Acentric factor

The acentric factor ω {displaystyle 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 (or critical compressibility). The acentric factor is said to be a measure of the non-sphericity (centricity) of molecules. As it increases, the vapor curve is 'pulled' down, resulting in higher boiling points.