Name: Graham's Diffusion Law
Uploaded: 2019-07-19
Duration: 9 min 43 s
Description: Gases diffuse at a different rate. Watch this video to understand Graham's diffusion law, which deals with the diffusion of gases. Have fun learning!

Question

State Maxwell's law of distribution of molecular velocities and explain its significance. How distribution of molecular velocities is affected by temperature.

Accepted Answer

At a particular temperature, different molecules of a gas possess different speeds. Further, due to continuous collisions among the molecules themselves and against the walls of the container, their speeds keep on changing. Maxwell and Boltzmann, however showed that as a result of collisions, though some molecules are speeded up, some others are slowed down and hence the fractions of molecules possessing particular speeds remain constant at constant temperature. If fractions of molecules possessing particular speeds are plotted against their corresponding speeds at a particular temperature, a curve of the type shown in below figure is obtained. This distribution of speeds is called MaxwellBoltzmann distribution.

From this curve, it may be observed:

Fractions of molecules having too low or too high speeds are very small.

The peak of the curve corresponds to a speed possessed by the maximum fraction or a maximum number of molecules. This speed is called the most probable speed and is represented by $c *$ .

Effect of Temperature on the distribution of molecular velocities :

With a variation of temperature, separate curves are obtained for every temperature. At high temperature there will be a wider distribution of velocities. That is the number of molecules having high speed is increased. The maxima, therefore, shift to the right and becomes flattened. The value of the most probable velocity also increases with an increase in temperature. Thus, the effect of temperature on the distribution of molecular velocities can be well explained by the graph.

State Maxwell's law of distribution of molecular velocities and explain its significance. How distribution of molecular velocities is affected by temperature.

Important Questions on States of Matter : Gases and Liquids

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