Brownian Motion of Molecule

Brownian motion of molecule

As we have studied that all molecules of a gas move randomly in different direction with different velocity and collide with each other elastically.

And temperature of gas defines the average kinetic energy of gas.

Now let’s assume 4 particles in a container having different kinetic energy of same gas.

KE₁>KE₂>KE₃>KE₄

Let’s take 2 group of two –two molecule

Group 1 KE₁, KE₂

Group 2 KE₃ , KE₄

The average kinetic energy of group 1 is higher than group 2 so by definition, temperature of group 1 is higher than group 2.

When molecule 1 collides with molecule 3 and molecule 2 will collides with molecule 4 and according to the assumption of elastic collision, the molecule will change their kinetic energy and by the definition of temperature, the temp of group will get exchanged.

In thermodynamics, if 2 things have different temperature and if they come in contact the heat transfer will occur until the thermal equilibrium i.e. they attain common temperature.

The above two statements contradicts.