Properties of Gases

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Properties of gases
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Properties of Gases Properties of Gases
No definite shape or volume. Gases do not have any definite shape or volume. They occupy all the available space, i.e. the shape and volume of the container in which they are filled.
Gases are compressible. The high volume of a gas can be easily compressed by increasing the pressure upon it.
Gases can be expanded. When temperature is increased, the particles of a gas gain energy. The kinetic energy of gas increases. As a result, the intermolecular attraction decreases and the inter-molecular space increases. Hence, the volume of a gas increases.
Gases exert pressure in all the directions. The pressure of the gas is the force exerted by the gas molecules per unit area on the walls of the container. Barometer or mercury manometers are used to determine the atmospheric pressure or pressure of a gas.
Gases have low densities. Gases have large inter-molecular spaces. The number of molecules per unit volume in a gas is very small as compared to solids and liquids. Hence, they have low densities. The SI unit of density is kg m-3.
Gases diffuse readily. A large amount of intermolecular space exists among gas molecules. When two gases are mixed, particles of one gas can easily pass through the inter-molecular space of the other gas. As a result, both the gases get completely mixed forming a homogeneous mixture. This process of gradual mixing of two substances kept in contact is called diffusion. The unit of diffusion of gas may be cm3 s-1 or dm3 s-1.
Gases can be liquefied. On decreasing the temperature, the kinetic energy of the molecules of a gas is decreased, and on applying the pressure on a cooled gas, the molecules come closer. Hence, the inter-molecular space gets reduced and there is an increase in the number of molecules per unit volume. Thus, gas liquefies.