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The molecular weight of a liquid times the fourth root of its surface tension, divided by the difference between the density of the liquid and the density of the vapor in equilibrium with it; essentially constant over wide ranges of temperature.



the quantity that may reflect certain physical properties of substances, especially nonassociated organic liquids. The parachor was first proposed by the British scientist S. Sugden in 1924. It is calculated according to the formula P = ¼/(ρ1 — ρ2), where M is the molecular mass of the substance, σ is the surface tension, and ρ1 and ρ2 are the densities of the liquid and saturated vapor, respectively.

The parachor is an additive quantity; that is, a compound’s net parachor is the algebraic sum of the parachors of the compound’s constituent parts—individual atoms, atomic groups, or interatomic bonds. The quantities that are associated with the subunits of a compound can be obtained from handbooks. The parachor provides an approximate value for the surface tension of a liquid and is also one of the parameters used to determine the structure of organic compounds.


Bretsznajder, S. Svoistva gazov i zhidkostei. Moscow-Leningrad, 1966. (Translated from Polish.)
Fizicheskie metody organicheskoi khimii, vol. 1. Edited by A. Weissberger. Moscow, 1950. Page 215. (Translated from English.)
References in periodicals archive ?
The surface tension for the poly(amic acid)/THF solution can be calculated from the Parachor relation:
This study also provides a new method to estimate the dynamic interfacial tension and miscibility by incorporating counter-directional diffusivities into the traditional Parachor model.
Cette etude fournit egalement une nouvelle methode pour estimer la tension interfaciale et la miscibilite dynamiques en introduisant des diffusivites contre-directionnelles dans le modele de Parachor traditionnel.
Keywords: interfacial tension, solubility, miscibility, mass transfer, diffusivity, vanishing interfacial tension (VIT) technique, mechanistic Parachor model
Ayirala and Rao (2004a) proposed a diffusivity incorporated mechanistic Parachor model to predict dynamic gas-oil interfacial tension in several crude oil-gas systems.
Our previously developed mechanistic Parachor model (Ayirala and Rao, 2004a) has been utilized to characterize the mass transfer mechanisms from interfacial tension measurements.
The Parachor model (Macleod, 1923; Sudgen, 1924; Weinaug and Katz, 1943) is the oldest among all the IFT prediction models and is still widely used in petroleum industry to estimate the interfacial tension between fluids.
In the Parachor model, Parachor values of pure components were used while calculating the interfacial tensions with an assumption that the Parachor value of a component in a mixture is the same as that when pure.
Next Friday sees him take on Celine Parachor, French world women's conker champion, in a best of three strings match - Ms Parachor will be in the country for the world championships in Northants two days later.
Briggs GG (1981) Theoretical and experimental relationships between soil adsorption, octanol-water partition coefficients, water solubilities, bioconcentration factors, and the parachor.
For example, there are now PC programs available to compute molar refractivity, molar volume, parachor, index of refraction, surface tension, density, dielectric constant, polarizability, dipole moment, acid constant, octanol/water partition coefficient, and other physicochemical properties directly from the SMILES string or molecular structure graph.
The surface tension, and its dispersive and polar contributions, can either be determined experimentally (by contact angle measurements with model liquids) or calculated from group contributions to the parachor (15).