text: Correlations using this quantity were extended by Halm and Stiel using a similarly-defined quantity which represents polarity.
full_question: Correlations using this quantity were extended by Halm and Stiel using a similarly-defined quantity which represents polarity. The first Mathias-Copeman constant and the kappa parameter in the PRSV equation are defined as polynomials in terms of this quantity. The saturation vapor pressure and several other parameters can be modeled as linear functions of this quantity using the Lee-Kesler method. This quantity is the third parameter in the 3-parameter theorem of corresponding states. The alpha functions which appear in the Soave modification and the Peng-Robinson equation are functions of temperature and this quantity. It is defined as negative 1 minus the log of the reduced pressure evaluated at a reduced temperature of 0.7. Developed by Pitzer, for 10 points, name this quantity which measures deviations from ideal-gas behavior due to the fact that molecules are not spherical.
first_sentence: Correlations using this quantity were extended by Halm and Stiel using a similarly-defined quantity which represents polarity.
raw_answer: acentric factor [or acentricity; prompt on "Pitzer factor"]