Gaseous State

Gaseous state is another state of matter having no fixed shape or volume. The particles move randomly with very high speed and collide among each other or with the walls of the container. This leads to their diffusion or spreading out until they are evenly distributed throughout the container.

  Gasses usually have relatively lower density and viscosity and more contraction and expansion with change in pressure and volume, than in solids and liquids. They have a tendency to diffuse readily and hence get distributed easily throughout the container.

There are three states of matter: solid; liquid and gas. They have different properties, which can be explained by looking at the arrangement of their particles. 

 Gaseous phase is one of the three structural phases. In this phase, thermal mobility of molecules or atoms is strong enough to permit their free motion.

 Measurement of Gas

A gaseous state is where any change in temperature results in evident changes in other quantities like volume and pressure. As the gas fills the whole vessel in which it is put, the importance of the gas equals the magnitude of its container, which in turn is calculated from the dimensions of the container.  

Gases have high kinetic energy as they have massive space between them; the particles move quite swiftly and collide. 

 Characteristics Of Gas

 Gases have high compressibility: The molecules are loosely packed and scattered at longer distances, so these have high compressibility.

• Gases have a lower density than liquids and solids: They pose very low viscosity since the molecules have lower intermolecular forces.

• Gaseous have no shape and volume: Gaseous have no fixed structure, as they have no fixed volume and shape.

• Gaseous mix evenly: The gaseous elements are susceptible to reactions since they have a huge gap between the molecules with which molecules get mixed. 

• Gases are diffusive: Due to the gap between the gaseous molecules, they can combine easily and quickly, called diffusion. 

  Uses of Gas

There are the following uses of gas apart from only breathing:

1. The gas is used for cooking, welding, heating, cooling, etc., in residential & industrial segments.

2. The gas is used for generating electricity and could also act as a renewable power generation plant in case of lack of wind & sun energy.

3. There are many industrial gas uses, such as textiles, plastics, polymers, paper, paints, dyes production, and nickel and aluminium smelters.

4. The gas is used in cosmetics, fertilisers, and medicines. 

5. There are many other gaseous forms, such as LPG, IGL, Fuels, etc., that are used in our day-to-day life. 

 Properties of gasses:

1. Compressibility: Gasses have the highest compressibility among all states of matter.

2. Expandability: Gasses take up the volume of the container and hence, can expand the most out of all other states of matter.

3. Volume of Gases: The molecules of solids and liquids are much tightly packed than that of gasses, hence they acquire lesser volume than gasses do.

4. Pressure: The pressure of the gas becomes larger as more gas is added to the container. Pressure is directly proportional to ‘n’. Also,

              Pressure = Force

                                 Area

          Gasses exert equal pressure in all         

           directions.

5. Density: Gasses have lower density than that of solids and liquids.

6. Diffusion : Gasses intermix easily in all proportions without providing any mechanical aid.

Specifications of Gaseous State: 

1. Gasses are compressible because there is enough intermolecular space. They also collide among themselves and with the walls of the container to produce a gas pressure.

2. The volume of the gas varies inversely with the pressure which concludes that the pressure decreases on increasing the volume. This relationship is given by Boyle’s Law : P1V1 = P2V2 where the number of gas moles and the temperature remain constant.

3. The volume of the gas is directly proportional to the absolute temperature which concludes that the higher is the temperature, more will be the volume. This relationship is given by Charles’s Law:  V1T2 = V2T1 where the number of gas moles and the pressure remain constant.

4. The volume of the gas is directly proportional to the number of gas moles which concludes that more the number of moles, larger will be the volume. This relationship is known as Avagadro’s Law : V1N2 = V2N1 where the temperature and pressure of the gas remain constant.

5. All these law when compiled into a single proportionality form:

             P ∝ [RT/V]

            To change the proportionality into

            equality, we multiply ‘n’ which refer to 

            number of Gas moles.

            The final equation is :

         PV = nRT

        This equation is called the Gas Law

             Equation.

Dalton’s Law of Partial Pressures:

 This law states that the total pressure of mixture of non-reactive gases keeping the temperature and pressure constant, is equal to 

the individual pressures of all gasses. 

ptotal  = p1 +p2+p3+p4…

 P1 = x1 Ptotal

 P2 = x2 Ptotal

 P3 = x3 Ptotal 

 Kinetic molecular theory of gasses:

• Gasses are made of a largeThe Kinetic Equation

• The number of identical particles (atoms or molecules), which are very small and perfectly hard spheres.

• The actual volume of the molecules is negligible as compared to the space between them and hence they are considered as the point  masses.

 Interaction between the particles is negligible.

 Particles of a gas are always in constant and random motion and the collision between them is perfectly elastic.

 The average kinetic energy of the particles of a gas is directly proportional to the absolute temperature.

 Pressure of the gas is due to the collision between gas molecules and walls of the container.  

 Average velocity : √8RT

                                √πM

 Root mean square velocity : √3RT

                                                   √M

 Most probable velocity : √2RT

                                            √M

 Ratio of all three velocity :  1 : 1.128 : 1.224