Density of an Ideal Gas – Explanation and Calculation

In thermodynamical and scientific calculations, the ideal gas approach is very important. Because the ideal gas approach makes the calculations much easier. Also, in ideal gas calculations, densities are very important. You need to calculate the densities of ideal gases lots more time. Here, we will show you how to calculate the density of ideal gases simply.

Explanation of equation of state to calculate the density of an ideal gas.

How to Calculate the Density of an Ideal Gas?

Firstly, the density of an ideal gas is very important. And there is one equation you can calculate. We call this equation the equation of state. The equation of state is like this;

You can calculat the density of a ideal gas with this equation.

In this equation, the pressure of an ideal gas is equal to the multiplication of the density, gas constant, and absolute temperature.

The density of the ideal gas has the unit of lb/ft3 which is kg/m3.

R is the gas constant that changes with the type of ideal gas. We calculate the gas constant by dividing the universal gas constant by the molar mass of the gas. So;

Universal gas constant.

In there, Ru is the universal gas constant which is 8.314 kJ/ kmol·K or 1.986 Btu/lbmol·R. The unit of the molar mass is the kg/mole or lbs/mole.

The absolute temperature is Rankine for English units and Kelvinfor SI units.

You can calculate the density of an ideal gas by typing R, T, and P values inside this equation.

Other Form of the Ideal Gas Equation

Also, the other form of the ideal gas equation is like below.

Other form of equation of states

The only change is the density is transformed into the N which is mass/molar mass. And, you can use the universal gas constant directly in this equation.

What is Ideal Gas?

An ideal gas is a very good approximation of real gases at low pressures and high temperatures. With the high temperatures and low pressures, gases are starting to behave like ideal gases. So, an ideal gas approximation can be applied to real gases.

In addition, between the two states of an ideal gas, or real has which is considered an ideal gas, there is a relationship like this;

Ideal gas equation of different states.

This is a very useful relation of ideal gases.


So, the calculation of densities of ideal gases is very simple like above.

Finally, do not forget to leave your comments and questions below about the calculation of the densities of ideal gases.

Your precious feedbacks are very important to us.





Leave a Reply

Your email address will not be published. Required fields are marked *