Difference Between Ideal Gas and Real Gas

IDEAL GAS vs REAL GAS

The states of matter are liquid, solid, and gas which can be recognized through their key characteristics. Solids have strong composition of molecular attraction giving them definite shape and mass, liquids take the form of their container since the molecules are moving that corresponds to one another, and gases are diffused on air since the molecules are moving freely. The characteristics of gases are very distinct. There are gases that are strong enough to react with other matter, there are even with very strong odour, and some can be dissolved in water. Here we will be able to note some differences between ideal gas and real gas. The behaviour of real gases is very much complex while the behaviour of ideal gases is much simpler. The behaviour of real gas can be more tangible by understanding fully the behaviour ideal gas.

This ideal gas can be considered as a “point mass”. It simply means that the particle is extremely small where its mass is almost zero. Ideal gas particle, therefore, does not have volume while a real gas particle does have real volume since real gases are made up of molecules or atoms that typically take up some space even though they are extremely small. In ideal gas, the collision or impact between the particles are said to be elastic. In other words, there is neither attractive nor repulsive energy included throughout the collision of particles. Since there is lack of inter-particle energy the kinetic forces will remain unchanged in gas molecules. In contrast, collisions of particles in real gases are said to be non-elastic. Real gases are made up of particles or molecules that may attract one another very strongly with the expenditure of repulsive energy or attractive force, just like water vapor, ammonia, sulfur dioxide, and etc.

The pressure is much greater in ideal gas as compared to the pressure of a real gas since the particles do not have the attractive forces that enable the molecules to hold back when they will collide at an impact. Hence, particles collide with less energy. Differences that are distinct between ideal gases and real gases may be regarded most clearly when the pressure will be high, these gas molecules are large, the temperature is low, and when the gas molecules excerpt strong attractive forces.

PV=nRT is the equation of ideal gas. This equation is important in its ability to connect together all the fundamental properties of gases. T stands for Temperature and should always be measured in Kelvin. “n” stands for the number of moles. V is the volume which is usually measured in liters. P stands for pressure wherein it is usually measured in atmospheres (atm), but can also be measured in pascals. R is considered ideal gas constant which never changes. On the other hand, since all real gases can be converted to liquids, Dutch physicist Johannes van der Waals came up with an modified version of the ideal gas equation (PV = nRT):

(P + a/V2) (V – b) = nRT. The value of “a” is constant as well as “b”, and therefore should be experimentally determined for each gas.

SUMMARY:

1.Ideal gas has no definite volume while real gas has definite volume.

2.Ideal gas has no mass whereas real gas has mass.

3.Collision of ideal gas particles is elastic while non-elastic for real gas.

4.No energy involved during collision of particles in ideal gas. Collision of particles in real gas has attracting energy.

5.Pressure is high in ideal gas compared to real gas.

6.Ideal gas follows the equation PV=nRT. Real gas follows the equation (P + a/V2) (V – b) = nRT.

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