Suppose that a Brownian particle of mass M is surrounded by lighter particles of mass m which are traveling at a speed u. Then, reasons Smoluchowski, in any collision between a surrounding and Brownian particles, the velocity transmitted to the latter will be mu/M. This ratio is of the order of 10−7 cm/s.

While orbital repulsion is primarily responsible for Brownian motion in fluid, it may contribute the vibrations of particles in the lattice of solid. This force increases with temperature.

Temperature is a measure of the average kinetic energy of the particles in an object. When temperature increases, the motion of these particles also increases. The temperature is related to the average kinetic energy—not the total kinetic energy. Here’s a classic example that you can try at home.

Brownian Motion Examples The motion of pollen grains on still water. Movement of dust motes in a room (although largely affected by air currents) Diffusion of pollutants in the air. Diffusion of calcium through bones. Movement of “holes” of electrical charge in semiconductors.

The phenomenon by which the colloidal particles are in continuous motion is called BROWNIAN MOVEMENT. BROWNIAN movement was named after Robert brown a biologist. He observed the motion of the particles in suspension of pollen grain s in water.

What causes Brownian motion in colloids? Caused by collisions of the molecules of the dispersion medium with the small, dispersed colloidal particles.

The kinetic particle theory explains the properties of solids, liquids and gases. There are energy changes when changes in state occur. Brownian motion is the random movement of fluid particles.

The molecules of gas have more kinetic energy than liquid molecules and are smaller. The distance between the constituent particles in gases becomes greater than in liquids, resulting in diffusion faster in gases than in liquids. Therefore, gas particles have higher kinetic energy and travel more rapidly.

The rate of diffusion increases with the increase of temperature because the kinetic energy of particles increases due to a rise in temperature. Hence particles move and spread out faster. Therefore, on heating diffusion becomes faster.

gases

solid