Question

What is the meaning of two successive collisions?

Answer 1

The study of molecules, by which they form the product and their rate of reaction is determined by various rules is known as Chemical Kinetics. In Kinetics we measure the reaction taking place, the rate of reaction and various theories explaining how a reaction takes place. One of the theories is Collision theory.

Complete answer:
The distance covered by any molecule between two successive collisions is called the free path. This value does not remain constant. Mean free path is the average distance covered by a molecule between any two successive collisions is called the mean free path.
According to Classics, every gas has an infinite number of molecules that are spherical in nature. The size of these molecules is very small as compared to the distance between them. These molecules are in constant motion and move in a zig-zag path. These paths of varying lengths are called free paths of the given molecules and the mean of this path is called the mean free path. We can also define the mean free path as the average distance between the two successive collisions.

Note:
The mean free path can also be defined as the average distance covered by a molecule between two successive collisions. Mathematically, $\lambda = \dfrac{1}{{\sqrt 2 \pi {d^2}\dfrac{N}{V}}}$ . Where $\lambda$ is the average distance traveled by the molecules $d$ is diameter, and $\dfrac{N}{V}$ is a number of moles per given liter of the volume. Rest other terms are constant. It is to remember that the average distance is inversely proportional to the number of moles present.