Difference Between Ideal Gas and Real Gas

Before we dive into the complex topics surrounding the topic of an ideal gas and real gas, let’s discuss their definitions first. As we already know, everything in nature is composed of matter. Matter can exist in four different states – They are solid, liquid, gas and plasma. In solids, the particles are tightly packed with each other. They have strong intermolecular forces of attraction, and they can not take a different shape from their designated one. Liquids have more freedom than solids, with fewer forces between their particles. They can take the shape and size of the container they are put in. Gases, however, have the most freedom with no designated shape or size and negligible forces of attraction. They can move about freely in space. Plasma is any assembly of charged particles, like the material inside a tube light or neon sign.

There are two types of gases: real gas and ideal gas. Ideal gas, as the name suggests, adheres to the Ideal Gas Law. This gas has negligible intermolecular forces. It also does not have a specified volume as such. Real gas is the exact opposite of ideal gas. The molecules present in real gas occupy space. They have intermolecular forces of attraction and even volume.

What is an ideal gas?

The ideal gas is assumed to lack any intermolecular forces of attraction. It is also assumed to have no volume of its own and can expand infinitely to fill up any volume or be compressed infinitely into any volume. Let’s assume that spherical balls are present closely with each other. However, they do not have any contact with each other. They may collide with each other but bear no contact still. The particles of the ideal gas have the liberty to move freely. They are elastic and do not accept any limitations imposed on them by the cruel world. They also don’t have any volume since they are assumed to be perfect points.

Further, the Ideal Gas Law also states that any change that takes place in the overall temperature of the gas also causes a change in the internal temperature of the ideal gas. This, in turn, causes a change in the kinetic energy and is followed by a change in temperature.

An ideal gas depends on:

P: Absolutely Pressure

T: Absolute Temperature

V: Volume

The relationship between them looks like:

Ideal Gas Law: PV = nRT = NkT

Herein, R = Universal Gas Constant = 8.3145 J/mol K

• n = number of moles

• k = Boltzmann Constant 1.38066 x 10^-23 J/K = 8.617385 x 10^-5 eV/K

• k = R/NA
• NA = Avagadro’s Number = 6.0221 x 10²³ /mol

•  N = number of molecules

What is real gas?

Now that we have discussed the definition of an ideal gas, let’s move on to the definition of an ideal gas and real gas. As opposed to an ideal gas, real gas does not adhere to any of the gas laws. It has no relation to the Ideal Gas Law. Unlike ideal gas, real gas has both mass and volume. Real gas has mass, velocity, and even volume. Equations for the ideal gas only approximate the behaviour followed by a real gas.

In certain circumstances, it is noticed that real gases can be more compressible than the ideal gas. However, this can take place only when the pressure value is high. The other factors that it is dependent on are temperature and pressure.

Under room temperature, the pressure and temperature of a few real gases will match those of ideal gases. This can happen if the chemical formula of the gas is simple. Further, the relativity is low as well. For instance, helium.

One more notable point about real gases is: that they liquefy when they are cooled to their boiling points. This helps us understand the definition of an ideal gas and real gas.

The examples of an ideal gas and real gas can be traced as follows: no gas behaves as an ideal gas. However, some real gas examples are ammonia, water vapour, and sulphur dioxide.

Differences between Ideal Gas and Real Gas

The major differences between an ideal gas and real gas are as follows:

Conclusion

In this article, we walked you through the definition of an ideal gas. The ideal gas can be defined as a gas that lacks any intermolecular forces of attraction. It also has no volume of its own. Let’s assume that spherical balls are present closely with each other. However, they do not have any contact with each other. The particles of this ideal can move freely. On the other hand, real gas is the exact opposite of this. The definitions of an ideal gas and real gas are different. A real gas is defined as a gas that does not adhere to any of the gas laws. It has no relation to the Ideal Gas Law. Unlike ideal gas, real gas has both mass and volume. Once it starts gaining mass and volume, it deviates from its ideal behaviour and transforms into the real gas. The differences between an ideal gas and real gas are clear from this as well. We’ve discussed all the major pointers of the same.