Conditions when real gases behave as ideal gases

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SUMMARY

Real gases behave as ideal gases primarily under conditions of low pressure and high temperature. At low pressure, the intermolecular distances increase, leading to negligible intermolecular forces, while high temperatures enhance molecular motion, further reducing the impact of these forces. Conversely, high pressure results in significant repulsive forces due to close molecular proximity, and low temperatures decrease molecular motion, preventing ideal gas behavior. The kinetic theory assumptions, including negligible molecular size and elastic collisions, support these conclusions.

PREREQUISITES
  • Understanding of kinetic theory of gases
  • Familiarity with gas laws and equations
  • Knowledge of intermolecular forces
  • Basic concepts of thermodynamics
NEXT STEPS
  • Research the Van der Waals equation and its implications for real gases
  • Study the impact of temperature and pressure on gas behavior
  • Explore the concept of intermolecular forces in detail
  • Learn about the conditions under which gases deviate from ideal behavior
USEFUL FOR

Students of chemistry and physics, researchers in thermodynamics, and anyone interested in the behavior of gases under varying conditions.

jd12345
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Well i know real gases behave as ideal gas (almost) when pressure is low and temperature is high. I want to understand this - When pressure is low attractive forces in the gas moelcules will be stronger(as compared to high pressure) but the fast movement due to high temperature compensates it? Am i right?

Why can't it be high pressure and low temperature? Because of high pressure repulsive forces dominate ( because molecules will be very close) but then you lower the temperature and moelcules don't move very fast and that compensates for the repulsive forces

Anything wrong in my reasoning. Please help!
 
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Do you remember assumptions used in the kinetic theory?
 
Yes - molecules have negligible size
no intermolecular forces
elastic collisions
 
No intermolecular forces or negligible intermolecular forces (apart from collisions).

Start from there. What can you say about intermolecular distances in the gas that has a low pressure and a high temp?
 
well in case of low pressure and high temperature - there will be large intermolecular distances so negligible intermolecular forces. So it well behave as an ideal gas. I understand now - thank youAnd if there is high pressure there will be repulsive forces and small distances which does not match with the postulates. Thank you again

But one more question - not closely related to my previous question
In the real gas equation pressure is P + an2/V2. Is the correction term only for attractive forces , only for repulsive forces or both? If its for both does that mean value of "a" changes according to conditions
 

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