ideal and real gas behaviour

1. PRESENTATION TOPIC: REAL AND IDEAL GAS
BEHAVIOR
GROUP MEMBERS:K15PG03
K15PG50
K15PG79
SUBMITTED TO: SIR ENGR.SHOAIB AHMED MEMON
START WITH THE NAME OF ALLAH WHO IS REHMAN
AND RAHIM

2. REAL AND IDEAL GASES
BEHAVIOR OF GASES

3. GAS
 A gas is a homogeneous fluid, generally of low density
and low viscosity.
Gas has no definite volume but assumed the volume of
any vessel which it is placed.
Specific laws that express the behavior of gases at
various temperature and pressure are very important in
petroleum technology.
The gases are divided into ideal (perfect) gas and real (
non-ideal) gas.

4. KEY CONCEPTS :-
 An Ideal Gas (perfect gas) is one which obeys Boyle's Law and Charles'
Law exactly.
 An Ideal Gas obeys the Ideal Gas Law (General gas equation):
PV = nRT
The properties of hydrocarbon gases are relatively simple since
the parameters of pressure, Volume and temperature (PVT) can
be related by a single equation.

5.  where
P = pressure
V = volume
n = moles of gas
T = temperature
R = gas cons.(dependent on the units of press., temp., and vol.)
R = 8.314 J K-1 mol-1 if
Pressure is in kilopascals(kPa)
Volume is in litres(L)
Temperature is in kelvin(K)
R = 0.0821 L atm K-1 mol-1 if
Pressure is in atmospheres(atm)
Volume is in litres(L)
Temperature is in kelvin(K)

6. Kinetic-Molecular Theory
This is a model that aids
in our understanding of
what happens to gas
particle environmental
conditions change.

7. Main Tenets of Kinetic-Molecular Theory
Gases consist of large numbers of molecules that are in
continuous, random motion.
 The combined volume of all the molecules of the gas is
negligible relative to the total volume in which the gas
is contained.
 Attractive and repulsive forces between gas molecules
are negligible.

8. Main Tenets of Kinetic-Molecular
Theory
 Energy can be transferred
between molecules during
collisions, but the average
kinetic energy of the molecules
does not change with time, as
long as the temperature of the
gas remains constant.
 The average kinetic energy of
the molecules is proportional to
the absolute temperature

9. Real Gases
In the real world, the behavior of gases only
conforms to the ideal-gas equation at relatively high
temperature and low pressure.

10. Deviations from Ideal Behavior
The assumptions made in the kinetic-molecular
model break down at high pressure.

11. K-15PG 50

12. Key Concepts
 Real Gases deviate from Ideal Gas Behaviour because:
 at low temperatures the gas molecules have less kinetic energy
(move around less) so they do attract each other
 at high pressures the gas molecules are forced closer together so
that the volume of the gas molecules becomes significant
compared to the volume the gas occupies

13. Key Concepts
 Under ordinary conditions, deviations from Ideal Gas behaviour are so
slight that they can be neglected
 A gas which deviates from Ideal Gas behaviour is called a non-ideal
gas.

14. GASES LAW (Boyle’s Law)
The volume of a fixed quantity of gas at
constant temperature is inversely proportional
to the pressure.

15. Charles’s Law
 The volume of a fixed amount of gas at constant
pressure is directly proportional to its absolute
temperature.
A plot of V versus T will be a straight line.
• i.e.,
V
T
= k

16. Avogadro’s Law
 The volume of a gas at constant temperature
and pressure is directly proportional to the
number of moles of the gas.
• Mathematically, this means V = kn

17. Standard condition of temperature and pressure is known as STP.
Two things you should know about this is listed below.
 The universal value of STP is 1atm (pressure) and 0° C degree.
Note that this form specifically stated 0° C degree, not 273
Kelvin, even thought you will have to convert into Kelvin when
plugging this value into the Ideal Gas equation or any of the
simple gas equations.
 In STP, 1 mole of gas will take up 22.4 L of the volume of the
container.
17
Standard Temperature and Pressure
(STP)

18. K-15PG 79

19. Ideal-Gas Equation
V  1/P (Boyle’s law)
V  T (Charles’s law)
V  n (Avogadro’s law)
• So far we’ve seen that
• Combining these, we get
V 
nT
P

20. Ideal-Gas Equation
The constant of
proportionality is
known as R, the gas
constant.

21. Ideal-Gas Equation
The relationship
then becomes
nT
P
V 
nT
P
V = R
or
PV = nRT

22. Ideal Gas
 An ideal gas is a theoretical gas or imaginary gas
composed of a set of randomly moving, non-interacting
point like particles and they obeys the gas law always.
An ideal gas is an imaginary gas that obeys gas law under all
conditions

23. Properties of ideal gas
 The gas particles are so small (Point mass) or nearly zero mass or
virtually no volume
 The collision between ideal gases are elastic. i.e. no attractive or
repulsive force during collision

24. Ideal Gas Equation of state
 The functional relationship between P, V & T
𝒇 𝒑, 𝒗, 𝒕 = 𝟎
 Atvery low pressure and high temperature, all real
gases and vapour approaches ideal gas behavior is
called perfect gas.
Real
gas
Perfect
gas
Ideal
gas