GASEOUS STATE
Gaseous state is the second physical chemistry topic in the jee
advanced syllabus. It remains an important chapter despite
the lower weightage given to it by iit's.
In this chapter, numericals generally turn out to be easy.
Hence one must focus on the theory and graph analysis.
Some important points:
1. Boyle's law and Charles's law are examples of limiting laws,
a law that is strictly true as pressure tends to 0.
2. An ideal gas is one in which there are no interactions.
3. P = p1 + p2 + p3 +..... ( true for real and ideal gases which
are non reacting and at equilibrium.)
4. However, only in case of an ideal gas, the pressure exerted
on the walls is equal to partial pressure.
Kinetic theory of gases:
1. It is valid when the diameter of molecules is much smaller
than mean free path.
2. Gases are highly compressible.
3. No force of attraction at ordinary temperatures.
4. Collisions are perfectly elastic.
5. Density is constant in all parts of the container.
6. No of collisions per unit volume is constant.
Real Gases:
1. Repulsive interactions occur only when distances are very
small.
2. Attractive forces have a longer range.
3. Van der Waals constants are given symbols " a" and "b".
4. "a" depends on temperature but "b" does not.
5. Real gases behave like ideal gases when temperature is
high and pressure is low.
6. Larger value of "a" implies that the gas occupies lesser
volume due to more attraction.
7. Smaller value of "b" implies greater compressibility.
8. Compressibility Factor - "Z". When Z>1, repulsive
forces dominate. When Z<1, attractive forces dominate.
a useful link for information on real gases
NOTE: Do revise ncert in this chapter and concentrate on
the CO2 isotherm.
Miscellaneous points:
1. Vapour pressure is constant at a given temperature.
2. Joule Thompson effect is not part of the syllabus but those
interested can find the required information in the link
given below.
https://www.comsol.co.in/multiphysics/joule-thomson-effect
THANK YOU
Gaseous state is the second physical chemistry topic in the jee
advanced syllabus. It remains an important chapter despite
the lower weightage given to it by iit's.
In this chapter, numericals generally turn out to be easy.
Hence one must focus on the theory and graph analysis.
Some important points:
1. Boyle's law and Charles's law are examples of limiting laws,
a law that is strictly true as pressure tends to 0.
2. An ideal gas is one in which there are no interactions.
3. P = p1 + p2 + p3 +..... ( true for real and ideal gases which
are non reacting and at equilibrium.)
4. However, only in case of an ideal gas, the pressure exerted
on the walls is equal to partial pressure.
1. It is valid when the diameter of molecules is much smaller
than mean free path.
2. Gases are highly compressible.
3. No force of attraction at ordinary temperatures.
4. Collisions are perfectly elastic.
5. Density is constant in all parts of the container.
6. No of collisions per unit volume is constant.
Real Gases:
1. Repulsive interactions occur only when distances are very
small.
2. Attractive forces have a longer range.
3. Van der Waals constants are given symbols " a" and "b".
4. "a" depends on temperature but "b" does not.
5. Real gases behave like ideal gases when temperature is
high and pressure is low.
6. Larger value of "a" implies that the gas occupies lesser
volume due to more attraction.
7. Smaller value of "b" implies greater compressibility.
8. Compressibility Factor - "Z". When Z>1, repulsive
forces dominate. When Z<1, attractive forces dominate.
a useful link for information on real gases
NOTE: Do revise ncert in this chapter and concentrate on
the CO2 isotherm.
Miscellaneous points:
1. Vapour pressure is constant at a given temperature.
2. Joule Thompson effect is not part of the syllabus but those
interested can find the required information in the link
given below.
https://www.comsol.co.in/multiphysics/joule-thomson-effect
THANK YOU
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