Values of Gas Constant and Numerical Expressions

An ideal gas follows gas laws

There are three main gas laws

Boyle’s Law states that volume of a gas is inversely proportional to pressure when temperature and number of moles are constant

Charles's law states that the volume of a gas is directly proportional to temperature when pressure and number of moles are constant

Avogadro’s Law states that a gas contains equal no. of molecules in equal volumes of gases at the constant temperature and pressure

Combining these 3 laws, we get the ideal gas equation

Let's see what happens if we keep the number of moles of gas constant in ideal gas equation

So, let us say that initial conditions are given by , and . So =

Later, the conditions are changed to , and . So =

Equating these two, we get,

This is another form of the ideal gas equation when the number of moles of gas is not changed

We can also find the gas constant R using the combined gas law

Here is the pressure is the volume, is the no. of molecules and is the temperature

Let us take the standard conditions for an ideal gas and find

Substituting these values in the equation for gas constant

can also be found in the units

For this unit of pressure should be changed from bar to Pascals

Unit of volume should be changed from to

By substituting the above values, we get the value of in

The unit is equal to unit of energy . So

can also be found in the units . For this we will have to substitute

So the value of

Revision

A gas that follows the gas rules is an ideal gas

There are three main gas laws - Boyle’s, Charles's and Avogadro’s Laws

Combining the above three laws we get the ideal gas law where

In combined gas law,

The End