Obeying Gas Laws

For example, gases expand to fill the entire volume of any container in which you put them. Also, gases are easily compressed into smaller volumes. Even more so than liquids, gases easily form homogenous mixtures. Because so much open space occurs between individual gas particles, these particles cire pretty laid back about the idiosyncrasies of their neighbors. 

Chapter 10 sets down the basic assumptions of the kinetic molecular theory of gases, a set of ideas that explains gas properties in terms of the motions of gas particles. In summary, kinetic molecular theory describes the properties of ideal gases, ones that conform to the following criteria  

Ideal gas particles have a volume that is insignificant compared to the volume the gas occupies as a whole. The relatively small volume of a 20-ounce soda bottle, for example, completely dwarfs the individual gas particles inside the bottle, making their sizes irrelevant to any ideal gas calculation. 

Ideal gases consist of very large numbers of particles in constant random motion. These particles collide with the walls of their container, and these collisions with the walls cause the pressure exerted by the gas. 

Ideal gas particles are neither attracted to one another nor repelled by one another. 

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It is detemrined experimentally an early study was the work of Andrews on carbon dioxide [1], The exact fonn of the equation of state is unknown for most substances except in rather simple cases, e.g. a ID gas of hard rods. However, the ideal gas law P = pkT, where /r is Boltzmaim s constant, is obeyed even by real fluids at high temperature and low densities, and systematic deviations from this are expressed in tenns of the virial series ... 

The behavior of all gases that obey the laws of Boyle and Charles, and Avogadro s hypothesis, can be expressed by the ideal gas equation ... 

At pressures less than 2 MPa (20 bar) and temperatures greater than 273 K, PC 1.0. When the vapor obeys the ideal gas law, 2 = 1.0 then for ideal vapor solutions and for conditions such that PC = 1.0, equation 19 reduces to equation 6. 

Ideal gas obeys the equation of state PV = MRT or P/p = MRT, where P denotes the pressure, V the volume, p the density, M the mass, T the temperature of the gas, and R the gas constant per unit mass independent of pressure and temperature. In most cases the ideal gas laws are sufficient to describe the flow within 5% of actual conditions. When the perfect gas laws do not apply, the gas compressibility factor Z can be introduced ... 

The Lapple charts for compressible fluid flow are a good example for this operation. Assumptions of the gas obeying the ideal gas law, a horizontal pipe, and constant friction factor over the pipe length were used. Compressible flow analysis is normally used where pressure drop produces a change in density of more than 10%. 

Since non-ideal gases do not obey the ideal gas law (i.e., PV = nRT), corrections for nonideality must be made using an equation of state such as the Van der Waals or Redlich-Kwong equations. This process involves complex analytical expressions. Another method for a nonideal gas situation is the use of the compressibility factor Z, where Z equals PV/nRT. Of the analytical methods available for calculation of Z, the most compact one is obtained from the Redlich-Kwong equation of state. The working equations are listed below ... 

If the reaetant and produet obey tlie ideal gas law, the eoneentration is... 

It has been satisfactorily demonstrated by Henning that the vapours of odoriferous substances obey the general gas laws, and there is consequently no need to assume any additional factor of the nature of specific solubility. 

If each component gas as well as the mixture obeys the ideal gas law, it follows that the pure-component volume of component i is... 

It would appear at first sight necessary to define an ideal gas as one which strictly obeys all the gas laws. As a matter of fact we can prove that if it conforms to two conditions it will conform to all the conditions we shall take as defining an ideal gas. 

Moutier s equation evidently applies to any gas, whether it obeys the laws of ideal gases or not, provided Av is small. 

If we neglect v1 in comparison with vn, and assume the vapour obeys the gas laws, we have, for a mol ... 

Again we assume that F is negligible in comparison with V2, and that the saturated vapour obeys the gas laws.. 

At very low temperatures the pressures of the saturated vapours of liquids and solids are very small, and since the deviation of an actual gas from the laws of ideal gases becomes all the less the smaller is its density ( 70), we can safely assume that the vapour obeys the gas laws. 

Steam is the working fluid in most boiler operations and usually can be treated as an ideal gas that is, a gas that obeys the ideal gas law. This law states that the pressure (P) of a volume of gas (v) is equal to the product of the universal gas constant (R) and temperature (7). 

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