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As we know, there are three states of matter or matter states: solid states, liquid states and gaseous states. Pressure, volume, temperature, amount of substance, specific heat, etc are some of the measurable properties of gas.Gaseous State is the simplest state of matter. The state of matter is distinguished from the solid and liquid states by: Relatively low density and viscosity; Relatively great expansion and contraction change in pressure and temperature; The ability to diffuse readily; and the spontaneous tendency to become distributed uniformly throughout any container. The gaseous state of matter occurs between the liquid and plasma states,the latter of which provides the upper temperature boundary for gases.
We are going to briefly talk about the properties of gases and their measurement factors.
The Characteristic properties of gases
The Characteristic properties of the gases are given below:
- No definite shape and volume.
- Expansibility: Gases have boundless expansibility. They extend to fill the whole
Vessels are set in.
- Compressibility: Gases are effortlessly compacted by utilisation of pressure.
- Diffusibility: Gases can diffuse quickly through one another.
- Gases possess the property of diffusion which is independent of the forces of gravitation. Due to the presence of this property, gases can easily mix with each other and remain almost uniformly distributed in the atmosphere.
Measurable Properties of gases
Measurement of mass
The mass or amount of gas can be measured by weighing. Firstly the container in which the gas is enclosed is first weighed. Again according to the definition of matter, we have to measure the mass or amount of the container after removing all the gas present in it. The specification of gaseous state is that mass of gas is the difference of weight of two gases.
That is,
Mass of gas=(weight of container containing the gas)-(weight of container after removing all the gas)
Unit of mass: In SI units,mass is generally expressed in kilograms.
The mass of gas is commonly expressed in terms of numbers of moles(n). The mass is related to the numbers of moles as
No. of moles (n) =mass of substance (gas)/Molar mass .
The value of 1 mole is equal to 6.022 x 1023.
Measurement of Volume
The gas occupies the entire space of the container available to it, the volume of gas is the same as the volume of the container. Therefore, the measurement of the volume gas only requires the measurement of the volume of the container enclosing it.
Unit of Volume: The volume is expressed in units of litres (L). The SI unit of volume is measured in cubic metre (m3).
Measurement of Pressure
Pressure is force per unit area. The measurement of the atmospheric pressure is done with the help of an instrument called the Barometer. Gases exerts uniform pressure in all the directions on the walls of the containers in which they are confined. Thus,the pressure of the gas is the force exerted by the gas per unit area of the walls of the container.
Atmospheric Pressure
The pressure exerted by the gases of all the atmosphere on the surface of the earth is called atmospheric pressure.
Unit of atmospheric pressure
The maximum height of the mercury which can be supported by the atmospheric pressure provides a measure of pressure.
A standard pressure of one atmospheric (1 atm)is defined as the pressure that will support a column of mercury of 76cm height at 00C.
1 atm = 76.0cm of mercury(cm Hg)
1bar =0.987atm.
Measurement of Temperature
Temperature is a measure of hotness or coldness of a body.The hot body is said to be at a higher temperature and the cold body is said to be at lower temperature.
The devices used to measure the temperature are the thermometers. The s most commonly used substance in the thermometers is mercury.
Unit of Temperature:SI unit of Temperature is degree Kelvin(K) and the scale is known as Kelvin scale. The zero point on the Kelvin scale is known as absolute temperature.
Conclusion
Gas molecules have extremely high velocity due to which collisions occur and due to these collisions velocity of gas molecules changes in a very short period.At unchanged conditions, a gas follows an Ideal behaviour but as the conditions start changing, gases deviate from their due behaviour. There are two opposite molecular forces, the forces of attraction and the disruptive forces operating between molecules. When gases do not have any kinetic energy at that time they behave like an Ideal gas as conditions start changing they start gaining kinetic energy and start deviating from their ideal gas behaviour.
At last we conclude that gases are very useful as well as harmful for humans, animals and also for nature.
