORCES vs
THERMAL ENERGY
 Inter molecular forces are forces which mediate
interraction between molecules; be it forces of
attraction or forces of repulsion.
 These intermolecular forces of attraction are cheifly
studied as hydrogen bonding , dipole forces of
attraction.
 Thermal energy is the average kinetic energy of the
molecules of a substance.
Thermal energy is a very key factor for the liquifaction
of gases.

27.  Physical state of a substance always depends on the
extent of intermolecular forces & thermal energy.

28. REAL GAS vs IDEAL GAS
 Gases which follow ideal gas equation i.e PV=nRT
are said to be ideal gases
&
Gases which donot follow ideal gas equation are said be
real gases.
And in general , all gases are real & no gas is ideal.
The reason behind real behaviour of gases are
1) Molecules of a gas donot exhibit any forces of
attraction among them.
2) Volume of gas occupied is negligibly small wrt space
occupied by the gas.

29. GRAPHICAL NOTE
CO
CH4
H2 He
PV P Real gas
ideal gas
Ideal gas
P V

30. LIQUIFACTION OF GASES
 Ideal gases cannot be liquified.it is only a real gas that
can be liquified.
 Gases can be liquified on cooling below their boiling
points.But if the gas to be liquified is having a very low
boiling point , then it cannot be liquified by cooling
furthur.
Hence an another technique called JOULE-THOMPSON
EFFECT is to be used.
Principle behind this technique is cooling of gases by
expansion from high pressure to low pressure.

31.  There are 2 key points to achieve liquifaction of gases
1) Critical temperature ( Ct )
2) Critical pressure ( C p )
The highest temperature at which liquifaction of gases
occurs first is Ct & the pressure required to liquify a
gas at its critical temperature is its Cp.

32. THANKYOU