Pseudorandom ensemble

Template:Multiple issues The acentric factor $\omega$ is a conceptual number introduced by Kenneth Pitzer in 1955, proven to be very useful in the description of matter. It has become a standard for the phase characterization of single & pure components. The other state description parameters are molecular weight, critical temperature, critical pressure, and critical volume.The acentric factor is said to be a measure of the non-sphericity (centricity) of molecules.

It is defined as:

$\omega =-{\log }_{10}(p_r^{\mathrm{s}\mathrm{a}\mathrm{t}})-1,\mathrm{a}\mathrm{t}{T}_r=0.7$.

where $T_r=\frac{T}{T_c}$ is the reduced temperature, $p_r^{\mathrm{s}\mathrm{a}\mathrm{t}}=\frac{p^{\mathrm{s}\mathrm{a}\mathrm{t}}}{p_c}$ is the reduced pressure saturation of vapors.

For many monatomic fluids

$p_r^{\mathrm{s}\mathrm{a}\mathrm{t}}\mathrm{a}\mathrm{t}{T}_r=0.7$,

is close to 0.1, therefore $\omega \to 0$. In many cases, $T_r=0.7$ lies above the boiling temperature of gases at atmosphere pressure.

Values of $\omega$ can be determined for any fluid from $\{T_r,p_r\}$, and a vapor measurement from $T_r=0.7$, and for many liquid state matter is tabulated into many thermodynamical tables.

The definition of $\omega$ gives zero-value for the noble gases argon, krypton, and xenon. $\omega$ is almost exactly zero for other spherical molecules. Experimental data yields compressibility factors for all fluids that are correlated by the same curves when $Z$ (compressibility factor) is represented as a function of $T_r$ and $p_r$. This is the basis premises of three-parameter theorem of corresponding states:

All fluids at any $\omega$-value, in $\{T_r,p_r\}=const.$ conditions, have about the same $Z$-value, and same degree of convergence.Potter or Ceramic Artist Truman Bedell from Rexton, has interests which include ceramics, best property developers in singapore developers in singapore and scrabble. Was especially enthused after visiting Alejandro de Humboldt National Park.

Values of some common gases

Molecule	Acentric Factor
Acetylene	0.187
Ammonia	0.252
Argon	0.000
Carbon Dioxide	0.228
Decane	0.484
Helium	-0.390
Hydrogen	-0.220
Krypton	0.000
Neon	0.000
Nitrogen	0.040
Nitrous Oxide	0.142
Oxygen	0.022
Xenon	0.000

See also

• Equation of state
• Reduced pressure
• Reduced temperature