[Gasification] Gas "Laws"

[Peter Singfield]

Ideal gas law

http://en.wikipedia.org/wiki/Ideal_gas_law

The ideal gas law is the equation of state of a hypothetical ideal gas,
first stated by Benoît Paul Émile Clapeyron in 1834.

The state of an amount of gas is determined by its pressure, volume, and
temperature according to the equation: 

pV=nRT
 
where

p is the absolute pressure [Pa], 
V is the volume [m3] of the vessel containing  moles of gas, 
n is the amount of substance of gas [mol], 
R is the gas constant [8.314?472 m3·Pa·K-1·mol-1], 
T is the temperature in kelvin [K]. 

The ideal gas constant (R) depends on the units used in the formula. The
value given above, 8.314472, is for the SI units of pascal cubic meters per
mole per kelvin, which is equal to joule per mole per degree kelvin (J
mol-1 K-1). Another value for R is 0.082057 L·atm·mol-1·K-1)

The ideal gas law is the most accurate for monoatomic gases at high
temperatures and low pressures. This follows because the law neglects the
size of the gas molecules and the intermolecular attractions. Obviously the
neglect of molecular size becomes less important for larger volumes, i.e.,
for lower pressures. The relative importance of intermolecular attractions
diminishes with increasing thermal kinetic energy 3kT/2, i.e., with
increasing temperatures. The more accurate Van der Waals equation takes
into consideration molecular size and attraction. The ideal gas law
mathematically follows from statistical mechanics of primitive identical
particles (point particles without internal structure) which do not
interact, but exchange momentum (and hence kinetic energy) in elastic
collisions.


Also --

http://en.wikipedia.org/wiki/Combined_gas_law

The combined gas law is a gas law which combines Charles's law, Boyle's
law, and Gay-Lussac's law. In each of these laws pressure, temperature, and
volume must remain constant for the law to be true. In the combined gas
law, any of these properties can be found mathematically.

The law states that:

The product of the volume of a gas and its pressure over the temperature is
equal to a constant. 
Expressed mathematically the formula is:

PV=nRT 
where:

P is the pressure. 
V is the volume. 
n is number of moles. 
T is the temperature (measured in kelvin in SI units). 
r is a constant.(either 0.0821, when dealing with atm's or 8.213 when
dealing with mmHg)