10 Differences Between ideal gas and real gas

Ideal Gas vs Real Gas

An ideal gas is a theoretical gas composed of randomly moving particles that obey certain idealized gas laws. On the other hand, a real gas is a gas that deviates from ideal behavior and exhibits intermolecular interactions. In this article, we will explore the differences between ideal gas and real gas and discuss their characteristics, examples, and uses.

What is an Ideal Gas?

An ideal gas is a hypothetical gas that strictly follows the ideal gas law and exhibits ideal behavior under all conditions. It is assumed that ideal gases have no volume and do not interact with other gases or their containers. In reality, there are no ideal gases, but this theoretical concept is useful for simplifying calculations and understanding gas laws.

Examples of Ideal Gases

Some commonly used examples of ideal gases include:

  • Helium (He)
  • Hydrogen (H2)
  • Oxygen (O2)
  • Nitrogen (N2)

Uses of Ideal Gases

Ideal gases have several practical applications, such as:

  • Inflating balloons
  • Filling airbags in cars
  • Providing the atmosphere for combustion in gas-powered engines

What is a Real Gas?

A real gas is a gas that deviates from ideal behavior and exhibits intermolecular interactions. Real gases have non-zero volumes and are affected by factors such as pressure, temperature, and molecular attractions. Unlike ideal gases, real gases do not strictly follow the ideal gas law and require more complex equations to accurately describe their behavior.

Examples of Real Gases

Common examples of real gases include:

  • Carbon dioxide (CO2)
  • Methane (CH4)
  • Ammonia (NH3)
  • Water vapor (H2O)

Uses of Real Gases

Real gases find applications in various industries and everyday life:

  • Carbon dioxide is used in fire extinguishers and as a cooling agent.
  • Methane is the main component of natural gas used for cooking, heating, and electricity generation.
  • Ammonia is utilized as a refrigerant and in the production of fertilizers.
  • Water vapor plays a crucial role in the Earth’s climate system and is also used in power plants for energy generation.

Differences between Ideal Gas and Real Gas

Difference Area Ideal Gas Real Gas
Particle Interactions Particles do not interact with each other. Particles exhibit intermolecular attractions and repulsions.
Volume Assumed to have negligible volume. Occupies a finite volume.
Pressure-Volume Relationship Follows the ideal gas law, PV = nRT. Deviates from the ideal gas law due to intermolecular forces.
Temperature-Volume Relationship Volume remains constant with temperature changes. Volume changes with variations in temperature.
Compressibility Perfectly compressible with no resistance. Exhibits resistance to compression due to particle interactions.
Behavior at High Pressures Ideal gas assumptions fail at high pressures. Real gases exhibit significant deviations from ideal behavior at high pressures.
Behavior at Low Temperatures Ideal gas assumptions fail at low temperatures. Real gases undergo liquefaction at low temperatures.
Critical Point Ideal gases do not have a critical point. Real gases have a critical point, beyond which they cannot be liquified by increasing pressure alone.
Equation of State Ideal gas equation is a good approximation under ordinary conditions. Real gases require more complex equations of state to describe their behavior accurately.
Examples Helium, hydrogen, oxygen, nitrogen Carbon dioxide, methane, ammonia, water vapor


In summary, ideal gases are hypothetical gases that follow the ideal gas laws under all conditions, while real gases deviate from ideal behavior due to intermolecular forces and other factors. Ideal gases have no volume and do not interact, whereas real gases have finite volumes and exhibit intermolecular attractions. Understanding the differences between ideal gas and real gas is essential for various scientific and industrial applications.

People Also Ask:

  • What are the assumptions of ideal gas behavior?
  • The assumptions of ideal gas behavior include negligible volume, no intermolecular interactions, and conformity with the ideal gas law under all conditions.

  • Why is it useful to consider ideal gases?
  • Ideal gases provide a simplified model that allows for easier calculations and understanding of gas behavior, particularly under normal conditions.

  • What factors cause a gas to deviate from ideal behavior?
  • Factors such as high pressures, low temperatures, and intermolecular attractions can cause a gas to deviate from ideal behavior.

  • Can a real gas behave like an ideal gas?
  • Under certain conditions, such as low pressures and high temperatures, some real gases can behave similarly to ideal gases. However, no gas behaves perfectly as an ideal gas in all conditions.

  • Why do real gases occupy a finite volume?
  • Real gases have non-zero volumes because the particles themselves possess certain sizes. Additionally, intermolecular forces also contribute to the finite volume of real gases.

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