Difference Between Ideal Gas And Real Gas

Gases present in the atmosphere not only help us in living but protect us from different harmful radiations coming from the sun. So, it is important to study the different properties of gases, their behavior, and their types. In this article, we will discuss the ideal and real gas, and their differences, examples, and applications in various fields.

Difference Between the Ideal Gas and Real Gas

S.No	Properties	Ideal Gas	Real Gas
1.	Definition	It is defined as a gas that follows all the gas laws and the ideal gas equation: PV=nRT.	It is defined as a gas that does not follow the gas laws and ideal gas equation: PV≠nRT.
2.	Equation	PV=nRT.	nRT = ( P + an2/ V2m ) * ( Vm – b ).
3.	Existence	No, they are hypothetical.	Real, they exist in nature.
4.	Shape & Size of particles	Point mass with no volume and shape	Have mass and occupy some space of volume with a fixed shape
5.	The force of interaction b/w particles	Zero or negligible.	Have a finite value of force (a weak Van der Wall force).
6.	Collision	Elastic in nature, means there is no energy loss before and after the collision	Non-elastic in nature means there is some energy loss during a collision.
7.	Compressibility factor(Z)	Always equals 1 (Z=1) Compressibility factor for Ideal gas	Not equal to unity (Z≠1) Z>1 (+ve deviation) Z<1 (-ve deviation) Compressibility factor for Real gas
8.	Phase transition	It does not show a phase transition	It shows phase transition, like liquefication or condensation.
9.	Heat Capacity	It has a constant heat capacity	It has variable heat capacity, which varies according to temperature.
10.	At high pressure and low temperature	It sustains its properties and follows all the gas laws.	It deviates from the ideal gas law.
11.	Examples	No ideal gas exist in nature but under certain condition, some gases like Helium (He), Nitrogen (N2) behaves as an ideal gas.	Carbon dioxide (CO2), Oxygen (O2), and Hydrogen (H2).
12.	Applications	Used to create simplified weather forecasts, used in equilibrium state calculations, and used to model simple chemical reactions.	Used in breathing, photosynthesis, production of carbonated drinks, and perfumes, Used in weather forecasting, and baking process also.

What is Ideal Gas?

It is defined as the gas which follows all the gas laws (Boyle’s law, Charle’s law, and Avogadro’s law). For an ideal gas, it is assumed that the intermolecular force between the gas particle does not exist, which means the particle is free in the container in which they are kept. But this is not the real case, the force between the gas particle is minimum but not zero, which is why no ideal gas exists in this nature, and as a result, the concept of ideal gas is hypothetical. All the ideal gases follow the ideal gas equation: PV=nRT, where

• P = Pressure of the gas exerted on the walls of the container.
• V = Volume of the gas or volume of the container in which the gas is kept.
• n = Number of moles of the gas present in the container.
• R = It is the universal gas constant, whose value is 8.314 JK^-1mol^-1 or 0.821 atmK^-1mol^-1.
• t = It is the temperature in Kelvin.

This equation gives the relation between four variables which are measurable physical quantities of gas.

What is Real Gas?

It is defined as a gas that does not follow gas laws and has its properties. It exists in nature. All the gases that are present in nature are real gases. In real gases, there exists some force of interaction between the gas particles. All the real gases do not follow the ideal gas equation: PV≠nRT, instead they follow the Real gas equation: nRT = ( P + an²/ V²_m ) * ( V_m – b ), in which both a and are known as Van der Waal’s Constant.

But under certain conditions, real gases often behave like ideal gases. Like, under low pressure and high temperature, the gas particles get apart from each other and the force of interaction between them is negligible. Example: Idealised Helium (He) behaves like ideal gas under these conditions.

Conclusion

In conclusion, we can say that it is important to study the difference between ideal gas and real gas, it helps us in understanding the different behavior of gases under different conditions of pressure and temperature. Ideal gas, which follows gas laws and behaves according to it. On the other hand real gas, does not follow any gas laws and assumptions. It is also interesting to note, how a real gas deviates from its nature and follows ideal characteristics. It is also important for scientists and engineers to study, develop and analyze the properties of gases to invent something for a noble cause.

FAQs on Difference Between Ideal Gas And Real Gas

1. Why ideal gas does not exist in nature?

Answer:

It is because of the assumption of the properties of an ideal gas, which believes that the size of the gas particles is point masses and the interaction between them is zero. But in reality, the size of particles is small but not negligible and there exists some force of interaction between the gas particles.

2. Why do real gases only deviate in low pressure, but not in high pressure?

Answer:

Because at high pressure, the volume of gas get decreases and the intermolecular distance between particles decreases, and as a result of this intermolecular interaction increases between the gas particles, and it no longer behaves as an ideal gas.

3. What is the formula for the compressibility factor?

Answer:

The formula for the compressibility factor is: Z = PV/nRT.

4. How to obtain a real gas equation from the ideal gas equation?

Answer:

To obtain a real gas equation from an ideal gas, some corrections are made in the equations:

P_ideal = P_real + an²/v² ——- (i)

V_ideal = V_real – nb ——–(ii), put both the equation in the ideal gas equation PV = nRT to get a real gas equation.

5. Why does the ideal gas equation known as the equation of state?

Answer:

It is because it gives the relationship and values of four variables: Pressure(P), Volume(V), Number of moles(n), and Temperature(T), which are required to find the state of any gas.