Question

Name two processes which provide the best evidence for the motion of particles in matter.

Answer 1

We are aware of the fact that matter is not the smallest known particle to exist. We know that matter is composed of further sub atomic particles that are protons, neutrons and electrons. According to the kinetic theory of gases these particles are in continuous movement.

Complete step by step answer:
Though the particles in the matter are continuously in motion. Their motion depends upon the temperature and the state the particles are present in. As we know that on increasing the temperature the motion of particles becomes faster which happens due to the particles attaining kinetic energy and hence it increases their velocity. Also we know that the movement of particles and molecules in gaseous state is more free than the particles in solid and liquid state.
The two of the processes which explain the above are Brownian motion and diffusion. Let us describe each one of them one by one
1. Brownian movement: When the colloidal solutions are viewed under a powerful ultramicroscope, the colloidal particles appear to be in a state of continuous zig-zag motion all over the field of view. This motion was first observed by the British botanist Robert Brown, and is known as Brownian movement. The motion is independent of the nature of the particle but depends upon the size of the particles and the viscosity. Smaller the size lesser the viscosity faster is the motion.
2. Diffusion: It is the process of movement of particles from a region of high concentration to the region of lower concentration, hence diffusion is the net movement that depends upon the gradient in concentration. It is a random movement. Osmosis is a specific type of diffusion that occurs across a membrane that is semi-permeable in nature.

Note:
Brownian motion has been explained due to the unbalanced bombardment of the particles by the molecules of the dispersion medium. It is also responsible for stability of sols.